DE102020008034A1 - Method for emitting ultrasonic bursts with decreasing ultrasonic burst spacing with decreasing distance - Google Patents

Abstract

The invention relates to a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles. The method comprises the steps
1. Step 1: Transmission of an ultrasonic burst with an ultrasonic burst duration which does not exceed a maximum ultrasonic burst duration by an ultrasonic sensor system (USS);
2. Step 2: receiving an ultrasonic burst reflected by an object;
3. Step 3: determining the distance between the ultrasonic sensor system and the object as a function of the received reflected ultrasonic burst;
4. Step 4: Repeat steps 1 to 4, the ultrasonic burst duration depending on the distance determined
The method is characterized in that the temporal ultrasonic burst interval of the ultrasonic bursts becomes shorter with decreasing spatial distance between the ultrasonic sensor system and the object.

Description

Field of invention

The invention is directed to an apparatus and a method for transmitting more complex ultrasonic bursts through a space division multiplex of different ultrasonic apparatuses.

General introduction

In the context of autonomous driving, better and better measuring devices are required to clarify the vehicle's surroundings. There are clear limits to the bandwidth of the ultrasonic signals that can be transmitted and received, since the ultrasonic transducers used have a strong resonance of high quality and thus a small bandwidth.

It is therefore necessary to optimize the course of the modulation frequency within a chirp signal.

In this context we refer here to the WO 2010/063 510 A1 there. the WO 2010/063 510 A1 describes a detection device and a method for detecting the surroundings of a vehicle. the WO 2010/063 510 A1 uses signals that are of particular interest in connection with the use of ultrasound in vehicles.

From the EP 1 231 481 A2 discloses a method of operating an ultrasonic multisensor array that does not address the bandwidth problem.

From the US 7 693 007 B2 an ultrasonic sensor with a separate ultrasonic transmitter and ultrasonic receiver is known.

None of the featured fonts solve or contribute to the bandwidth problem.

task

The proposal is therefore based on the object of creating a solution that does not have the above disadvantages of the prior art and has further advantages.

This object is achieved by a proposal according to the claims. Their solution is more precisely supported by the proposal according to the claims. Further refinements are the subject of the subclaims.

Solution of the task

1. 1. Schritt 1: Aussenden eines Ultraschallbursts mit einer Ultraschallburstdauer (bd), die eine maximale Ultraschallburstdauer (bd) nicht überschreitet, durch ein Ultraschallsensorsystem (USS);
2. 2. Schritt 2: Empfangen eines durch ein Objekt (O) reflektierten Ultraschallbursts;
3. 3. Schritt 3: Bestimmen des Abstands (D) zwischen dem Ultraschallsensorsystem (USS) und dem Objekt (O) in Abhängigkeit von dem empfangenen reflektierten Ultraschallburst;
4. 4. Schritt 4: Wiederholen der Schritte 1 bis 4, wobei die Ultraschallburstdauer (bd) von dem ermittelten Abstand (s1, s2) abhängt

The invention relates to a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles. The method comprises the steps

1. 1. Step 1: Sending an ultrasonic burst with an ultrasonic burst duration ( bd ), which have a maximum ultrasonic burst duration ( bd ) is not exceeded by an ultrasonic sensor system ( USS );
2. 2. Step 2: Receiving a by an object ( O ) reflected ultrasonic bursts;
3. 3. Step 3: Determine the distance ( D. ) between the ultrasonic sensor system ( USS ) and the object ( O ) as a function of the received reflected ultrasonic burst;
4. 4. Step 4: Repeat steps 1 to 4, using the ultrasonic burst duration ( bd ) from the determined distance ( s1 , s2 ) depends

The method is characterized in that the temporal ultrasonic burst interval of the ultrasonic bursts with decreasing spatial distance ( D. ) between the ultrasonic sensor system and the object ( O ) becomes shorter in time.

A method of adapting the ultrasonic signals, more precisely the ultrasonic bursts ( UB ) to the object to be examined in the vicinity of a vehicle is the adaptation of the transmission amplitude and the transmission frequency when an object is detected as a function of object properties, such as distance and / or reflectivity. For this purpose, the reception amplitude is measured by an ultrasonic measuring device, the ultrasonic sensor system ( USS ), by means of an appropriate ultrasonic receiver and / or ultrasonic transducer ( US1 , US2 , US3 ) and compared with a target reception amplitude curve. If the reception amplitude is too high at any point in time, the ultrasonic transducers are attenuated individually or together. The damping of one or more ultrasonic transducers is preferably done by connecting damping elements, for example by connecting resistors in parallel to the ultrasonic transducers ( US1 , US2 , US3 ). If the amplitude is too low, the relevant ultrasonic transducer is supplied with more vibration energy.

Another method is to regulate the ultrasonic burst amplitude ( A. ) with which the ultrasonic transducer ( US1 , US2 , IS3) sends. An attempt is made to determine the reception amplitude of the echoes when they are received by the ultrasonic transducer ( US1 , US2 , US3 ) at the location of the relevant ultrasonic transducer or at the location of the ultrasonic sensor system ( USS ), which has multiple ultrasonic transducers ( USS ) includes keeping constant. A central idea of this disclosure is the adaptation of the ultrasonic burst properties to the previously recognized environment. In this case, it is ultimately irrelevant whether the detection was carried out by means of ultrasound or other methods such as radar and / or lidar and / or by means of image evaluation of camera images. Such an adaptation of an ultrasound burst characteristic for ultrasound bursts to be transmitted can be, for example, an increase and / or decrease in the ultrasound burst amplitude when the ultrasound burst is transmitted as a function of the distance from an object to be examined or detected. In an analogous manner, the instantaneous ultrasonic burst frequency when the ultrasonic burst is emitted can also be increased or decreased as a function of the distance from the object.
An essentially hyperbolic curve of the instantaneous ultrasonic burst frequency as a function of the time within an ultrasonic burst is particularly preferred for better Doppler robustness.

For the detection of a small object, for example the size of a moth, at a distance of 15 m, a sound pressure of 130 dB with an ultrasonic burst duration of 10 ms and a time interval of 110 ms between two successive ultrasonic bursts are typically useful. High sound pressure, low frequency, long pulse duration and low pulse repetition frequency are important.

• • exakte 3D-Lokalisierung
• • Strukturerfassung (Objektklassifizierung, Größe, sensitive Objektkomponenten (z.B. bestimmte zu schützende Körperteile eines Menschen))
• • Kompensation des Dopplereffekts

When approaching an object in the vehicle environment that has been identified as important, the tasks arise

• • exact 3D localization
• • Structure detection (object classification, size, sensitive object components (e.g. certain parts of the human body to be protected))
• • Compensation of the Doppler effect

• • Kurz mit hoher Wiederholrate (80 bis 90 Ultraschallbursts /Sekunde bei Annäherung),
• • bis zu 200 Ultraschallbursts /Sekunde in der Nähe des Objekts,
• • Breitbandige Aussendung und Empfang der Ultraschallbursts, um mehr spektrale Information zu erhalten,
• • Lineare oder hyperbolisch abwärts weisende Frequenzmodulation der Ultraschallbursts,
• • Reduktion der Ultraschallburstamplitude in der Nähe des Objekts, was Übersteuerungen verhindert.

Ultrasonic bursts in this phase:

• • Short with high repetition rate (80 to 90 ultrasonic bursts / second when approaching),
• • up to 200 ultrasonic bursts / second near the object,
• • Broadband transmission and reception of the ultrasonic bursts in order to obtain more spectral information,
• • Linear or hyperbolic downward-pointing frequency modulation of the ultrasonic bursts,
• • Reduction of the ultrasonic burst amplitude in the vicinity of the object, which prevents overmodulation.

In the approach phase to the object or to a group of objects, the sequence and shape of the ultrasonic bursts are preferably continuously changed during the approach: At greater distances, the ultrasonic bursts are preferably loud with a large ultrasonic burst amplitude and a relatively low-frequency ultrasonic instantaneous frequency, and preferably narrow band. Frequency-modulated so-called chirps with a higher starting frequency and a quieter, ie smaller, ultrasonic burst amplitude in the vicinity of the object or objects are preferably used. For good processing, very fast signal processing for high pulse repetition frequencies is useful.

A 3D localization option for objects can be obtained by means of several ultrasonic transducers that are suitably placed with respect to one another. If the ultrasound transducers are very broadband, for example 2 sensors can be placed next to each other at “ear distance”. This document proposes increasing the broadband capability by coupling several ultrasonic transducers to form an ultrasonic sensor system. A determination of the direction can take place in particular by means of differences in transit time. Such runtime differences can be evaluated using a neural network. An evaluation of the relationship between the height of the reflecting object and the frequency content of the echo can also take place via a neural network. One proposal, which is further elaborated below, includes two ultrasound transducers that are placed close together. One of these two ultrasound transducers should be provided with a low resonance frequency and the other of the two ultrasound transducers should be provided with a high resonance frequency, which are activated in different distance ranges from the object to transmit the ultrasonic bursts.

1. a. Abstandsfehler: Überschätzung der Entfernung zum Objekt,
2. b. Genauigkeitsfehler: Das Objekt kann nicht mehr so präzise lokalisiert werden (Aufweitung der CCF-Kurve)

A vehicle moving towards an object must compensate for two Doppler errors:

1. a. Distance error: overestimation of the distance to the object,
2. b. Accuracy error: the object can no longer be localized as precisely (expansion of the CCF curve)

1. 1. Beide Fehler werden verringert, wenn bei gleichbleibender Ultraschallburstdauer die Bandbreite erhöht wird, oder bei gleichbleibender Bandbreite, die Ultraschallburstdauer reduziert wird.
2. 2. Da das Fahrzeug sich in der Regel auf das interessierende Objekt zubewegt führt dies zu einer Unterschätzung des Abstands auf Basis von Laufzeitbestimmungen. Dies kann die Überschätzung durch den Dopplereffekt bei einer bestimmten Distanz zum Objekt kompensieren. Der Ultraschallburst wird daher vorschlagsgemäß laufend entsprechend angepasst, damit der kompensierte Abstand dem realen Abstand entspricht. Bevorzugt wird hierfür ein neuronales Netz verwendet. Dieses neuronale Netz regelt bevorzugt auf Basis eines oder mehrerer empfangener Ultraschalsignale oder auf Basis von aus den empfangenen Ultraschallsignalen abgeleiteten Signalen einen oder mehrere Ultraschallburstparameter eines oder mehrerer zeitlich nachfolgender Ultraschallbursts.
3. 3. Eine vollständige Kompensation des Genauigkeitsfehlers erfolgt nur bei einer streng hyperbolischen Frequenzmodulation der Ultraschallburstmomentanfrequenz während des Ultraschallbursts in Abhängigkeit von der Zeit (t).

Compensation is necessary for this:

1. 1. Both errors are reduced if the bandwidth is increased while the ultrasonic burst duration remains the same, or if the ultrasonic burst duration is reduced if the bandwidth remains the same.
2. 2. Since the vehicle is usually moving towards the object of interest, this leads to an underestimation of the distance based on transit time determinations. This can compensate for the overestimation caused by the Doppler effect at a certain distance to the object. The ultrasonic burst is therefore continuously adapted accordingly, as proposed, so that the compensated distance corresponds to the real distance. A neural network is preferably used for this. This neural network regulates one or more ultrasonic burst parameters of one or more temporally subsequent ultrasonic bursts preferably on the basis of one or more received ultrasound signals or on the basis of signals derived from the received ultrasound signals.
3. 3. A complete compensation of the accuracy error occurs only with a strictly hyperbolic frequency modulation of the ultrasonic burst instantaneous frequency during the ultrasonic burst as a function of time ( t ).

In principle, a short ultrasonic burst duration with a high bandwidth is therefore desirable in order to obtain a maximum of information. By training a neural network to adapt the ultrasonic burst properties of the ultrasonic bursts to be transmitted in the future, this neural network can be used to determine and set these ultrasonic burst properties before the transmission of an ultrasonic burst. The goal is the optimal ultrasonic burst adaptation for variable compensating distance.

For structure detection and / or object classification, it makes sense to evaluate the fine structure of the echoes of the ultrasonic bursts. This makes use of the fact that each part of an object, for example a pedestrian, reflects the ultrasonic burst at slightly different times. A “depth profile” of the object can then be created from the resulting fine temporal structure of the echo. At the same time, there are also spectral differences due to the different reflection / absorption behavior of different materials on the different surfaces of the object.

As with 3D localization, differences between the received signals on several ultrasonic sensor systems with several ultrasonic transducers are evaluated. The environment of the ultrasonic sensor system, for example the type of mounting or the structure of the surfaces in the vicinity of the ultrasonic sensor system and other components, preferably add further frequency filtering, the removal of which the neural network that is used for the evaluation must be trained to remove.

The invention relates to a method for transmitting an ultrasonic signal by means of an ultrasonic sensor system ( USS ). The ultrasonic signal has an ultrasonic burst ( UB ), with the ultrasonic burst at least two, but typically considerably more ultrasonic pulses ( P ₀ until P ₇ ) having. Each of the at least two ultrasonic pulses ( P ₀ until P ₇ ) has a temporal ultrasound pulse start and a temporal ultrasound pulse end. For example, the intersection of the burst-like fluctuating sound pressure during the ultrasonic burst with the 50% sound pressure amplitude based on the maximum sound pressure occurring during an ultrasonic pulse can be used to determine the start and end of the ultrasonic pulse. The ultrasonic period ( T ₁ until T ₇ ) of a single ultrasonic pulse ( P ₀ until P ₇ ) in the sense of this document is the time from the temporal end of the ultrasonic pulse of the immediately preceding ultrasonic pulse to the temporal end of the ultrasonic pulse of the relevant ultrasonic pulse. These definitions are chosen to give an ultrasonic instantaneous frequency ( f _m ) to be able to determine in the time of the ultrasonic pulse. In the broadest sense, an ultrasound pulse in the sense of this document is a wavelet, the stretching factor of which can be varied during the duration of the ultrasound pulse. In this respect, therefore, within the meaning of this document, any type of time-limited wavelet with a time-limited wavelet duration is encompassed by the term ultrasonic pulse. The wavelet duration corresponds to the ultrasound pulse duration (ie) the ultrasound period ( T ₁ until T ₇ ). The respective instantaneous ultrasonic frequency (f _m1 to f _m7 ) is the reciprocal of the respective ultrasonic period ( T ₁ until T ₇ ) of the respective ultrasound pulse ( P ₀ until P ₇ ). The rate of change ( v _f ) the ultrasonic instantaneous frequency ( f _m ) is thus the first derivative of the ultrasonic instantaneous frequency ( f _m ) after the time ( t ). The ultrasonic burst ( UB ) starts at the beginning of an ultrasonic burst ( UBS ), which is equal to the start of the ultrasonic pulse of the first pulse ( P ₀ ) of the ultrasonic burst ( UB ) is. The ultrasonic burst ( UB ) ends in an ultrasonic burst end ( UBE ), which is equal to the end of the ultrasonic pulse of the last pulse ( P ₇ ) of the ultrasonic burst ( UB ) is. The ultrasonic burst ( UB ) has a burst duration (BD) which is the value of the time difference between the start of the ultrasonic burst ( UBS ) and the ultrasonic burst end ( UBE ) is. In this disclosure it is now proposed that the ultrasonic burst ( UB ) temporally in a first burst phase ( t _1a ) and a second burst phase ( t _1b ) by a first half-frequency point in time ( t _1/50% ) can be shared. The first half-frequency time is ( t _1/50% ) the point in time within the transmission time of an ultrasonic burst ( UB ), to which the ultrasonic instantaneous frequency ( f _m ) the first upper half-maximum amplitude frequency ( f _1o ) or the first lower half-maximum amplitude frequency ( f _1u ) is equivalent to. At the first top Half-maximum amplitude frequency ( f _1o ) the amplitude is ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ). The first upper half-maximum amplitude frequency ( f _1o ) of the first ultrasonic transducer ( US1 ) is above the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ). At the first lower half-maximum amplitude frequency ( f _1u ) the amplitude is ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) also half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ). The first lower half-maximum amplitude frequency ( f _1u ) of the first ultrasonic transducer ( US1 ) is below the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ).

The invention is characterized in that the amount of the mean rate of change ( v _f ) the ultrasonic instantaneous frequency ( f _m ) in the first burst phase ( t _1a ) on the amount of the mean rate of change ( v _f ) the ultrasonic instantaneous frequency ( f _m ) in the second burst phase ( t _1b ) preferably deviates by more than 10% and / or better by more than 20% and / or better by more than 50% and / or better by more than 100%.

The first burst phase ( t _1a ) has a temporal length that depends on the temporal length of the second burst phase ( t _1b ) deviates by more than 10% and / or by more than 20% by more than 50% by more than 100%.

The length of the first burst phase is also preferred ( t _1a ) by more than 10% and / or by more than 20% by more than 50% by more than 75% shorter than the length of the second burst phase ( t _1b ).

According to the proposal, this method can be _{carried out simultaneously at several instantaneous ultrasonic frequencies (f m1} , f _m2 ), which provides additional information about objects that may be in the vicinity of the vehicle. It is then a process for the transmission of an ultrasonic signal, the ultrasonic signal being a total ultrasonic burst ( UB ) and where the total ultrasonic burst ( UB ) comprises a first partial ultrasound burst and wherein the total ultrasound burst ( UB ) comprises a second partial ultrasound burst. Each partial ultrasonic burst of the partial ultrasonic bursts has at least two, typically significantly more, ultrasonic pulses ( P ₀ until P ₇ ) on. Each of the at least two ultrasonic pulses ( P ₀ until P ₇ ) of an ultrasound partial burst again has a temporal ultrasound pulse start and a temporal ultrasound pulse end. The ultrasonic period ( T ₁ until T ₇ ) of a single ultrasonic pulse ( P ₀ until P ₇ ) of an ultrasound partial burst, hereinafter referred to as the relevant ultrasound pulse, is again the time from the temporal ultrasound pulse end of the ultrasound pulse immediately preceding the relevant ultrasound pulse to the temporal ultrasound pulse end of the relevant ultrasound pulse. The first ultrasonic instantaneous frequency ( f _1m ) of the first ultrasonic partial burst is the reciprocal of the instantaneous ultrasonic period (T 1m) of the first ultrasonic _{partial burst.} The second ultrasonic instantaneous frequency ( f _2m ) of the second ultrasonic partial burst is the reciprocal of the instantaneous ultrasonic period (T 2m) of the second ultrasonic _{partial burst.} The first partial ultrasound burst begins at a first start time ( t _1s ), which is equal to the start of the ultrasound pulse of the first ultrasound pulse ( P ₀ ) of the first partial ultrasound burst. The first partial ultrasound burst ends at a first end time ( t _1e ), which is equal to the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the first partial ultrasonic burst. The first ultrasonic partial burst has a first ultrasonic partial burst duration ( t _1e - t _1s ), which is the value of the time difference between the first end time ( t _1e ) minus the first start time ( t _1s ) is. The second partial ultrasound burst begins at a second start time ( t _2s ), which is equal to the start of the ultrasound pulse of the first ultrasound pulse ( P ₀ ) of the second ultrasonic partial burst. The second partial ultrasound burst ends at a second end time ( t _2e ), which is equal to the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the second partial ultrasonic burst. The second ultrasonic partial burst has a second ultrasonic partial burst duration ( t _2e - t _2s ), which is the value of the time difference between the second end time ( t _2e ) minus the second start time ( t _2s ) is. This method variant is characterized in that the first ultrasonic instantaneous frequency ( f _1m ) from the second instantaneous ultrasonic frequency ( f _2m ) at least one time between the first start time ( t _1s ) and the first end time ( t _1e ) and at the same time between the second start time ( t _2s ) and the second end time ( t _2e ) is different. So there are always two ultrasonic instantaneous frequencies (fm1, fm2) by the ultrasonic sensor system ( USS ) sent out.

A first variant of the method provides that the second start time ( t _2s ) between the first start time ( t _1s ) and the first end time ( t _1e ) and / or that the second start time ( t _2s ) equal to the first start time ( t _1s ) is.

In another variant, the second end time is ( t _2e ) between the first start time ( t _1s ) and the first end time ( t _1e ) and / or the second end time ( t _2e ) is equal to the first end time ( t _1e ).

In some applications it can make sense that the first ultrasonic instantaneous frequency ( f _1m ) at the first end time ( f _1e ) equal to the second instantaneous ultrasonic frequency ( f _2m ) at the second end time ( f _2e ) is.

In other applications it can be useful if the first ultrasonic instantaneous frequency ( f _1m ) at the first start time ( f _1s ) equal to the second instantaneous ultrasonic frequency ( f _2m ) at the second start time ( f _2s ) is.

In yet other applications it can be useful if the first ultrasonic instantaneous frequency ( f _1m ) at the first start time ( f _1s ) different from the second instantaneous ultrasonic frequency ( f _2m ) at the second start time ( f _2s ) is.

And in still other applications it can be useful if the first ultrasonic instantaneous frequency ( f _1m ) at the first end time ( f _1e ) different from the second instantaneous ultrasonic frequency ( f _2m ) at the second end time ( f _2e ) is.

1. a. des Erzeugens des ersten Ultraschallteilbursts mit einem ersten Ultraschall-Transducer (UBS1) und/oder
2. b. des Erzeugens des zweiten Ultraschallteilbursts mit einem zweiten Ultraschall-Transducer (UBS2), der vom ersten Ultraschall-Transducer (UBS1) verschieden ist.

A method for transmitting an ultrasonic signal which has been further developed from the above method comprises the steps

1. a. generating the first ultrasonic partial burst with a first ultrasonic transducer (UBS1) and / or
2. b. generating the second ultrasound partial burst with a second ultrasound transducer (UBS2) which is different from the first ultrasound transducer (UBS1).

The first ultrasonic transducer ( US1 ) a first resonance frequency ( f ₁ ) and the second ultrasonic transducer ( US2 ) a second resonance frequency ( f ₂ ), where the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) from the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) is different. This allows additional information on the object classification of the objects ( O ) be used.

1. a. die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o ) minus dem Betrag der zweiten unteren Halbmaximalamplitudenfrequenz (f_2u ) bevorzugt größer ist als die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o ) minus dem Betrag der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u ) und /oder
2. b. die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o ) minus dem Betrag der der zweiten unteren Halbmaximalamplitudenfrequenz (f_2u ) bevorzugt größer ist als die Differenz des Betrags der zweiten oberen Halbmaximalamplitudenfrequenz (f_2o ) minus dem Betrag der der zweiten unteren Halbmaximalamplitudenfrequenz (f_2u ) oder
3. c. die Differenz des Betrags der zweiten oberen Halbmaximalamplitudenfrequenz (f_2o ) minus dem Betrag der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u ) bevorzugt größer ist als die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o ) minus dem Betrag der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u ) und /oder
4. d. die Differenz des Betrags der zweiten oberen Halbmaximalamplitudenfrequenz (f_2o ) minus dem Betrag der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u ) bevorzugt größer ist als die Differenz des Betrags der ersten oberen Halbmaximalamplitudenfrequenz (f_1o ) minus dem Betrag der der ersten unteren Halbmaximalamplitudenfrequenz (f_1u ).

The first ultrasonic transducer ( US1 ) a first bandwidth ( Δf ₁ ) with a first upper half-maximum amplitude frequency ( f _1o ) and a first lower half-maximum amplitude frequency ( f _1u ) on. The second ultrasonic transducer ( US1 ) preferably has a second bandwidth ( Δf ₂ ) with a second upper half-maximum amplitude frequency ( f _2o ) and a second lower half-maximum amplitude frequency ( f _2u ) on. The first bandwidth ( Δf ₁ ) and the second bandwidth ( Δf ₂ ) overlap in the frequency range. This has the advantage that a frequency sweep can be carried out over a larger frequency range. So it is preferred that

1. a. the difference in the amount of the first upper half-maximum amplitude frequency ( f _1o ) minus the amount of the second lower half-maximum amplitude frequency ( f _2u ) is preferably greater than the difference in the amount of the first upper half-maximum amplitude frequency ( f _1o ) minus the amount of the first lower half-maximum amplitude frequency ( f _1u ) and or
2. b. the difference in the amount of the first upper half-maximum amplitude frequency ( f _1o ) minus the amount of the second lower half-maximum amplitude frequency ( f _2u ) is preferably greater than the difference in the amount of the second upper half-maximum amplitude frequency ( f _2o ) minus the amount of the second lower half-maximum amplitude frequency ( f _2u ) or
3. c. the difference in the amount of the second upper half-maximum amplitude frequency ( f _2o ) minus the amount of the first lower half-maximum amplitude frequency ( f _1u ) is preferably greater than the difference in the amount of the first upper half-maximum amplitude frequency ( f _1o ) minus the amount of the first lower half-maximum amplitude frequency ( f _1u ) and or
4. d. the difference in the amount of the second upper half-maximum amplitude frequency ( f _2o ) minus the amount of the first lower half-maximum amplitude frequency ( f _1u ) is preferably greater than the difference in the amount of the first upper half-maximum amplitude frequency ( f _1o ) minus the amount of the first lower half-maximum amplitude frequency ( f _1u ).

Furthermore, it is advantageous if the angle-dependent first energy density of the first sound radiation of the first ultrasonic transducer ( US1 ) on the angle-dependent second energy density of the second sound radiation of the second ultrasonic transducer ( US2 ) is different and / or the angle-dependent first sound amplitude of the first sound radiation of the first ultrasonic transducer ( US1 ) from the angle-dependent second sound amplitude of the second sound radiation of the second ultrasonic transducer ( US2 ) is different. In this way, as explained in the figures, information about the angular range and the distance of an object can be obtained from the reflection signal ( O1 , O2 ) be won.

In addition to the previously described methods for transmitting ultrasonic bursts, there are also analogous methods for receiving the ultrasonic bursts.

1. a. des Empfangs des reflektierten Ultraschallsignals mit einem ersten Ultraschall-Transducer (US1) als erstes Ultraschallempfangssignal, wobei der erste Ultraschall-Transducer eine erste Resonanzfrequenz (f1) aufweist, und
2. b. des Empfangs des reflektierten Ultraschallsignals mit einem zweiten Ultraschall-Transducer (US2) als zweites Ultraschallempfangssignal, wobei der zweite Ultraschall-Transducer (US2) eine zweite Resonanzfrequenz (f2) aufweist, und
3. c. des Verarbeitens des ersten Ultraschallempfangssignals und des zweiten Ultraschallempfangssignals und
4. d. des Schließens auf Abstände von Objekten (O1, O2), die das Ultraschallsignal reflektiert haben, zu dem gemeinsamen Ultraschallsystem (USS) und
5. e. des Schließens auf einen Winkel zwischen der Sichtlinie von dem gemeinsamen Ultraschallsystem (USS) zu Objekten (O1, O2), die das Ultraschallsignal reflektiert haben, einerseits und der Ultraschallsystemachse (USA) des gemeinsamen Ultraschallsystems (USS) andererseits oder Schließen auf einen Winkelbereich in dem sich die Objekte (O1, O2) jeweils befinden.

The ultrasonic signal that is now received and that typically previously at an object was reflected, was previously preferably generated with the aid of one of the methods described above. The complex structure of the ultrasonic signals is discussed in more detail in the description of the figures. It is therefore recommended to briefly skim through the figures with the frequency curves in order to understand which type of ultrasonic bursts are to be received. A first ultrasonic transducer ( US1 ) and a second ultrasonic transducer ( US2 ) should be part of a common ultrasonic sensor system ( USS ) be. The ultrasonic sensor system ( USS ) should an ultrasound system axis ( United States ) exhibit. The method for receiving the complex ultrasonic bursts comprises the steps

1. a. the reception of the reflected ultrasonic signal with a first ultrasonic transducer ( US1 ) as a first ultrasonic received signal, the first ultrasonic transducer having a first resonance frequency (f1), and
2. b. the reception of the reflected ultrasonic signal with a second ultrasonic transducer ( US2 ) as the second ultrasound received signal, whereby the second ultrasound transducer ( US2 ) has a second resonance frequency (f2), and
3. c. processing the first ultrasonic reception signal and the second ultrasonic reception signal and
4. d. of inferring distances from objects ( O1 , O2 ), which have reflected the ultrasound signal, to the common ultrasound system ( USS ) and
5. e. of inferring an angle between the line of sight from the common ultrasound system ( USS ) to objects ( O1 , O2 ), which have reflected the ultrasound signal, on the one hand and the ultrasound system axis ( United States ) of the common ultrasound system ( USS ) on the other hand or close to an angular range in which the objects ( O1 , O2 ) respectively.

What has been written so far results in a method for determining an object position, the implementation of a method with the aid of the different sound cones of the different ultrasonic transducers ( US1 - US2 , US3 ) with the help of a first common ultrasound system ( USS1 ) to determine a first distance ( s1 ) and a first angle or first angle range and the analog implementation of this method with the aid of a preferably, but not necessarily structurally identical, second common ultrasound system ( USS2 ) from the first common ultrasound system ( USS1 ) different - i.e. not identical to this - and spaced apart, to determine a second distance ( s2 ) and a second angle or a second distance and second angle range. According to this method, a spatial coordinate or a spatial area in which an object ( O ) that reflected the ultrasonic signal based on the first distance ( s1 ) and the second distance ( s2 ), as well as the determined first angular range and the determined second angular range. The information associated with the first angular range and the first distance ( s1 ) correspond to a first spatial area approximately in the shape of a first torus at the first distance from the first ultrasonic sensor system ( USS1 ). The information given to the second angular range and the second distance ( s1 ) correspond to a second spatial area roughly in the shape of a second torus at a second distance from the second ultrasonic sensor system ( USS2 ). The intersection of the spatial points that are located both within the first spatial area and the second spatial area result in a further reduced spatial area in which the object in question should be located.

• - Schritt 1: Aussenden eines Ultraschallbursts mit einer Ultraschallburstdauer (bd), die eine maximale Ultraschallburstdauer (bd) nicht überschreitet, durch ein Ultraschallsensorsystem (USS);
• - Schritt 2: Empfangen eines durch ein Objekt (O) reflektierten Ultraschallbursts;
• - Schritt 3: Bestimmen des Abstands (D) zwischen dem Ultraschallsensorsystem (USS) und dem Objekt (O) in Abhängigkeit von dem empfangenen reflektierten Ultraschallburst;
• - Schritt 4: Wiederholen der Schritte 1 bis 4, wobei die Ultraschallburstdauer (bd) von dem ermittelten Abstand (s1, s2) abhängt.

Furthermore, a further method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles is disclosed, which comprises the following steps:

• - Step 1: sending an ultrasonic burst with an ultrasonic burst duration ( bd ), which have a maximum ultrasonic burst duration ( bd ) is not exceeded by an ultrasonic sensor system ( USS );
• - Step 2: Receiving a by an object ( O ) reflected ultrasonic bursts;
• - Step 3: Determine the distance ( D. ) between the ultrasonic sensor system ( USS ) and the object ( O ) as a function of the received reflected ultrasonic burst;
• - Step 4: Repeat steps 1 to 4, whereby the ultrasonic burst duration ( bd ) from the determined distance ( s1 , s2 ) depends.

mit bd₀ und bd₁ als Konstanten zeitlich verlängert wird, also betragsmäßig angehoben wird. Dies hat den Vorteil, dass die Gesamtenergie, die bei einer Reflektion zu dem aussendenden Ultraschall-Transducer zurückgelangt Rückschlüsse auf das Objekt zulässt, da diese Energiemenge nicht mehr von der Entfernung, sondern nur noch von Größe und Reflektivität des Objekts abhängt. Es reicht aus, wenn solche, in der Burst-Länge (bd) korrigierten Ultraschallpulse von Zeit zu Zeit ausgesendet werden. Sind beispielsweise mehrere Objekte in unterschiedlichen Abständen lokalisiert worden, so ist es möglicherweise sinnvoll, je erkanntem Objekt einen auf den Abstand dieses Objekts optimierten Ultraschall-Burst (UB) auszusenden.It has been shown that it is advantageous if the ultrasonic burst length ( bd ) with the fourth root of the determined distance ( D. ) according to the formula $$\text{bd}={\text{<figure-callout id="1" label="bd" filenames="DE102020008034A1\_0006.png,DE102020008034A1\_0012.png" state="{{state}}">bd</figure-callout>}}_1*{\text{D.}}^{-1/\mathrm{4th}}+{\text{<figure-callout id="0" label="bd" filenames="DE102020008034A1\_0006.png,DE102020008034A1\_0026.png" state="{{state}}">bd</figure-callout>}}_0$$

with bd ₀ and bd ₁ as constants is extended over time, i.e. is increased in terms of amount. This has the advantage that the total energy that is returned to the emitting ultrasonic transducer during a reflection allows conclusions to be drawn about the object, since this amount of energy no longer depends on the distance, but only on the size and reflectivity of the object. It is sufficient if those in the burst length ( bd ) corrected Ultrasonic pulses are sent out from time to time. If, for example, several objects have been localized at different distances, it may make sense to use an ultrasound burst optimized for the distance of this object ( UB ) to send out.

• - Schritt 1: Aussenden eines Ultraschallbursts mit einer Ultraschallbursteigenschaft durch ein Ultraschallsensorsystem (USS);
• - Schritt 2: Empfangen eines durch ein Objekt (O) reflektierten Ultraschallbursts;
• - Schritt 3: Bestimmen und Bewerten einer Eigenschaft des Objekts (O) in Abhängigkeit von dem empfangenen reflektierten Ultraschallburst und/oder ggf. mehreren empfangenen reflektierten Ultraschallbursts;
• - Schritt 4: Wiederholen der Schritte 1 bis 4, wobei zumindest eine Ultraschallbursteigenschaft eines nachfolgend ausgesendeten Ultraschallbursts von der Bewertung der ermittelten Eigenschaft abhängt.

This then results in a method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles with the following steps:

• - Step 1: sending an ultrasonic burst with an ultrasonic burst characteristic by an ultrasonic sensor system ( USS );
• - Step 2: Receiving a by an object ( O ) reflected ultrasonic bursts;
• - Step 3: Determine and evaluate a property of the object ( O ) as a function of the received reflected ultrasonic burst and / or possibly several received reflected ultrasonic bursts;
• Step 4: repeating steps 1 to 4, with at least one ultrasonic burst characteristic of a subsequently transmitted ultrasonic burst depending on the evaluation of the determined characteristic.

It is essential that one of the subsequently transmitted ultrasonic bursts does not have to immediately follow the preceding ultrasonic burst. Rather, it is conceivable to send further ultrasonic bursts that have other measuring tasks between these two ultrasonic bursts. Such sequences of ultrasonic bursts can be mixed. Thus, the ultrasonic burst characteristic of an ultrasonic burst to be transmitted can be derived from one or more objects in the vicinity of the ultrasonic sensor system ( USS ) or the environment of the ultrasonic sensor system ( USS ) depend. The ultrasonic burst characteristic of an ultrasonic burst to be emitted can therefore depend on one or more objects in the vicinity of a vehicle or on the surroundings of the vehicle if such an ultrasonic sensor system ( USS ) is installed in the vehicle. Several ultrasonic burst properties are described below, which can also affect the properties of several ultrasonic bursts.

• - Schritt 1: Aussenden eines ersten Ultraschallbursts mit einer Ultraschallbursteigenschaft mit einem ersten Ultraschallbursteigenschaftswert durch ein Ultraschallsensorsystem (USS);
• - Schritt 2: Empfangen eines durch ein erstes Objekt (O) reflektierten ersten Ultraschallbursts;
• - Schritt 3: Bestimmen und Bewerten einer ersten Eigenschaft des ersten Objekts (O1) in Abhängigkeit von dem empfangenen reflektierten ersten Ultraschallburst und/oder ggf. mehreren empfangenen reflektierten ersten Ultraschallbursts;
• - Schritt 4: Aussenden eines zweiten Ultraschallbursts mit der Ultraschallbursteigenschaft mit einem zweiten Ultraschallbursteigenschaftswert durch das Ultraschallsensorsystem (USS);
• - Schritt 5: Empfangen eines durch ein zweites Objekt (O) reflektierten zweiten Ultraschallbursts;
• - Schritt 6: Bestimmen und Bewerten einer zweiten Eigenschaft des zweiten Objekts (O2) in Abhängigkeit von dem empfangenen reflektierten zweiten Ultraschallburst und/oder ggf. mehreren empfangenen reflektierten zweiten Ultraschallbursts;
• - Schritt 7: Wiederholen der Schritte 1 bis 6,
  • ■ wobei zumindest die erste Ultraschallbursteigenschaft eines nachfolgend ausgesendeten ersten Ultraschallbursts von der Bewertung der ermittelten ersten Eigenschaft abhängt und
  • ■ wobei zumindest die zweite Ultraschallbursteigenschaft eines nachfolgend ausgesendeten zweiten Ultraschallbursts von der Bewertung der ermittelten zweiten Eigenschaft abhängt.

A method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles can then result, for example, that comprises the following steps:

• - Step 1: Emission of a first ultrasonic burst with an ultrasonic burst characteristic with a first ultrasonic burst characteristic value by an ultrasonic sensor system ( USS );
• - Step 2: Receiving a by a first object ( O ) reflected first ultrasonic bursts;
• - Step 3: determining and evaluating a first property of the first object ( O1 ) as a function of the received reflected first ultrasonic burst and / or possibly a plurality of received reflected first ultrasonic bursts;
• - Step 4: Emission of a second ultrasonic burst with the ultrasonic burst characteristic with a second ultrasonic burst characteristic value by the ultrasonic sensor system ( USS );
• - Step 5: Receiving one by a second object ( O ) reflected second ultrasonic bursts;
• - Step 6: determining and evaluating a second property of the second object ( O2 ) as a function of the received reflected second ultrasonic burst and / or possibly a plurality of received reflected second ultrasonic bursts;
• - Step 7: Repeat steps 1 to 6,
  • Where at least the first ultrasonic burst characteristic of a subsequently transmitted first ultrasonic burst depends on the evaluation of the determined first characteristic, and
  • At least the second ultrasonic burst characteristic of a subsequently transmitted second ultrasonic burst depends on the evaluation of the determined second characteristic.

It is important that further ultrasonic bursts can be inserted here for other purposes. First ultrasonic bursts can also be transmitted more frequently or less frequently in comparison to the second ultrasonic bursts.

So how the ultrasonic burst duration ( bd ) can be optimized as a function of the object, the ultrasonic burst amplitude can also be optimized as a function of the object. So it can make sense if the amplitude ( A. ) of at least three ultrasonic bursts emitted in immediate or non-immediate chronological sequence, essentially proportional to (D + D ₀ ) ^{1 / k} , with 2≤k≤5 or preferably k = 2 or k = 4, from the determined distance ( A. ), where D _{0 is} a constant that can be zero. Here, between these ultrasonic bursts ( UB ) further ultrasonic bursts ( UB ) to measure other objects and environmental properties.

Typically, several ultrasonic bursts ( UB ) emitted in a temporal ultrasonic burst interval, the first temporal ultrasonic burst interval being the interval between the ultrasonic burst start ( UBS ) of a first ultrasonic burst and the ultrasonic burst start ( UBS ) of is the second ultrasonic burst immediately following this first ultrasonic burst and between the ultrasonic burst start ( UBS ) of a first ultrasonic burst and the ultrasonic burst start ( UBS ) of the second ultrasonic burst immediately following this first ultrasonic burst and where the second temporal ultrasonic burst interval between the ultrasonic burst start ( UBS ) of the second ultrasonic burst and the ultrasonic burst start ( UBS ) of the third ultrasonic burst immediately following this second ultrasonic burst from the determined distance ( D. ) of an object ( O , O , O2 ) depends.

Another possible variation of an ultrasound burst characteristic is a variation of the ultrasound burst interval of the ultrasound bursts over time. The temporal ultrasonic burst interval of the ultrasonic bursts can, for example, with decreasing spatial distance ( D. ) between the ultrasonic sensor system and the object ( O ) become shorter in time. The temporal ultrasonic burst spacing of the ultrasonic bursts is preferred with a shortening of the spatial spacing ( D. ) between the ultrasonic sensor system and the object ( O ) by a length I temporally by a time 2 * I / c with c as the speed of sound with a tolerance of +/- 25% and / or better with a tolerance of +/- 10% and / or better with a tolerance of + / - 5% shorter.

The number of instantaneous ultrasonic _burst frequencies (f m1, f _m2 , f _m3 ) and the associated number of frequency curves ( SF1 , SF2 , SF3 ) of these instantaneous ultrasonic _burst frequencies (f m1, f _m2 , f _m3 ) within an ultrasonic burst ( UB ) from the distance ( D. ) depend.

• • eine Single-Mode-Zeit (smt₁ , smt₂ , smt₃ , smt1, smt2) und/oder
• • eine Dual-Mode-Zeit (dmt₁₂ , dmt₂₃ , dmt1, dmt2) und/oder
• • eine Tri-Mode-Zeit (t_mt, tmt₁₂₃, tmt₁₁₂).

Another modification of an ultrasound burst property can be that an ultrasound burst has at least two of the following types of time segments:

• • a single mode time ( smt ₁ , smt ₂ , smt ₃ , smt1, smt2) and / or
• • a dual mode time ( dmt ₁₂ , dmt ₂₃ , dmt1, dmt2) and / or
• • a tri-mode time (t _mt , tmt ₁₂₃ , tmt ₁₁₂ ).

This ultrasonic burst property can also depend on objects in the surroundings or the surroundings in parts or as a whole. Such ultrasonic sensor systems are preferably used in vehicles. It is then preferably an ultrasonic sensor system ( USS ) for a vehicle, with a first ultrasonic transducer ( US1 ), with a second ultrasonic transducer ( US2 ). Of course, the ultrasonic sensor system can also have more than two ultrasonic transducers ( US1 , US2 , US3 ) exhibit. In our example, the first ultrasonic transducer ( US1 ) a first resonance frequency ( f ₁ ) and the second ultrasonic transducer ( US2 ) a second resonance frequency ( f ₂ ), where the first resonance frequency ( f ₁ ) from the second resonance frequency ( f ₂ ) is different.

The first ultrasound transducer preferably has ( US1 ) a first bandwidth ( Δf ₁ ) and the second ultrasonic transducer ( US2 ) a second bandwidth ( Δf ₂ ). So that a chirp can be carried out over the full bandwidth without significant amplitude drops, it makes sense if the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) and the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) overlap.

The ultrasonic sensor system is preferred ( USS ) designed so that the ultrasonic sensor system ( USS ) an ultrasonic burst ( UB ) with one of the time ( t ) dependent ultrasonic burst instantaneous frequency ( f _m ) that can emit at least one point in time during the emission of the ultrasonic burst ( UB ) from an ultrasonic transducer the ultrasonic transducer ( US1 , US2 ) of the ultrasonic sensor system ( USS ) cannot be emitted. This therefore describes an increase in bandwidth compared to a single ultrasonic transducer with regard to the emission.

In analogy to this, the ultrasonic sensor system is preferred ( USS ) designed so that the ultrasonic sensor system ( USS ) an ultrasonic burst ( UB ) with one of the time ( t ) dependent ultrasonic burst instantaneous frequency ( f _m ) that at least one point in time during the emission of the ultrasonic burst ( UB ) from an ultrasonic transducer the ultrasonic transducer ( US1 , US2 ) of the ultrasonic sensor system ( USS ) cannot be received. This therefore describes an increase in bandwidth compared to a single ultrasonic transducer with regard to reception.

The ultrasonic sensor system ( USS ) an ultrasonic burst ( UB ) that has more than one instantaneous ultrasonic _burst frequency (f m1, f _m2 , f _m3 ) in its spectrum, each of the instantaneous ultrasonic _burst frequencies (f m1, f _m2 , f _m3 ) during of such an ultrasonic burst essentially in the bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) at least one of the ultrasonic transducers ( US1 , US2 , US3 ) lies. This, too, is an ultrasound burst characteristic that is generated by the examination target, typically an object ( O , O1 , O2 ) in the vicinity of the ultrasonic sensor system or the vehicle. Conversely, the ultrasonic sensor system ( USS ) then typically an ultrasonic burst ( UB ), which has more than one ultrasonic _{burst instantaneous} frequency (f m1, f _m2 , f _m3 ) in its spectrum, each of the ultrasonic _{burst instantaneous} frequencies (f m1, f _m2 , f _m3 ) during such an ultrasonic burst essentially in the bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) at least one of the ultrasonic transducers ( US1 , US2 , US3 ) lies. The output signals of the ultrasonic transducers are then preferably combined to form an ultrasonic reception signal. In the simplest case, this can be done, for example, by adding up the output signals of the ultrasonic transducers.

Also an ultrasonic sensor system ( USS ) conceivable in which the ultrasonic sensor system ( USS ) an ultrasonic burst ( UB ) that can receive more than one _{instantaneous ultrasonic burst frequency (f m1} , f _m2 , f _m3 ) in its spectrum at at least one point in time during the burst duration ( bd ) having,
where each of the instantaneous ultrasonic _burst frequencies (f m1, f _m2 , f _m3 ) during such an ultrasonic burst is essentially in the bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) at least one of the ultrasonic transducers ( US1 , US2 , US3 ) and at least one of these instantaneous ultrasonic _burst frequencies (f m1, f _m2 , f _m3 ) during such an ultrasonic burst at least at one point in time not in the bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) at least one of the ultrasonic transducers ( US1 , US2 , US3 ) lies. The use of several ultrasonic transducers therefore increases the bandwidth with regard to reception.

In one possible configuration, several ultrasonic transducers ( US1 , US2 ) an ultrasonic sensor system ( USS ) by means of a common control signal ( AS ) driven. This has the advantage that such an ultrasonic sensor system ( USS ) behaves essentially like a single ultrasonic transducer for controlling circuits.

In a similar way, the output signals of the ultrasonic transducer ( US1 , US2 ) a common ultrasonic reception signal can be generated that can also have several partial signals.

Such an ultrasonic sensor system ( USS ) can be designed so that the sound radiation lobe of the first ultrasonic transducer ( US1 ) a first vertical opening angle (α _V ) and the sound radiation lobe of the second ultrasonic transducer ( US2 ) has a second vertical opening angle (β _V ) or that the receiving lobe of the first ultrasonic transducer ( US1 ) a first vertical opening angle (α _V ) and the receiving lobe of the second ultrasonic transducer ( US2 ) has a second vertical opening angle (β _V ). The first vertical opening angle (α _V ) should then be different from the second vertical opening angle (β _V ) so that a reflected ultrasonic signal has different frequencies that encode the angular range around the axis ( United States ) of the ultrasonic sensor system ( USS ) the reflective object may be located.

The sound radiation lobe of the first ultrasonic transducer ( US1 ) a first horizontal opening angle (α _H ) and the sound radiation lobe of the second ultrasonic transducer ( US2 ) a second vertical opening angle (β _V ) on or the receiving lobe of the first ultrasonic transducer ( US1 ) a first horizontal opening angle (α _H ) and the receiving lobe of the second ultrasonic transducer ( US2 ) a second vertical opening angle (β _V ). Here, too, the first horizontal opening angle (α _H ) is preferably different from the second vertical opening angle (β _V ), which results in an analogous advantage.

The proposed ultrasonic sensor system very particularly preferably points to the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) still further ultrasonic transducers, so that an ultrasonic transducer array is obtained in which the ultrasonic transducers ( US1 , US2 , US3 ) different resonance frequencies ( f ₁ , f ₂ , f ₃ ) exhibit. In the simplest case, the proposed ultrasonic sensor system points to the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) a third ultrasonic transducer ( US3 ), the third ultrasonic transducer ( US3 ) a third resonance frequency ( f ₃ ), which preferably depends on the second resonance frequency ( f ₂ ) and from the first resonance frequency ( f ₁ ) is different.

In this case with three ultrasonic transducers ( US1 , US2 , US3 ) are the ultrasonic transducers ( US1 , US2 , US3 ) preferably arranged in an isosceles triangle. The edge lengths of this isosceles triangle are preferably less than ten times the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) and / or better than five times the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) and / or better than three times the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) and / or better smaller than twice the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ).

• • Empfangen des Ultraschallgesamtbursts (UB), mittels eines Ultraschallsensorsystems (USS) mit zumindest einem ersten Ultraschall-Transducer (US1) und einem zweiten Ultraschall-Transducer (US2), wobei der erste Ultraschall-Transducer (US1) eine erste Resonanzfrequenz (f₁ ) und eine erste Bandbreite (Δf₁ ) aufweist und wobei der zweite Ultraschall-Transducer (US2) eine zweite Resonanzfrequenz (f₂ ) und eine zweite Bandbreite (Δf₂ ) aufweist und wobei die erste Resonanzfrequenz (f₁ ) von der zweiten Resonanzfrequenz (f₂ ) verschieden ist und wobei die erste Bandbreite (Δf₁ ) die zweite Bandbreite (Δf₂ ) überlappt und wobei der erste Ultraschalltransducer (US1) ein erstes Ultraschallempfangsteilsignal erzeugt und wobei der zweite Ultraschalltransducer (US2) ein zweites Ultraschallempfangsteilsignal erzeugt;
• • Erzeugen eines Ultraschallempfangssignals aus dem ersten Ultraschallempfangsteilsignal und dem zweiten Ultraschallempfangsteilsignal, wobei das Ultraschallempfangssignal mehrere Teilempfangssignale umfassen kann und wobei ein oder mehrere Teilempfangssignale mit Ultraschallempfangsteilsignalen übereinstimmen können;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals.

In an analogous manner, there is a method for receiving an ultrasonic signal, the ultrasonic signal being a total ultrasonic burst ( UB ), which comprises a first ultrasonic partial burst and a second ultrasonic partial burst. Each partial ultrasonic burst of the partial ultrasonic bursts here also includes at least two ultrasonic pulses ( P ₀ until P ₇ ), each of which has at least two ultrasonic pulses ( P ₀ until P ₇ ) of an ultrasound partial burst has a temporal ultrasound pulse start and a temporal ultrasound pulse end. As before, here is the one Ultrasonic period ( T ₁ until T ₇ ) of a single ultrasonic pulse ( P ₀ until P ₇ ) of a partial ultrasound burst, hereinafter referred to as the relevant ultrasound pulse, the time from the temporal ultrasound pulse end of the ultrasound pulse immediately preceding the relevant ultrasound pulse to the temporal ultrasound pulse end of the relevant ultrasound pulse. The first ultrasonic instantaneous frequency ( f _1m ) of the first partial ultrasonic burst is again the reciprocal of the instantaneous ultrasonic period (T _1m ) of the first partial ultrasonic burst and the second ultrasonic instantaneous frequency ( f _2m ) of the second partial ultrasound burst is again the reciprocal of the instantaneous ultrasound period (T _2m ) of the second partial ultrasound burst. The first partial ultrasound burst begins at a first start time ( t _1s ), which is equal to the start of the ultrasound pulse of the first ultrasound pulse ( P ₀ ) of the first partial ultrasound burst. The first partial ultrasound burst ends at a first end time ( t _1e ), which is equal to the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the first partial ultrasonic burst. The first ultrasonic partial burst has a first ultrasonic partial burst duration ( t _1e - t _1s ), which corresponds to the value of the time difference between the first end time ( t _1e ) minus the first start time ( t _1s ) is equivalent to. The second partial ultrasound burst begins at a second start time ( t _2s ), which is equal to the start of the ultrasound pulse of the first ultrasound pulse ( P ₀ ) of the second ultrasonic partial burst. The second partial ultrasound burst ends at a second end time ( t _2e ), which is equal to the end of the ultrasonic pulse of the last ultrasonic pulse (P7) of the second partial ultrasonic burst. The second partial ultrasound burst has a second partial ultrasound burst _{duration (bd = t 2e} -t _2s ), which corresponds to the value of the time difference between the second end time ( t _2e ) minus the second start time ( t _2s ) is equivalent to. The first ultrasonic instantaneous frequency ( f _1m ) is preferably of the second instantaneous ultrasonic frequency ( f _2m ) at least one time between the first start time ( t _1s ) and the first end time ( t _1e ) and at the same time between the second start time ( t _2s ) and the second end time ( t _2e ) different. The reception process then comprises the following steps:

• • Receiving the total burst of ultrasound ( UB ), by means of an ultrasonic sensor system ( USS ) with at least one first ultrasonic transducer ( US1 ) and a second ultrasonic transducer ( US2 ), where the first ultrasonic transducer ( US1 ) a first resonance frequency ( f ₁ ) and a first bandwidth ( Δf ₁ ) and wherein the second ultrasonic transducer ( US2 ) a second resonance frequency ( f ₂ ) and a second bandwidth ( Δf ₂ ) and wherein the first resonance frequency ( f ₁ ) from the second resonance frequency ( f ₂ ) is different and where the first bandwidth ( Δf ₁ ) the second bandwidth ( Δf ₂ ) overlaps and where the first ultrasonic transducer ( US1 ) generates a first ultrasound receiving sub-signal and wherein the second ultrasound transducer ( US2 ) generating a second ultrasonic receiving sub-signal;
• • Generating an ultrasonic received signal from the first ultrasonic receiving sub-signal and the second ultrasonic receiving sub-signal, wherein the ultrasonic receiving signal can comprise a plurality of sub-received signals and wherein one or more sub-received signals can coincide with ultrasonic receiving sub-signals;
• • Determination of environmental information on the basis of the ultrasonic reception signal.

Typically, at least one point in time during the burst duration ( bd ) of the total ultrasonic burst is the first instantaneous ultrasonic frequency ( f _1m ) not within the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ), but within the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ), and / or the first ultrasonic instantaneous frequency ( f _1m ) not within the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ), but within the first range ( Δf ₁ ) of the first ultrasonic transducer ( US1 ), the second instantaneous ultrasonic frequency ( f _2m ) not within the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ), but within the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ), and / or the second ultrasonic instantaneous frequency ( f _2m ) not within the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) but within the first range ( Δf ₁ ) of the first ultrasonic transducer ( US1 ).

A refinement of the method can include the step of inferring a distance to an object ( O1 , O2 ) and an angular range in which this object ( O1 , O2 ) is located due to differences between the first ultrasonic receiving sub-signal and the second ultrasonic receiving sub-signal or due to differences in signals derived therefrom. In particular, neural networks or other pattern recognition methods can be used for this.

• • eine Single-Mode-Zeit (smt₁ , smt₂ , smt₃ , smt1, smt2) und/oder
• • eine Dual-Mode-Zeit (dmt₁₂ , dmt₂₃ , dmt1, dmt2) und/oder
• • eine Tri-Mode-Zeit (t_mt, tmt₁₂₃, tmt₁₁₂)

The method for receiving a total ultrasound burst can be characterized in that a received total ultrasound burst has at least two of the following types of time segments:

• • a single mode time ( smt ₁ , smt ₂ , smt ₃ , smt1, smt2) and / or
• • a dual mode time ( dmt ₁₂ , dmt ₂₃ , dmt1, dmt2) and / or
• • a tri-mode time (t _mt , tmt ₁₂₃ , tmt ₁₁₂ )

• • Empfang des Ultraschallgesamtbursts und Erzeugung des besagten Ultraschallempfangssignals, das mehrere Teilempfangssignale umfassen kann;
• • Feststellen der ersten Zeitabschnittsart zu einem ersten Zeitpunkt innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals in Abhängigkeit von der festgestellten ersten Zeitabschnittsart.

Under this prerequisite, the method can then include the following steps, among others:

• • Receiving the total ultrasound burst and generating said ultrasound reception signal, which may comprise a plurality of partial reception signals;
• • Determination of the first time segment type at a first point in time within the burst duration ( bd ) of the total burst of ultrasound;
• • Determination of information about the surroundings on the basis of the ultrasound received signal as a function of the first type of time segment that has been determined.

• • Feststellen der zweiten Zeitabschnittsart zu einem zweiten Zeitpunkt innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts, der vom ersten Zeitpunkt verschieden ist;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals in Abhängigkeit von der festgestellten ersten Zeitabschnittsart innerhalb eines ersten Zeitabschnitts innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts;
• • Ermitteln von Umfeldinformationen auf Basis des Ultraschallempfangssignals in Abhängigkeit von der festgestellten zweiten Zeitabschnittsart innerhalb eines zweiten Zeitabschnitts innerhalb der Burstdauer (bd) des Ultraschallgesamtbursts,

This process can be refined to include the following steps:

• • Determination of the second type of time segment at a second point in time within the burst duration ( bd ) the total burst of ultrasound, which is different from the first point in time;
• • Determination of environmental information on the basis of the ultrasonic received signal as a function of the determined first time segment type within a first time segment within the burst duration ( bd ) of the total burst of ultrasound;
• • Determination of environmental information on the basis of the ultrasonic received signal as a function of the determined second time segment type within a second time segment within the burst duration ( bd ) of the total burst of ultrasound,

The first time segment and the second time segment should preferably not overlap. At least they shouldn't completely overlap.

Ultrasound transducers have always been used in this document. It is obvious to the person skilled in the art that, with regard to the transmission of the total ultrasound bursts, it is also possible to use ultrasound transmitters which are only used and / or suitable for transmission of the total ultrasound bursts. It is also obvious to the person skilled in the art that, with regard to the reception of the total ultrasound bursts, it is also possible to use ultrasound receivers which are only used and / or suitable for receiving the total ultrasound bursts. In this respect, the claims with regard to reception with the term ultrasound transducer also include combinations of ultrasound transducers with one or more pure ultrasound receivers and with regard to the transmission of total bursts of ultrasound with the term ultrasound transducer also combinations of ultrasound transducers with one or more pure ultrasound transmitters.

In the extreme case, it can only be a pure ultrasonic receiver or only a pure ultrasonic transmitter.

For example, it is conceivable to combine one or a few ultrasonic transducers that are used for transmitting and receiving with a larger number of pure ultrasonic receivers. The pure ultrasound receivers can be manufactured inexpensively on a MEMS basis, while the ultrasound transmitters can be built in the form of ultrasonic transducers in the form of piezo-based oscillating ceramics.

On this basis, an ultrasonic sensor system ( USS ), in particular for a vehicle or a robot or another mobile machine, which has a first, typically smaller number of ultrasonic transmitters and / or ultrasonic transducers, each of which has a piezoceramic as a sound-generating transmission element, and which has a second number of pure ultrasound receivers. At least one of these one ultrasound receivers is preferably a MEMS-based ultrasound receiver. The number of pure MEMS ultrasound receivers is very particularly preferably particularly high. At least some of the ultrasound transmitters and / or ultrasound transducers and / or ultrasound receivers preferably form an ultrasound system, as described above.

advantage

Such an ultrasonic sensor system ( USS ) enables, at least in some implementations, the transmission and / or reception of more complex ultrasonic bursts than are possible with individual ultrasonic transducers and / or ultrasonic transmitters and / or ultrasonic transmitters. This is particularly important in the course of creating maps and point clouds of the environment for autonomous driving. The advantages are not limited to this.

Figure list

• 1a as part of the 1 shows the course of the ultrasonic burst amplitude ( A. ) depending on the burst duration ( bd ).
• 1b as part of the 1 shows a suggested burst duration depending on the object distance ( D. ) to the next object.
• 1c as part of the 1 shows the ultrasonic burst amplitude ( A. ) depending on the object distance ( D. ).
• 2a shows, in simplified form, the temporal signal curve of a single, selected exemplary ultrasonic burst ( UB ).
• 2 B shows the associated temporal course of the instantaneous ultrasonic burst frequency ( f _m ) plotted against time ( t ) over the burst duration ( bd ).
• 2c 2c shows an example of the frequency change rate ( v _f ) the instantaneous ultrasonic burst frequency ( f _m ) over time ( t ) the burst duration ( bd ).
• 3 shows an exemplary first spectral ultrasonic burst amplitude ( A1 ) of a first ultrasonic transducer ( US1 ) for the amplitude ( A. ) the sound radiation of one of these ultrasonic transducers ( US1 ) with excitation with a first excitation signal with the first excitation frequency ( f _A1 ).
• 4th shows an exemplary, second spectral ultrasonic burst amplitude ( A2 ) for the amplitude ( A. ) the sound radiation of a second ultrasonic transducer ( US2 ) with excitation with a second excitation signal ( AS2 ) with the second excitation frequency ( f _A2 ).
• 5 5 shows an exemplary third spectral ultrasonic burst amplitude ( A3 ) for the amplitude ( A. ) the sound radiation of a third ultrasonic transducer ( US3 ) when excited with a transmission signal of the third excitation frequency (fA3).
• 6th 6th shows an example of the superposition of a first, second and third amplitude spectrum in two extreme configurations.
• 7th until 10 basically show possible types of a frequency sweep.
• 11 shows an exemplary arrangement consisting of a first ultrasonic transducer ( US1 ) and a second ultrasonic transducer ( US2 ) and a third ultrasonic transducer ( US3 ).
• 12th equals to 7th with the difference that now a frequency sweep with the help of three ultrasonic sensors ( US1 , US2 , US3 ) is produced.
• 13th shows, in a simplified and schematic manner, an exemplary system for generating the exemplary frequency response of FIG 12th .
• 14th corresponds in essential parts to 12th , but now the excitation signal ( AS ) at times includes more than one excitation frequency (fA).
• 15th shows, in a simplified and schematic manner, an exemplary system for generating the exemplary frequency response of the following 16 .
• 16 equals to 12th with the difference that now a first frequency curve ( SF1 ), a second frequency curve ( SF2 ) and a third frequency curve ( SF3 ) together to generate an ultrasonic burst ( UB ) be used.
• 17th equals to 16 with the difference that now all frequency curves ( SF1 , SF2 , SF3 ) end at a common end frequency (f _e ) as the respective _{instantaneous ultrasonic frequency (f m1} , f _m2 , f _m3 ) at a common end time (t _e ).
• 18th and 19th The sound radiation of an ultrasonic sensor system ( USS ) with different resonance frequencies and opening angles.
• 20th illustrates how the different types of modulation described above can now be used when approaching an important object ( O ), for example an obstacle, can be used.
• 21 illustrates the situation when using two ultrasonic sensor systems ( USS1 , USS2 )
• 22nd shows the course of the instantaneous ultrasound frequencies and their effect on the Doppler strength.

Description of the figures

Figure 1

1 shows in 1a the course of the ultrasonic burst amplitude ( A. ) depending on the burst duration ( bd ) (see also 2 ). As the ultrasonic burst becomes longer, i.e. the bust duration becomes longer ( bd ) the ultrasonic burst amplitude decreases ( A. ) away.

1b shows a suggested burst duration depending on the object distance ( D. ) to the next object. The burst duration is not only increased with increasing object distance ( D. ). The ultrasonic burst length (BD) preferably increases with the square root or the fourth root of the object distance ( D. ). On the one hand, this increases the latency time. The signal reflected by the object is increased in such a way that the reduction in the reception amplitude, which goes ^{with 1 / D 4} , is improved ^{to a reduction of 1 / D 2.} The ultrasonic burst length ( bd ) with the fourth root of the distance according to the formula bd = bd ₁ * D ^-1/4 + bd ₀ with bd ₀ and bd ₁ as constants. As a result, the total signal amplitude remains constant after reception and correlation in a correlator for the object to be measured.

In order to avoid overdrive in the close range, the burst duration ( bd ) in the vicinity of the Object not just lowered. The ultrasonic burst amplitude in the vicinity of the object is preferably also reduced. As a result, the reception amplitude can still be kept constant after reception and correlation have taken place even if a shortening of the burst duration ( bd ) no longer makes sense. It is therefore proposed here to determine the burst duration of the ultrasonic bursts and the ultrasonic burst amplitude ( A. ) readjust so that the reception amplitude of the observed object remains constant or follows a specified sensitivity curve. 1c shows the ultrasonic burst amplitude ( A. ) depending on the object distance ( D. ).

Figure 2

2a shows, in simplified form, the temporal signal curve of a single, selected exemplary ultrasonic burst ( UB ). The ultrasonic burst ( UB ) begins at the time of the ultrasonic burst start ( UBS ). The ultrasonic burst ( UB ) ends at the time of the end of the ultrasonic burst ( UBE ). The time between the ultrasonic burst start ( UBS ) and ultrasonic burst end ( UBE ) is the burst duration (BD). The ultrasonic burst ( UB ) has an ultrasonic burst amplitude ( A. ), which here as the mean amplitude of the ultrasonic burst ( UB ) over the burst duration (BD) of the relevant ultrasonic burst ( UB ) can be understood.

In 2b ist der zugehörige zeitliche Verlauf der Ultraschallburstmomentanfrequenz (f_m ) gegen die Zeit (t) über die Burst-Dauer (bd) skizzen- und beispielhaft aufgetragen. In dem Beispiel der 2b steigt durch den Beginn des Ultraschallbursts (UB) zum Zeitpunkt des Ultraschallburststarts (UBS) die Ultraschallburstmomentanfrequenz (f_m ) sprunghaft an. In dem Beispiel der 2a wird die Ultraschallburstmomentanfrequenz (f_m ) dann bevorzugt zumindest zeitweise einer Hyperbel folgend kontinuierlich bis zum Ultraschallburstende (UBE) abgesenkt.In the example of the 2a the ultrasonic burst shown there has ( UB ) eight ultrasound periods with one ultrasound pulse each, i.e. here as an example eight ultrasound pulses ( P ₀ until P ₇ ). The zeroth ultrasound pulse ( P ₀ ) is assigned to the only half existing zero ultrasound period. The ultrasound periods ( P ₀ until P ₇ ) of the ultrasonic burst ( UB ) have eight ultrasound periods ( T ₀ until T ₇ ) on. The zeroth ultrasound period ( T ₀ ) is used in the sense of this document as double the temporal pulse width of the zeroth ultrasonic pulse ( P ₀ ) Are defined. Below the instantaneous ultrasonic frequency (f _jm ) of the j-th ultrasonic pulse ( P _j ) the jth ultrasound period in this document is the reciprocal of the jth ultrasound period ( T _j ) of the j-th ultrasound period. $${ƒ}_{\text{j}}=\frac{1}{T_{\text{j}}}$$

In 2 B is the associated temporal course of the instantaneous ultrasonic burst frequency ( f _m ) against the time ( t ) over the burst duration ( bd ) applied in sketches and examples. In the example of the 2 B increases due to the beginning of the ultrasonic burst ( UB ) at the time of the ultrasonic burst start ( UBS ) the instantaneous ultrasonic burst frequency ( f _m ) by leaps and bounds. In the example of the 2a the ultrasonic burst instantaneous frequency ( f _m ) then preferably at least temporarily following a hyperbola continuously up to the end of the ultrasonic burst ( UBE ) lowered.

2c shows an example of the frequency change rate ( v _f ) the instantaneous ultrasonic burst frequency ( f _m ) over time ( t ) the burst duration ( bd ). At the beginning the frequency increases with a large positive frequency change rate ( v _f ) as a result of the ultrasonic burst start ( UBS ) from 0 Hz. The rate of change of frequency ( v _f ) is then strongly negative for a short time in this example and then increases linearly in this example. The amount of frequency change rate ( v _f ) decreases linearly in this example.

Figure 3

3 is used here to explain basic terms for the understanding of terms that are in this document find use to explain. 3 shows an exemplary first spectral ultrasonic burst amplitude ( A1 ) of a first ultrasonic transducer ( US1 ) for the amplitude ( A. ) the sound radiation of one of these ultrasonic transducers ( US1 ) with excitation with a first excitation signal with the first excitation frequency ( f _A1 ). The exemplary first spectral ultrasonic burst amplitude ( A1 ) has a first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at a first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) on. The exemplary first ultrasonic transducer ( US1 ) in the example of 3 a first bandwidth ( Δf ₁ ) the first spectral ultrasonic burst amplitude ( A1 ) for the amplitude ( A. ) the sound radiation of a first ultrasonic transducer ( US1 ) on. This first bandwidth ( Δf ₁ ) a first spectral ultrasonic burst amplitude ( A1 ) for the amplitude ( A. ) the first sound emission of a first ultrasonic transducer ( US1 ) defined here in such a way that this first bandwidth ( Δf ₁ ) of the first ultrasonic sensor ( US1 ) the first upper half-maximum amplitude frequency ( f _1o ), where the amplitude ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ) minus the first lower half-maximum amplitude frequency ( f _1u ), where the amplitude ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) also half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ) is.

Figure 4

4th is used here to explain basic terms for the understanding of terms that are used in this document. 4th shows an exemplary, second spectral ultrasonic burst amplitude ( A2 ) for the amplitude ( A. ) the sound radiation of a second ultrasonic transducer ( US2 ) with excitation with a second excitation signal ( AS2 ) with the second excitation frequency ( f _A2 ). The exemplary second spectral ultrasonic burst amplitude ( A2 ) has a second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at a second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) on. The exemplary second ultrasonic transducer ( US2 ) in the example of 4th a second bandwidth ( Δf ₂ ) the second spectral ultrasonic burst amplitude ( A2 ) for the amplitude ( A. ) the sound radiation of a second ultrasonic transducer ( US2 ) on. This second range ( Δf ₂ ) a second amplitude spectrum ( A2 ) for the amplitude ( A. ) the second sound emission of a second ultrasonic transducer ( US2 ) defined here in such a way that this second bandwidth ( Δf ₂ ) of the second ultrasonic sensor ( US2 ) the second upper half-maximum amplitude frequency ( f _2o ), where the amplitude ( A. ) the sound radiation of the second ultrasonic transducer ( US2 ) half of the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ) minus the second lower half-maximum amplitude frequency ( f _2u ), where the amplitude ( A. ) the sound radiation of the second ultrasonic transducer ( US2 ) also half of the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ) is.

Figure 5

5 is also used here to explain basic terminology for understanding terms that are used in this document. 5 shows an exemplary third spectral ultrasonic burst amplitude ( A3 ) for the amplitude ( A. ) the sound radiation of a third ultrasonic transducer ( US3 ) with excitation with a transmission signal of the third excitation frequency ( f _A3 ). The exemplary third spectral ultrasonic burst amplitude ( A3 ) has a third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at a third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) on. The exemplary third ultrasonic transducer ( US3 ) in the example of 5 a third bandwidth ( Δf ₃ ) the third spectral ultrasonic burst amplitude ( A3 ) for the amplitude ( A. ) the sound radiation of a third ultrasonic transducer ( US3 ) on. This third range ( Δf ₃ ) a third spectral ultrasonic burst amplitude ( A3 ) for the amplitude ( A. ) the third sound emission of a third ultrasonic transducer ( US3 ) defined here in such a way that this third bandwidth ( Δf ₃ ) of the third ultrasonic sensor ( US3 ) the third upper half-maximum amplitude frequency ( f _3o ), where the amplitude ( A. ) the sound radiation of the third ultrasonic transducer ( US3 ) half of the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ) minus the third lower half-maximum amplitude frequency ( f _3u ), where the amplitude ( A. ) the sound radiation of the third ultrasonic transducer ( US3 ) also half of the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ) is.

Figure 6

6th shows as an example in two extreme configurations the superposition of a first amplitude spectrum in the form of a first spectral ultrasonic burst amplitude ( A1 ) of a first ultrasonic transducer ( US1 ) and a second amplitude spectrum in the form of a second spectral ultrasonic burst amplitude ( A2 ) a second ultrasonic transducer ( US2 ) and a third amplitude spectrum in the form of a third spectral ultrasonic burst amplitude ( A3 ) a third ultrasonic transducer ( US3 ).

Figure 6a

In the 6a is the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer (US12) smaller than the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ).

In addition, the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer (US12) smaller than the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ).

Furthermore, the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) less than half of the sum of the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) and the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 )

In the 6a is also the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) smaller than the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ).

In addition, the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) smaller than the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

Furthermore, the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) less than half of the sum of the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

In the example of the 6a is also the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) roughly equal to the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

In the example of the 6a is the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) roughly equal to the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ).

The advantage of choosing the parameters of the various ultrasonic transducers lies in the possible combination of the three ultrasonic transducers exemplified here ( US1 , US2 , US3 ) to a single ultrasonic transducer system of increased width. Instead of the ultrasonic transducers, it is also possible in an analogous manner to use ultrasonic transmitters for transmitting and ultrasonic receivers for receiving ultrasonic bursts. In other words, the transmission function can be separated from the reception function in terms of equipment. If ultrasonic receivers are used instead of the ultrasonic transducers, the reception bandwidth of the overall system is also spread in an analogous manner, which enables many advantages.

For example, it is possible to generate an ultrasonic burst as an ultrasonic signal by such an ultrasonic sensor system ( USS ) whose required frequency bandwidth is the total frequency bandwidth ( Δf _g ) of the ultrasonic sensor system ( USS ) with several ultrasonic transducers ( US1 , US2 , US3 ) fully exploited. In the example, the 6a the exemplary total frequency bandwidth ( Δf _g ) of the ultrasonic sensor system ( USS ) from the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) and the third ultrasonic transducer ( US3 ) larger than the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) and larger than the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and larger than the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

This makes it possible for a first one of the ultrasonic transducers to emit more than 50% of the sound energy at a first frequency and a second of the ultrasonic transducers to emit less than 50% of the sound energy at this first frequency at a first point in time during the emission of an ultrasonic burst At a second point in time during the emission of the ultrasonic burst, the first of the ultrasonic transducers emits less than 50% of the sound energy at a second frequency and the second of the ultrasonic transducers emits more than 50% of the sound energy at this second frequency. The first point in time and the second point in time are spaced apart from one another in time and the first frequency is different from the second frequency.

Conversely, if the ultrasonic transducers are in reception mode, a first of the ultrasonic transducers ( US1 ) receives more than 50% of the reception amplitude at a first frequency and a second receives the ultrasonic transducer ( US2 ) less than 50% of the reception amplitude at this first frequency receives while at a second point in time during the reception of the reflected ultrasonic burst the first of the ultrasonic transducers ( US1 ) receives less than 50% of the reception amplitude at a second frequency and the second receives the ultrasonic transducer ( US2 ) receives more than 50% of the reception amplitude at this second frequency. The first point in time and the second point in time are spaced apart from one another in time and the first frequency is different from the second frequency.

This enables the transmission of ultrasonic bursts with more complex coding and with a larger frequency bandwidth, which enables a significantly better increase in the signal-to-noise ratio and thus the range. It is also possible to acquire better-resolved reflection signals from the ultrasonic bursts.

Figure 6b

In the 6b is the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) larger than the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ).

In addition, the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) greater than the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ).

Furthermore, the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) greater than half of the sum of the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) and the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 )

In the 6b is also the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) greater than the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ).

In addition, the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) greater than the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

Furthermore, the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ) greater than half of the sum of the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

In the example of the 6b is also the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) roughly equal to the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ).

In the example of the 6b is the frequency spacing ( Δf ₁₂ ) between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) roughly equal to the frequency spacing ( Δf ₂₃ ) between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 ).

When choosing the parameters of the ultrasonic transducer ( US1 , US2 , US3 ) according to the 6b more complicated signals can also be sent out. A continuous frequency sweep (chirp) is no longer possible, however, as there are considerable drops in amplitude when the common excitation frequency ( f _A ) the ultrasonic transducer (US, US2 , US3 ) in a frequency range between the amplitude spectra, here the three exemplary spectral ultrasonic burst amplitudes ( A1 , A2 , A3 ) of the exemplary three ultrasonic transducers ( US1 , US2 , US3 ), lies. The corresponding drops in amplitude of the 6a are considerably lower.

1. a) Im ersten Betriebsmodus werden alle Ultraschall-Transducer (US1, US2, US3) mit dem gleichen Ansteuersignal (AS) und damit mit der gleichen Ansteuermomentanfrequenz (f_A ) und phasensynchron angesteuert. Liegt die gemeinsame Ansteuermomentanfrequenz (f_A ) innerhalb der Gesamtfrequenzbandbreite (Δf_g ) des Ultraschallsensorsystems (USS), so schwingt mindestens einer der Ultraschallsender (US1, US2, US3) an.
2. b) Im zweiten Betriebsmodus wird zumindest einer der Ultraschall-Transducer (US1, US2, US3) mit einem anderen Ansteuersignal (AS1, AS2, AS3) und damit typischerweise nicht mehr mit der gleichen Ansteuermomentanfrequenz (f_A ), sondern mit einer anderen Ansteuermomentanfrequenz (f_A1 , f_A2 , f_A3 ) und nicht phasensynchron angesteuert.

Basically, two basic operating modes are possible for such an ultrasonic sensor system:

1. a) In the first operating mode, all ultrasonic transducers ( US1 , US2 , US3 ) with the same control signal ( AS ) and thus with the same control instantaneous frequency ( f _A ) and controlled phase-synchronously. Is the common control instantaneous frequency ( f _A ) within the total frequency bandwidth ( Δf _g ) of the ultrasonic sensor system ( USS ), at least one of the ultrasonic transmitters vibrates ( US1 , US2 , US3 ) at.
2. b) In the second operating mode, at least one of the ultrasonic transducers ( US1 , US2 , US3 ) with another control signal ( AS1 , AS2 , AS3 ) and thus typically no longer with the same control instantaneous frequency ( f _A ), but with a different control instantaneous frequency ( f _A1 , f _A2 , f _A3 ) and not controlled phase-synchronously.

Figures 7 to 10

the 7th until 10 basically show possible types of a frequency sweep. With a frequency sweep, one or more ultrasonic transducers of the ultrasonic transducer ( US1 , US2 , US2 ) with a control signal ( AS ) at which the instantaneous control frequency ( f _A ) is a function of time and changes during the emission of an ultrasonic burst ( UB ) changes through this ultrasonic transducer. In the examples of the 7th until 10 are various possible ultrasonic sweeps with a non-linear course of the ultrasonic burst instantaneous frequency ( f _m ) shown. The ultrasonic burst instantaneous frequency ( f _m ) is with the control instantaneous frequency ( f _A ) of the control signal ( AS ) the ultrasonic transducer ( US1 , US2 , US3 ) directly linked and typically follows it. In the examples of the 7th until 10 For example, initially only a first ultrasonic transducer ( US1 ) the ultrasonic transducer ( US1 , US2 , US3 ) for the emission of the ultrasonic burst ( UB ) used.

7b represents the course of the first spectral ultrasonic burst amplitude ( A1 ) of the first ultrasonic transducer ( US1 ) as a function of the instantaneous control frequency ( f _A ) in the vertical direction corresponding to 7a represent.

7a represents the first frequency curve ( SF1 ) the instantaneous ultrasonic burst frequency ( f _m ) a first ultrasonic part of the control signal to generate an ultrasonic burst ( UB ) using the first ultrasonic transducer ( US1 ). The first ultrasonic transducer ( US1 ) has a first upper half-maximum amplitude frequency ( f _1o ) and a first lower half-maximum amplitude frequency ( f _1u ) on. At a first transmission start time ( t _1s ) begins in the example of 7a the first ultrasonic transducer ( US1 ) with an instantaneous ultrasonic burst frequency ( f _m ) corresponding to a first start frequency ( f _1s ) and emit sound. For this purpose, the first ultrasonic transmitter ( US1 ) with a control signal ( AS ) with a corresponding momentary first start control frequency [ f _A1s ] controlled. At a first half-frequency time ( t _1/50% ) the first ultrasonic transducer sends ( US1 ) with a first half frequency ( f _1/50% ). For this purpose, the first ultrasonic transducer ( US1 ) with a control signal with a corresponding momentary first half-frequency control frequency [ f _{A1 / 50%} ] controlled. At a first sending end time ( t _1e ) stops in the example 7a the first ultrasonic transducer ( US1 ) the transmission process with a first end frequency ( f _1e ). For this purpose, at this first transmission end time ( t _1e ) the first ultrasonic transmitter ( US1 ) with a control signal with a corresponding momentary first final control frequency [ f _A1e ] controlled.

The first half-frequency control frequency [f _{A1 / 50%} ] is calculated in the sense of this document as follows: $${ƒ}_{\text{A1 / 50\%}}=\frac{{\mathrm{<figure-callout\; id="1s"\; label="ƒ"\; filenames="DE102020008034A1\_0011.png,DE102020008034A1\_0012.png"\; state="\{\{state\}\}">ƒ</figure-callout>}}_{1\text{s}}-{\mathrm{<figure-callout\; id="1e"\; label="ƒ"\; filenames="DE102020008034A1\_0012.png,DE102020008034A1\_0013.png"\; state="\{\{state\}\}">ƒ</figure-callout>}}_{1\text{<figure-callout id="2" label="e" filenames="DE102020008034A1\_0006.png,DE102020008034A1\_0025.png" state="{{state}}">e</figure-callout>}}}{2}+{\mathrm{<figure-callout\; id="1e"\; label="ƒ"\; filenames="DE102020008034A1\_0012.png,DE102020008034A1\_0013.png"\; state="\{\{state\}\}">ƒ</figure-callout>}}_{1\text{e}}$$

The first starting frequency ( f _1s ) naturally lies between the first upper half-maximum amplitude frequency ( f _1o ) and the first lower half-maximum amplitude frequency ( f _1u ).

The first half frequency ( f _1/50% ) is also between the first upper half-maximum amplitude frequency ( f _1o ) and the first lower half-maximum amplitude frequency ( f _1u ).

The first end frequency ( f _1e ) is also between the first upper half-maximum amplitude frequency ( f _1o ) and the first lower half-maximum amplitude frequency ( f _1u ).

The ultrasonic burst duration ( bd ) results in the example of 7th as the time difference between the first transmission end time ( t _1e ) minus the first transmission start time ( t _1s ). $$\text{bd}={\text{<figure-callout id="1e" label="t" filenames="DE102020008034A1\_0012.png,DE102020008034A1\_0013.png" state="{{state}}">t</figure-callout>}}_{1\text{e}}-{\text{<figure-callout id="1s" label="t" filenames="DE102020008034A1\_0011.png,DE102020008034A1\_0012.png" state="{{state}}">t</figure-callout>}}_{1\text{s}}$$

The half-frequency time ( t _1/50% ), to which the control signal of the first ultrasonic transducer ( US1 ) the half-frequency control frequency [ f _{A1 / 50%} ] or to which the transmission frequency of the sound radiation of the first ultrasonic transducer ( US1 ) the first half frequency ( f _1/50% ) divides the burst duration ( bd ) into a first temporal burst phase ( t _1a ) and an immediately following second temporal burst phase ( t _1b ). According to the invention it is proposed that the first burst phase ( t _1a ) significantly different in length compared to the second burst phase ( t _1b ) is designed. This increases the burst duration ( bd ) in two burst phases that are not equally long in time ( t _1a , t _1b ) divided. It is also proposed that the frequency curve of the instantaneous ultrasonic burst frequency ( f _m ) is monotonous, preferably even strictly monotonous, either decreasing or increasing. The start and end phase of the sound emission for switching the first ultrasonic transducer on and off as an example ( US1 ) is not taken into account here for the sake of simplicity in this monotonicity condition, since naturally the switch-on process is always increasing (increasing from 0 Hz) and the switch-off process is always decreasing (decreasing to 0 Hz). In the example of the 7a is the frequency curve ( SF1 ) the instantaneous ultrasonic burst frequency ( f _m ) of a first ultrasonic partial burst, for example, strictly monotonically falling and the first temporal burst phase ( t _1a ) significantly shorter in time than the second temporal burst phase ( t _1b ).

Figure 8

8b equals to 7b . Reference is made to the corresponding description.

8a equals to 7a with the difference that the frequency curve ( SF1 ) the instantaneous ultrasonic burst frequency ( f _m ) of a first partial ultrasonic burst within an ultrasonic burst ( UB ) is, for example, strictly monotonically increasing and the first temporal burst phase ( t _1a ) significantly shorter in time than the second temporal burst phase ( t _1b ) is.

Figure 9

9b equals to 7b . Reference is made to the corresponding description.

9a equals to 7a with the difference that the frequency curve ( SF1 ) the instantaneous ultrasonic burst frequency ( f _m ) a first Ultrasonic partial bursts within an ultrasonic burst ( UB ) is, for example, strictly monotonically increasing and the first temporal burst phase ( t _1a ) significantly longer than the second burst phase ( t _1b ) is.

Figure 10

10b equals to 7b . Reference is made to the corresponding description.

10a equals to 7a with the difference that the frequency curve ( SF1 ) the instantaneous ultrasonic burst frequency ( f _m ) of a first partial ultrasonic burst within an ultrasonic burst ( UB ) is, for example, strictly monotonically decreasing and the first temporal burst phase ( t _1a ) significantly longer than the second burst phase ( t _1b ) is.

Figure 11

11 shows an exemplary arrangement consisting of a first ultrasonic transducer ( US1 ) and a second ultrasonic transducer ( US2 ) and a third ultrasonic transducer ( US3 ). In the example of the 11 are the ultrasonic transducers ( US1 , US2 , US3 ) arranged in an isosceles triangle, the edge lengths of which are less than twice the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) is. In the example of the 11 the sound-emitting surfaces are exemplarily circular and for all three ultrasonic transducers ( US1 , US2 , US3 ) selected to be the same size as an example. The first ultrasonic transducer ( US1 ) transmits, when it transmits, with a first instantaneous ultrasonic burst frequency ( f _1m ). The second ultrasonic transducer ( US2 ) transmits, when it transmits, at a second instantaneous ultrasonic burst frequency ( f _2m ). The third ultrasonic transducer ( US3 ) sends, when it sends, at a third instantaneous ultrasonic burst frequency ( f _3m ).

The ultrasonic transducers are preferred ( US1 , US2 , US3 ) arranged in an isosceles triangle, the edge lengths of which are less than ten times the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) and / or smaller than five times the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) and / or smaller than three times the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) and / or better smaller than twice the diameter of the sound-emitting surfaces of the ultrasonic transducers ( US1 , US2 , US3 ) is.

Figure 12

12th equals to 7th with the difference that now a frequency sweep with the help of three ultrasonic sensors ( US1 , US2 , US3 ) is produced.

In the example of the 12th should all three ultrasonic transducers ( US1 , US2 , US3 ) with the same control signal with the same current control frequency ( f _A ) and therefore with the same instantaneous ultrasonic burst frequency ( f _1m , f _2m , f _3m ) Radiate sound. To this extent send in the example of 12th in contrast to 11 all three exemplary ultrasonic transducers ( US1 , US2 , US3 ) with a respective instantaneous ultrasonic burst frequency ( f _1m , f _2m , f _3m ) according to the current control frequency ( f _A ) or not or only negligible if the current control frequency ( f _A ) just outside their respective bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) of the respective ultrasonic transducer ( US1 , US2 , US3 ) lies.

The first ultrasonic transducer ( US1 ) has a first spectral ultrasonic burst amplitude ( A1 ) of the first ultrasonic transducer ( US1 ) on.

The second ultrasonic transducer ( US2 ) has a second spectral ultrasonic burst amplitude ( A2 ) of the second ultrasonic transducer ( US2 ) on.

The third ultrasonic transducer ( US3 ) has a third spectral ultrasonic burst amplitude ( A3 ) of the third ultrasonic transducer ( US3 ) on.

These spectral ultrasonic burst amplitudes ( A1 , A2 , A3 ) are intended here to exemplify the situation of the exemplary 6a correspond. On the associated description of the 6a is expressly referred to here.

In contrast to the emission of the ultrasonic burst ( UB ) according to the 7a ultrasonic burst instantaneous frequencies ( f _m ) that are outside the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) lie. Ie the frequency bandwidth of the in 12th emitted ultrasonic bursts ( UB ) is considerably wider than the frequency bandwidth of the in 7a emitted ultrasonic bursts ( UB ).

It is important here that the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) with the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) overlaps and that the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) with the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ) overlaps.

This now makes it possible for the first frequency curve ( SF1 ) the instantaneous ultrasonic burst frequency ( f _m ) within the ultrasonic burst ( UB ) when transmitting by means of the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) and the third ultrasonic transducer ( US3 ) any curve within the range created by the coupling of the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) and the third ultrasonic transducer ( US3 ) increased overall frequency bandwidth ( Δf _g ) of the ultrasonic sensor system ( USS ) follows. To that extent is the 12th only one particularly preferred course of the many courses that have become possible.

At a third transmission start time ( t _3s ) begins in the example of 12th the third ultrasonic transducer ( US3 ) with the emission of a partial ultrasonic burst with a third start frequency ( f _3s ), which corresponds to a third excitation start frequency [ f _A3s ] for the frequency of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 12th corresponds to jointly controlling excitation signal. The third ultrasonic transducer ( US3 ) then emits the ultrasonic burst with an ultrasonic burst instantaneous frequency ( f _m ), which at this transmission start time ( t _3s ) the third start frequency ( f _3s ) is equivalent to. The third starting frequency ( f _3s ) is necessarily within the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ). In the example of the 12th is the third starting frequency ( f _3s ) outside the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and outside the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ). For the duration of a third single mode time ( smt ₃ ) so only the third ultrasonic transducer sends ( US3 ). During this period of a third single-mode period ( smt ₃ ) is a significant excitation of the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) with the current excitation frequency ( f _A ) by means of the control signal ( AS ) not possible.

The control device ( AV ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 12th now the current control frequency ( f _A ) within the third single mode time ( smt ₃ ) continuously. At a second transmission start time ( t _2s ) begins in the example of 12th the second ultrasonic transducer ( US2 ) also in a fixed phase relationship to the emission of the third ultrasonic transducer ( US3 ) with the emission of an ultrasonic signal at a second start frequency ( f _2s ), which corresponds to a second excitation start frequency [ f _A2s ] for the frequency of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 12th corresponds to jointly controlling excitation signal. The third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) start broadcasting from this second start time ( t _2s ) phase-synchronously with the same instantaneous ultrasonic burst frequency ( f _m ) in this example. This starts a first dual mode time ( dmt ₂₃ ), in which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) Emit sound at the same time.

The control device ( AV ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 12th now the current control frequency ( f _A ) within the dual mode time ( dmt ₂₃ ), in which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) Radiate sound, continue to emit continuously. This also reduces the instantaneous ultrasonic burst frequency ( f _m ) with which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) Sound continues to radiate. At a third transmission end time ( t _3e ) stops in the example 12th the third ultrasonic transducer ( US3 ) the emission of its ultrasonic signal at a third end frequency ( f _3e ), which corresponds to a third final excitation frequency [ f _A3e ] for the frequency of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 12th jointly controlling excitation signal ( AS ) is equivalent to. In this example the 12th a second single mode time ( smt ₂ ) in which only the second ultrasonic transducer ( US2 ) Emits sound.

The control device ( AV ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 12th now the current control frequency ( f _A ) within the second single mode time ( smt ₂ ) continues to decrease continuously. This also reduces the instantaneous ultrasonic burst frequency ( f _m ) with which the second ultrasonic transducer ( US2 ) Sound continues to radiate. At a first transmission start time ( t _1s ) begins in the example of 12th the first ultrasonic transducer ( US1 ) also in a fixed phase relationship to the emission of the second ultrasonic transducer ( US2 ) with the emission of an ultrasonic signal at a first start frequency ( f _1s ), which has a first excitation start frequency [ f _A1s ] for the frequency of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 12th corresponds to jointly controlling excitation signal. The first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) start broadcasting from this first start time ( t _1s ) phase-synchronously with the same instantaneous ultrasonic burst frequency ( f _m ) in this example. This starts a second dual mode time ( dmt ₁₂ ), in which the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) Radiate sound.

The control device for the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 12th now the current control frequency ( f _A ) within the dual mode time ( dmt ₁₂ ), in which the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) Radiate sound, continue to emit continuously. This also reduces the instantaneous ultrasonic burst frequency ( f _m ), with which the second ultrasonic transducer ( US2 ) and the first ultrasonic transducer ( US1 ) Sound continues to radiate.

At a second sending end time ( t _2e ) stops in the example 12th the second ultrasonic transducer ( US2 ) the emission of an ultrasonic signal at a second end frequency ( f _2e ), which corresponds to a second final excitation frequency [ f _A2e ] for the frequency of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 12th corresponds to jointly controlling excitation signal. This means that at this point in time the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) with an instantaneous ultrasonic burst frequency ( f _m ) Emit sound that corresponds to this second wide end frequency ( f _2e ) is equivalent to. In this example the 12th a first single-mode period ( smt ₁ ) in which only the first ultrasonic transducer ( US1 ) Emits sound.

The control device for the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 12th now the current control frequency ( f _A ) within the first single mode time ( smt ₁ ), in which only the first ultrasonic transducer ( US1 ) Sound emits, continues to emit continuously. This also reduces the instantaneous ultrasonic burst frequency ( f _m ) with which the remaining first ultrasonic transducer ( US1 ) nor sound continues to radiate. At a first sending end time ( t _1e ) stops in the example 12th the first ultrasonic transducer ( US1 ) the emission of an ultrasonic signal at a first end frequency ( f _1e ), which corresponds to a first final excitation frequency [ f _A1e ] for the frequency of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 12th corresponds to jointly controlling excitation signal. This means that at this point in time the first ultrasonic transducer ( US1 ) with an instantaneous ultrasonic burst frequency ( f _m ) Emits sound that corresponds to this second wide end frequency ( f _2e ) is equivalent to. This ends the in this example 12th the emission of the ultrasonic burst (US) and thus the burst duration ( bd ). The sound radiation then ends altogether and the ultrasonic burst ( UB ) is finished.

Figure 13

13th shows, in a simplified and schematic manner, an exemplary system for generating the exemplary frequency response of FIG 12th . For example, an ultrasonic sensor system ( USS ) corresponding 11 used. A control device ( AV ) can be part of the ultrasonic sensor system ( USS ) or outside of the ultrasonic sensor system ( USS ) be arranged.

The control device ( AV ) generates one or more control signals ( AS ) that here, for example, a plurality of ultrasonic transducers ( US1 , US2 , US3 ) to be led. Thus the ultrasonic transducers ( US1 , US2 , US3 ) the majority of ultrasound transducers ( US1 , US2 , US3 ) with the same control frequency ( f _A ) of the control signal ( AS ) excited to vibrate. The ultrasonic transducers ( US1 , US2 , US3 ) however only start to oscillate if the current control frequency ( f _A ) of the control signal ( AS ) in their respective bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) lies.

Figure 14

14th corresponds in essential parts to 12th . Now, however, the excitation signal includes ( AS ) at times more than one excitation frequency ( f _A ). For example, the control signal ( AS ) a first excitation frequency ( f _A1 ) a first excitation signal component and a second excitation frequency ( f _A2 ) a second excitation signal component and a third excitation frequency ( f _A3 ) include a third excitation signal component. The first excitation signal component and the second excitation signal component and the third excitation signal component are then preferably added to the actual excitation signal ( AS ) superimposed.

In the example of the 14th should initially in a first phase of the exemplary ultrasonic burst ( UB ) for example all three ultrasonic transducers ( US1 , US2 , US3 ) with the same control signal ( AS ) with the same first control instantaneous frequency ( f _A1 ) can be controlled. To this extent send in the example of 14th in contrast to 11 all three exemplary ultrasonic transducers ( US1 , US2 , US3 ) again with the frequencies corresponding to the control instantaneous frequencies ( f _A1 , f _A2 ) or not or only negligible if the control instantaneous frequencies ( f _A1 , f _A2 ) just outside their respective bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) lie.

The first ultrasonic transducer ( US1 ) shows as in 12th a first spectral ultrasonic burst amplitude ( A1 ) of the first ultrasonic transducer ( US1 ) on.

The second ultrasonic transducer ( US2 ) shows as in 12th a second spectral ultrasonic burst amplitude ( A2 ) of the second ultrasonic transducer ( US2 ) on.

The third ultrasonic transducer ( US3 ) shows as in 12th a third spectral ultrasonic burst amplitude ( A3 ) of the third ultrasonic transducer ( US3 ) on.

These spectral ultrasonic burst amplitudes ( A1 , A2 , A3 ) should here as in 12th exemplary of the situation of exemplary 6a correspond. on the corresponding description of the 6a is expressly referred to here.

In contrast to the emission of the ultrasonic burst ( UB ) according to the 12th are now in the 14th temporarily more than two instantaneous ultrasonic burst frequencies within the emitted ultrasonic burst, emitted. Ie the frequency bandwidth of the in 14th emitted ultrasonic bursts ( UB ) is also related to individual transmission times during the burst duration ( bd ) of the ultrasonic burst ( UB ) at least at times considerably wider than the current frequency bandwidth of the in 12th emitted ultrasonic bursts ( UB ).

It is also important here that the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) with the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) overlaps and that the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) with the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ) overlaps.

This now makes it possible for the first frequency curve ( SF1 ) the first excitation frequency ( f _A1 ) a first signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) using the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) and the third ultrasonic transducer ( US3 ) as the first ultrasonic partial burst within the ultrasonic burst ( UB ) and thus the first frequency curve ( SF1 ) the ultrasonic _{instantaneous} frequency (f m1) follows an arbitrary curve within the overall bandwidth increased in this way. To that extent is the 14th only one particularly preferred course of the many courses that have become possible.

Furthermore, it is also possible that in addition to the first frequency curve ( SF1 ) a second frequency curve ( SF2 ) a second ultrasonic _{burst instantaneous} frequency (f m2) of a second ultrasonic partial burst within an ultrasonic burst ( UB ) and possibly a third frequency curve (not shown) ( SF3 ) a third ultrasonic _{burst instantaneous} frequency (f m3) of a third ultrasonic partial burst within the ultrasonic burst ( UB ) any second curve or third curve, not shown, within the overall bandwidth increased in this way, regardless of the first frequency curve ( SF1 ) follow the first instantaneous ultrasonic frequency (f _m1 ). To that extent is the 14th only one particularly preferred course of many courses and frequency course combinations that have become possible as possible. Theoretically, n frequency curves, with n as a whole positive number, n ultrasonic burst instantaneous frequencies of ultrasonic partial bursts within the ultrasonic burst ( UB ) n arbitrary curves within the thus increased total bandwidth independent of the first frequency curve ( SF1 ) the first instantaneous ultrasonic frequency (f _m1 ) ( f _A1 ) follow

At a third transmission start time ( t _3s ) begins in the example of 14th the third ultrasonic transducer ( US3 ) with the transmission of an ultrasonic signal with a third start frequency ( f _3s ) as the first instantaneous ultrasonic frequency (f _m1 ), that of a third excitation start frequency [ f _A3s ] for the first excitation frequency ( f _A1 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. The third starting frequency ( f _3s ) is within the third range ( Δf ₃ ) of the third ultrasonic transducer ( US3 ). In the example of the 14th is the third starting frequency ( f _3s ) outside the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and outside the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ). For the duration of a third single mode time ( smt ₃ ) so only the third ultrasonic transducer sends ( US3 ) with the first instantaneous ultrasonic frequency (f _m1 ). During this period of a third single-mode period ( smt ₃ ) is a significant excitation of the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) with the current first excitation frequency ( f _A1 ) not possible.

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 13th now the current first control frequency ( f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the third single-mode time ( smt ₃ ) continuously. At a second transmission start time ( t _2s ) begins in the example of 14th the second ultrasonic transducer ( US2 ) also in a fixed phase relationship to the emission of the third ultrasonic transducer ( US3 ) with the emission of an ultrasonic signal with a first ultrasonic _{instantaneous} frequency (f m1) at a second starting frequency ( f _2s ), which corresponds to a second excitation start frequency [ f _A2s ] for the current first control frequency ( f _A1 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. This starts a dual mode time ( dmt ₂₃ ), in which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) Radiate sound with the first ultrasonic _{instantaneous} frequency (f m1).

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the first current control frequency ( f _A1 ) within the dual mode time ( dmt ₂₃ ), in which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) Sound with the first ultrasonic _{instantaneous} frequency (f m1) radiate, continue to radiate continuously. At a third transmission end time ( t _3e ) stops in the example 14th the third ultrasonic transducer ( US3 ) the emission of an ultrasonic _{signal with the first ultrasonic instantaneous frequency (f m1} ) at a third end frequency ( f _3e ), which corresponds to a third final excitation frequency [ f _A3e ] for the current first control frequency ( f _A1 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. In this example the 14th a second single mode time ( smt ₂ ) in which only the second ultrasonic transducer ( US2 ) Emits sound with the first ultrasonic _{instantaneous} frequency (f m1).

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the current first control frequency ( f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the second single-mode time ( smt ₂ ) continues to decrease continuously. At a first transmission start time ( t _1s ) begins in the example of 14th the first ultrasonic transducer ( US1 ) also in a fixed phase relationship to the emission of the second ultrasonic transducer ( US2 ) with the emission of an ultrasonic signal of the first ultrasonic _{instantaneous} frequency (f m1) at a first starting frequency ( f _1s ), which has a first excitation start frequency [ f _A1s ] for the control frequency ( f _A1 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. This starts a dual mode time ( dmt ₁₂ ), in which the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) emit sound with the first ultrasonic _{instantaneous frequency (f m1).}

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the current first control frequency ( f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the dual-mode time ( dmt ₁₂ ), in which the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) Emit sound with the first ultrasonic _{instantaneous} frequency (f m1), continue to emit continuously. At a second sending end time ( t _2e ) stops in the example 14th the second ultrasonic transducer ( US2 ) the emission of an ultrasonic _{signal with the first ultrasonic instantaneous frequency (f m1} ) at a second end frequency ( f _2e ), which corresponds to a second final excitation frequency [ f _A2e ] for the first control frequency ( f _A1 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. In this example the 14th a first single-mode period ( smt ₁ ) in which only the first ultrasonic transducer ( US1 ) Emits sound with the first ultrasonic _{instantaneous} frequency (f m1).

The control device for the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th then the current first control frequency ( f _A1 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) within the first single-mode time ( smt ₁ ), in which only the first ultrasonic transducer ( US1 ) Emits sound with the first ultrasonic _{instantaneous} frequency (f m1), continues to emit continuously. At a first sending end time ( t _1e ) stops in the example 14th the first ultrasonic transducer ( US1 ) the emission of the proportional ultrasonic _{signal with the first ultrasonic instantaneous frequency (f m1} ) at a first end frequency ( f _1e ), which corresponds to a first final excitation frequency [ f _A1e ] for the current first control frequency ( f _A1 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th corresponds to jointly controlling excitation signal. This ends the in this example 12th the emission of the ultrasonic burst (US) and thus the burst duration ( bd ). The sound radiation then ends.

In contrast to 12th is now at least for a time segment of the burst duration ( bd ) parallel to the first partial ultrasound burst with the first frequency curve ( SF1 ) the first ultrasonic _{instantaneous} frequency (f m1) a second ultrasonic burst part with a second frequency curve ( SF2 ) the second instantaneous ultrasonic frequency (f _m2 ) preferably by summation in the control signal ( AS ) superimposed. The control signal ( AS ) thus typically has a first instantaneous ultrasonic frequency (f _m1 ) as a first frequency component and a second instantaneous ultrasonic frequency (f _m2 ) as frequency components in the time segments of this superposition.

In the example of the 14th is exemplified in the first single-mode period ( smt ₁ ) by generating this second frequency curve ( SF2 ) the second ultrasonic _{burst instantaneous} frequency (f m2) of a second ultrasonic partial burst within an ultrasonic burst ( UB ) on the structure of the ultrasonic burst of the 12th deviated.

At a further third transmission start time (t _3sb ), in the example, the 14th the third ultrasonic transducer ( US3 ) with the transmission of an additional ultrasonic partial burst with the third start frequency ( f _3s ) as the second instantaneous ultrasonic frequency (f _m2 ), which is here again the third excitation start frequency [ f _A3s ] for the second excitation frequency ( f _A2 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. From this point in time, the third transmission start point in time (t _3sb ), the control signal ( AS ) So not only a first ultrasonic partial burst with a first ultrasonic _{instantaneous} frequency (f m1), but also a second ultrasonic partial burst with a second ultrasonic instantaneous frequency (f _m2 ). The third starting frequency ( f _3s ) is typically within the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ). It is assumed here as unchanged by way of example. In the example of the 14th is the third starting frequency ( f _3s ) outside the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) and outside the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ). Send for the duration of a third dual-mode time (dmt ₁₃ ) in the example of 14th the third ultrasonic transducer ( US3 ) with a second ultrasonic instantaneous frequency (f _m2 ) and the first ultrasonic transducer ( US1 ) with a first instantaneous ultrasonic frequency (f _m1 ) each from a sound signal.

Since the first momentary control frequency ( f _A1 ) in this third dual-mode time (dmt ₁₃ ) below the third lower half-maximum amplitude frequency ( f _3u ), the third ultrasonic transducer vibrates ( US3 ) not with the first current control frequency ( f _A1 ) at.

Since the first momentary control frequency ( f _A1 ) in this third dual-mode time (dmt ₁₃ ) also below the second lower half-maximum amplitude frequency ( f _2u ), the second ultrasonic transducer also vibrates ( US2 ) not with the first current control frequency ( f _A1 ) at.

Since the second current control frequency ( f _A2 ) in this third dual-mode time (dmt ₁₃ ) above the second upper half-maximum amplitude frequency ( f _2o ), the second ultrasonic transducer vibrates ( US2 ) not with the second current control frequency ( f _A2 ) at.

Since the second current control frequency ( f _A2 ) in this third dual-mode time (dmt ₁₃ ) above the first upper half-maximum amplitude frequency ( f _1o ) lies, the first ultrasonic transducer vibrates ( US1 ) not with the second current control frequency ( f _A2 ) at.

During this period of a third dual-mode time (dmt ₁₃ ), a significant excitation of the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) with the current second excitation frequency ( f _A2 ) not possible.

During this period, that of a third dual-mode time (dmt ₁₃ ), a significant excitation of the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) with the current first excitation frequency ( f _A1 ) not possible.

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the current first control frequency ( f _A1 ) and thus the first _{instantaneous ultrasonic frequency (f m1} ) and the instantaneous second control frequency ( f _A2 ) and thus the second _{instantaneous ultrasonic frequency (f m2} ) together continuously decrease within the third dual-mode time (dmt _13). At a further, second transmission start time (t _2sb ), the begins in the example 14th the second ultrasonic transducer ( US2 ) also in a fixed phase relationship to the emission of the third ultrasonic transducer ( US3 ) with the emission of an ultrasonic signal with the second ultrasonic instantaneous frequency (f _m2 ) at a second starting frequency ( f _2s ), which corresponds to a second excitation start frequency [ f _A2s ] for the current second control frequency ( f _A2 ) of the second signal component of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. This starts a tri-mode time (tmt ₁₂₃ ) in which the third ultrasonic transducer ( US3 ) with the second ultrasonic instantaneous frequency (f _m2 ) and the second ultrasonic transducer ( US2 ) with the second ultrasonic instantaneous frequency (f _m2 ) and the first ultrasonic transducer ( US1 ) emit sound with the first ultrasonic _{instantaneous frequency (f m1).}

Since the first momentary control frequency ( f _A1 ) in this third dual-mode time (dmt ₁₃ ) below the third lower half-maximum amplitude frequency ( f _3u ), the third ultrasonic transducer vibrates ( US3 ) not with the first current control frequency ( f _A1 ) at.

Since the first momentary control frequency ( f _A1 ) in this third dual-mode time (dmt ₁₃ ) also below the second lower half-maximum amplitude frequency ( f _2u ), the second ultrasonic transducer also vibrates ( US2 ) not with the first current control frequency ( f _A1 ) at.

Since the second current control frequency ( f _A2 ) in this third dual-mode time (dmt ₁₃ ) now below the second upper half-maximum amplitude frequency ( f _2o ) and above the second lower half-maximum amplitude frequency ( f _2u ), the second ultrasonic transducer vibrates ( US2 ) now with the second current control frequency ( f _A2 ) and emits sound with the second ultrasonic instantaneous frequency (f _m2 ).

Since the second current control frequency ( f _A2 ) in this third dual-mode time (dmt ₁₃ ) above the first upper half-maximum amplitude frequency ( f _1o ) lies, the first ultrasonic transducer vibrates ( US1 ) not with the second current control frequency ( f _A2 ) and emits sound of the first ultrasonic _{instantaneous} frequency (f m1).

During this period of time a third tri-mode time (tmt ₁₂₃ ) is a significant stimulation of the first ultrasound transducer ( US1 ) with the current second excitation frequency ( f _A2 ) not possible.

During this period of a third tri-mode time (tMt ₁₂₃ ), a significant excitation of the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) with the current first excitation frequency ( f _A1 ) not possible.

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the first current control frequency ( f _A1 ) and the second current control frequency ( f _A2 ) and thus the first ultrasonic _{instantaneous frequency (f m1} ) and the second ultrasonic _{instantaneous frequency (f m2} ) within the tri-mode time (tmt ₁₂₃ ) in which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) and the first ultrasonic transducer ( US1 ) Radiate sound, continue to emit continuously. At a further third _transmission end time (t 3eb), the stops in the example 14th the third ultrasonic transducer ( US3 ) the transmission of the ultrasonic _{signal with the second ultrasonic instantaneous frequency (f m2} ) at a third end frequency ( f _3e ), which corresponds to a third final excitation frequency [ f _A3e ] for the current second control frequency ( f _A2 ) of the signal component of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. In this example the 14th a fourth dual-mode time (dmt _12b ) in which only the second ultrasonic transducer ( US2 ) with the second ultrasonic instantaneous frequency (f _m2 ) and the first ultrasonic transducer ( US1 ) emit sound with the first ultrasonic _{instantaneous frequency (f m1).}

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the current first control frequency ( f _A1 ) and the current second control frequency ( f _A2 ) and thus the first instantaneous ultrasonic frequency (f _m1 ) and the second _{instantaneous ultrasonic frequency (f m2} ) continue to decrease continuously within the fourth dual-mode time (dmt _12b). At a first transmission start time ( t _1s ) begins in the example of 14th the first ultrasonic transducer ( US1 ) also in a fixed phase relationship to the emission of the second ultrasonic transducer ( US2 ) with the emission of a second partial ultrasonic burst of the ultrasonic signal at a first start frequency ( f _1s ), which has a first excitation start frequency [ f _A1s ] for the second control frequency ( f _A2 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. The special thing about this is that the first ultrasonic transducer ( US1 ) for this purpose must vibrate with two frequencies, with the first ultrasonic _{instantaneous} frequency (f m1) and with the second ultrasonic instantaneous frequency (f _m2). This is not always possible. As a rule, the current control frequencies ( f _A1 , f _A2 ) are so close together that the oscillation of the first ultrasonic transducer ( US1 ) comes.

This starts a second tri-mode time ( dmt ₁₂ ), in which the first ultrasonic transducer ( US1 ) with the first ultrasonic _{instantaneous} frequency (f m1) and simultaneously with the second ultrasonic instantaneous frequency (f _m2 ) emits sound and the second ultrasonic transducer ( US2 ) emits sound at the second instantaneous ultrasonic frequency (f _m2 ), whereby the first ultrasonic transducer _{oscillates at two instantaneous ultrasonic frequencies (f m1} and f _m2 ).

The control device ( AS ) of the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th now the current first control frequency ( f _A1 ) and the current second control frequency ( f _A2 ) and thus the first ultrasonic _{instantaneous frequency (f m1} ) and the second ultrasonic _{instantaneous frequency (f m2} ) within the second tri-mode time (tmt ₁₁₂ ) in which the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) Radiate sound, continue to emit continuously. At a second sending end time ( t _2e ) stops in the example 14th the second ultrasonic transducer ( US2 ) the emission of an ultrasonic _{signal with the second ultrasonic instantaneous frequency (f m2} ) at a second end frequency ( f _2e ), which corresponds to a second final excitation frequency [ f _A2e ] for the second control frequency ( f _A1 ) of the second signal component of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. In this example the 14th a last dual-mode time (dmt _11b ) in which only the first ultrasonic transducer ( US1 ) Emits sound. The first ultrasonic transducer vibrates ( US1 ) initially with two ultrasonic _{instantaneous} frequencies (f m1, f _m2 ). In the example, the decreases towards the end 14th the frequency spacing between the first instantaneous ultrasonic frequency (f _m1 ) and the second instantaneous ultrasonic frequency (f _m2 ) until finally the two instantaneous ultrasonic frequencies (f _m1 , f _m2 ) in the example of FIG 14th are the same.

The control device for the three ultrasonic transducers ( US1 , US2 , US3 ) lowers in the example 14th thus the current first control frequency ( f _A1 ) and the current second control frequency ( f _A2 ) within the last dual-mode time (dmt _11b ), in which only the first ultrasonic transducer ( US1 ) Sound emits, continues to emit continuously. At a first sending end time ( t _1e ) stops in the example 14th the first ultrasonic transducer ( US1 ) the emission of the proportional ultrasonic signal at a first end frequency ( f _1e ), which corresponds to a first final excitation frequency [ f _A1e ] for the current first control frequency ( f _A1 ) and the current second control frequency ( f _A2 ) of the three ultrasonic transducers ( US1 , US2 , US3 ) in the example of 14th jointly controlling excitation signal ( AS ) is equivalent to. This ends the in this example 14th the emission of the ultrasonic burst (US) and thus the burst duration ( bd ). The sound radiation then ends.

Figure 15

15th shows, in a simplified and schematic manner, an exemplary system for generating the exemplary frequency response of the following 16 . For example, an ultrasonic sensor system ( USS ) corresponding 11 used.

In contrast to the system of 13th the first ultrasonic transducer ( US1 ) now via its own first control device ( AV1 ). The second ultrasonic transducer ( US2 ) now has its own second control device ( AV2 ). The third ultrasonic transducer ( US3 ) now has its own third control device ( AV3 ).

The first control device ( AV1 ) controls the first ultrasonic transducer ( US1 ) with the help of a first control signal ( AS1 ) at.

The second control device ( AV2 ) controls the second ultrasonic transducer ( US2 ) with the help of a second control signal ( AS2 ) at.

The third control device ( AV3 ) controls the third ultrasonic transducer ( US3 ) with the help of a third control signal ( AS3 ) at.

A control unit (SG) controls the first control device ( AV1 ).

The control unit (SG) controls the second control device ( AV2 ).

The control unit (SG) controls the third control device ( AV3 ).

The control devices ( AV1 , AV2 , AV3 ) synchronized via the data bus. In this case the control devices include ( AV1 , AV2 , AV3 ) preferably own time bases, for example clock generators or timers that maintain synchronization for a sufficiently long time without further synchronization signals from the control unit (SG).

Thus, the ultrasonic transducers ( US1 , US2 , US3 ) the majority of ultrasound transducers ( US1 , US2 , US3 ) with the same or different control frequencies ( f _A1 , f _A2 , f _A3 ) the control signals ( AS1 , AS2 , AS3 ) are stimulated to swing individually and independently. The ultrasonic transducers ( US1 , US2 , US3 ) however only start to oscillate if the current control frequencies ( f _A1 , f _A2 , f _A3 ) of the respective control signals ( AS1 , AS2 , AS3 ) in their respective, associated bandwidth ( Δf ₁ , Δf ₂ , Δf ₃ ) lie.

Figure 16

16 equals to 12th with the difference that now a first frequency curve ( SF1 ) the first momentary excitation frequency ( f _A1 ) a first signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) together with a second frequency curve ( SF2 ) the second instantaneous excitation frequency ( f _A2 ) a second signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) and together with a third frequency curve ( SF3 ) the third instantaneous excitation frequency ( f _A3 ) a third signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) be used. This causes the ultrasonic sensor system to emit ( USS ) at least temporarily from an ultrasonic _{signal that comprises a first ultrasonic partial burst} with a first ultrasonic instantaneous frequency (f m1) and a second ultrasonic partial burst with a second ultrasonic instantaneous frequency (f _m2 ) and a third ultrasonic _{partial burst} with a third ultrasonic instantaneous frequency (f m3) summed up overlaid.

The corresponding signal can both by means of a device accordingly 15th , as well as by means of a device accordingly 13th be generated.

Since the first frequency curve ( SF1 ) completely within the first bandwidth ( Δf ₁ ) of the first ultrasonic transducer ( US1 ) remains, it is possible to detect this part of the ultrasonic burst only with the first ultrasonic transducer ( US1 ), the first ultrasonic transducer then with a first control signal ( AS1 ) is controlled so that only the first control frequency ( f _A1 ) includes. The first ultrasonic transducer ( US1 ) then emits a first partial ultrasonic burst with the first instantaneous ultrasonic frequency (f _m1 ), which corresponds to the first control frequency ( f _A1 ) is equivalent to.

Since the second frequency curve ( SF2 ) completely within the second bandwidth ( Δf ₂ ) of the second ultrasonic transducer ( US2 ) remains, it is possible to only use the second ultrasonic transducer ( US2 ), the second ultrasonic transducer then with a second control signal ( AS2 ) is controlled so that only the second control frequency ( f _A2 ) includes. The second ultrasound Transducer ( US2 ) then emits a second partial ultrasonic burst with the second instantaneous ultrasonic frequency (f _m2 ) that corresponds to the second control frequency ( f _A2 ) is equivalent to.

Since the third frequency curve ( SF3 ) completely within the third bandwidth ( Δf ₃ ) of the third ultrasonic transducer ( US3 ) remains, it is possible to only use the third ultrasonic transducer ( US3 ), the third ultrasonic transducer then with a third control signal ( AS3 ) is controlled so that only the third control frequency ( f _A3 ) includes. The third ultrasonic transducer ( US3 ) then emits a third partial ultrasonic burst with the third instantaneous ultrasonic frequency (f _m3 ) that corresponds to the third control frequency ( f _A3 ) is equivalent to.

At a first transmission start time ( t _1s ) the first ultrasonic transducer begins ( US1 ) with the first start frequency ( f _1s ) to oscillate as the first instantaneous ultrasonic frequency (f _m1 ) and to emit its sound signal with this first instantaneous ultrasonic frequency (f _m1 ). For this purpose, a control device ( AV ) or a first control device ( AV1 ) the first ultrasonic transducer ( US1 ) with a current first control frequency ( f _A1 ), which essentially corresponds to the desired first ultrasonic _{instantaneous} frequency (f m1) of the sound radiation. In the example of the 15th lowers the control device ( AV ) or the first control device ( AV1 ) the current first control frequency ( f _A1 ) and thus the first ultrasonic _{instantaneous} frequency (f m1) of the sound radiation of the first ultrasonic transducer ( US1 ) as time goes on. At a first sending end time ( t _1e ) then the first ultrasonic transducer ends ( US1 ) the sound radiation at a first end frequency ( f _1e ) as the first instantaneous ultrasonic frequency (f _m1 ).

At a second transmission start time ( t _2s ) then the second ultrasonic transducer begins ( US2 ) with the second start frequency ( f _2s ) to oscillate as the second instantaneous ultrasonic frequency (f _m2 ) and to emit its sound signal with this second instantaneous ultrasonic frequency (f _m2 ). For this purpose, a control device ( AV ) or a second control device ( AV2 ) the second ultrasonic transducer ( US2 ) with a momentary second control frequency ( f _A2 ), which essentially corresponds to the desired second instantaneous ultrasonic frequency (f _m2). In the example of the 15th lowers the control device ( AV ) or the second control device ( AV2 ) the current second control frequency ( f _A2 ) and thus the second instantaneous ultrasonic frequency (f _m2 ) of the sound radiation of the second ultrasonic transducer ( US2 ) as time goes on. At a second sending end time ( t _2e ) then terminates the second ultrasonic transducer ( US2 ) the sound radiation at a second end frequency ( f _2e ) as the second instantaneous ultrasonic frequency (f _m2 ).

At a third transmission start time ( t _3s ) then the third ultrasonic transducer begins ( US3 ) with the third starting frequency ( f _3s To swing) as a third ultrasonic instantaneous frequency (f _m3) and to radiate its sound signal with the third ultrasonic instantaneous frequency (f _m3). For this purpose, a control device ( AV ) or a third control device ( AV3 ) the third ultrasonic transducer ( US3 ) with a current third control frequency ( f _A3 ), which essentially corresponds to the desired instantaneous oscillation frequency. In the example of the 15th lowers the control device ( AV ) or the third control device ( AV3 ) the current third control frequency ( f _A3 ) and thus the third ultrasonic _{instantaneous} frequency (f m3) of the sound radiation of the third ultrasonic transducer ( US3 ) as time goes on. At a third transmission end time ( t _3e ) then ends the third ultrasonic transducer ( US3 ) the sound radiation at a third end frequency ( f _3e ) as the third instantaneous ultrasonic frequency (f _m3 ).

In the example of the 16 is the first start time ( t _1s ) before the second start time ( t _2s ) and the third start time ( t _3s ). This results in a first single-mode time ( smt ₁ ), in which only the first ultrasonic transducer ( US1 ) Emits sound with the first ultrasonic _{instantaneous} frequency (f m1).

In the example of the 16 is the second start time ( t _2s ) after the first start time ( t _1s ) and before the third start time ( t _3s ). This results in a first dual-mode time (dmt ₁ ) in which only the first ultrasonic transducer ( US1 ) with the first ultrasonic _{instantaneous} frequency (f m1) and the second ultrasonic transducer ( US2 ) With the second ultrasonic instantaneous frequency (f _m2) different ultrasonic sound with instantaneous frequencies (f _m1, f _m2 radiate).

After the third start time ( t _3s ) then the third ultrasonic transducer also begins ( US3 _{) To} emit sound with the third ultrasonic instantaneous frequency (f m3). This results in a period beginning with the third start time ( t _3s ) and ending with the first end time ( t _1e ) a first tri-mode time (tmt) in which all three ultrasonic transducers ( US1 , US2 , US3 ) Emit sound with three different frequencies. The first ultrasonic transducer ( US1 ) emits sound with the first ultrasonic _{instantaneous} frequency (f m1). The second ultrasonic transducer ( US2 ) emits sound with the second instantaneous ultrasonic frequency (f _m2 ). The third ultrasonic transducer ( US3 ) emits sound with the third instantaneous ultrasonic frequency (f _m3 ).

In the example of the 16 is the first end time ( t _1e ) before the second end time ( t _2e ) and the third end time ( t _3e ). This results in a second dual-mode time (dmt ₂ ) in which only the second ultrasonic transducer ( US2 ) emits sound with the second ultrasonic instantaneous frequency (f _m2 ) and the third ultrasonic transducer ( US3 ) emits sound at the third instantaneous ultrasonic frequency (f _m3). The second dual mode time (dmt ₂ ) ends with the second end time ( t _2e ).

In the example of the 16 is the second end time ( t _2e ) after the first end time ( t _1e ) and before the third end time ( t _3e ). This results in a second single-mode time ( smt ₂ ), in which only the third ultrasonic transducer ( US3 ) emits sound at the third instantaneous ultrasonic frequency (f _m3). The second single-mode period ( smt ₂ ) ends with the third end time ( t _3e ). This is then also the end of the ultrasonic burst.

Figure 17

17th equals to 12th with the difference that now a first frequency curve ( SF1 ) the _{first instantaneous ultrasonic frequency (f m1} ) of a first partial ultrasonic burst corresponding to the frequency curve of the first instantaneous excitation frequency ( f _A1 ) a first signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) together with a second frequency curve ( SF2 ) the second instantaneous ultrasonic frequency (f _m2 ) of a second partial ultrasonic burst corresponding to the second instantaneous excitation frequency ( f _A2 ) a second signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) and together with a third frequency curve ( SF3 ) the third instantaneous ultrasonic frequency (f _m3 ) corresponding to the third instantaneous excitation frequency ( f _A3 ) a third signal component of the control signal ( AS ) to generate an ultrasonic burst ( UB ) be used. In contrast to the previous one 16 now all frequency curves end ( SF1 , SF2 , SF3 ) at a common end frequency (f _e ) as the respective _{instantaneous ultrasonic frequency (f m1} , f _m2 , f _m3 ) at a common end time (t _e ). Here this common end frequency (f _e ) is chosen so that it can be used by all three exemplary ultrasonic transducers ( US1 , US2 , US3 ) can be generated. Two of the frequency curves are here, for example, monotonically decreasing, one monotonically increasing.

Figure 18 & Figure 19

The sound radiation of the ultrasonic sensor system ( USS ), if the distance between the ultrasonic sensors is neglected, corresponds to ( US1 , US2 , US3 ) and the dimensions of the ultrasonic sensor system ( USS ) even a multipole expansion of a spherical spherical wave function. Ie the sound radiation lobe of an ultrasonic transducer ( US1 , US2 , US3 ) of the ultrasonic sensor system ( USS ) each has an opening angle. The sound radiation lobe of an ultrasonic sensor has a lobe axis. If the sound radiation lobe is cut perpendicular to the lobe axis in a cut surface, the intensity distribution of the sound in this cut surface is usually not distributed rotationally symmetrically around the point of penetration of the lobe axis through this cutting plane, but rather elliptically. The opening angle of the sound radiation of an ultrasonic sensor in the vertical is preferably often different from the opening angle of the sound radiation in the horizontal. In the 18th are the opening angles in the horizontal with the index H and the opening angles in the vertical with the index V. The 18a outlines the situation in supervision. the 18b outlines the situation from the side.

The sound radiation lobe of the first ultrasonic transducer ( US1 ) of the ultrasound system ( USS ) have the vertical opening angle α _V and the horizontal opening angle α _H.

The sound radiation lobe of the second ultrasonic transducer ( US2 ) of the ultrasound system ( USS ) have the vertical opening angle β _V and the horizontal opening angle β _H.

The sound radiation lobe of the third ultrasonic transducer ( US3 ) of the ultrasound system ( USS ) have the vertical opening angle γ _V and the horizontal opening angle γ _H.

In the example of the 18th are an example of the opening angles of the first ultrasonic transducer ( US1 ) designed larger than the opening angle of the second ultrasonic transducer ( US2 ) and larger than the opening angle of the third ultrasonic transducer ( US3 ).

In the example of the 18th are the opening angles of the second ultrasonic transducer ( US2 ) designed smaller than the opening angle of the first ultrasonic transducer ( US1 ) and larger than the opening angle of the third ultrasonic transducer ( US3 ).

The different opening angles can be designed, for example, by the size of the membrane compared to the sound wavelength. The resonance frequencies can be adapted through the choice of material and material thickness. The choice of the excitation frequency ( f _A1 , f _A2 , f _A3 ) of the respective ultrasonic transducer ( US1 , US2 , US3 ) changes the dimensions of the radiation lobe.

This now has the advantage that with different excitation frequencies the reflections of objects equidistant from the ultrasound system ( O1 , O2 ) (see also 19th ) differ by the spectral composition of the reflected signal. In this way, it is possible to determine the angle.

Figure 20

20th illustrates how the different types of modulation described above can now be used when approaching an important object ( O ), for example an obstacle, can be used.

In the example of the 20th the burst duration ( bd ) with the approach to the object ( O ) shortened.

The number of simultaneously transmitted frequency curves ( SF1 , SF2 , SF3 ) if the distance between the ultrasonic sensor system ( USS ) and object ( O , O1 , O2 ) increased from two to three. The number of simultaneously transmitted frequency curves ( SF1 , SF2 , SF3 ) thus changes with the approach to the object ( O ). Within an ultrasonic burst, the number of frequency curves is initially increased from 1 to 2. With closer proximity, the number of frequency curves is then increased from 1 to 3 within an ultrasonic burst.

The frequency curves are in the example of 20th all always fall strictly monotonically within an ultrasonic burst, whereby the rate of fall of the ultrasonic _{instantaneous} frequencies (f m1, f _m2 , f _m3 ) and thus that of the excitation frequencies ( f _A ) within an ultrasonic burst ( UB ) sinks. The start frequency ( f _1s ) of the first frequency curve ( SF1 ) within an ultrasonic burst ( UB ) is approaching the object ( O ) changes. First the start frequency ( f _1s ) of the first frequency curve ( SF1 ) within an ultrasonic burst approaching the object ( O ) is raised, and then falls off again when you get closer. In the example of FIG 20th a single mode time (smt) in which only the partial ultrasound burst with the first frequency curve ( SF1 ) is sent out. A period of the emission of the ultrasonic burst ( UB ) has a dual-mode time (dmt) in which only the partial ultrasound bursts with the first frequency profile ( SF1 ) and with the second frequency curve ( SF3 ) are sent out. Another part of the ultrasonic bursts has a tri-mode time (tmt) in which the ultrasonic partial bursts with the first frequency curve ( SF1 ) and with the second frequency curve ( SF3 ) and with the third frequency curve ( SF3 ) are sent out

Figure 21

21 illustrates the situation when using two ultrasonic sensor systems ( USS1 , USS2 ).

In this example, each of the two ultrasonic sensor systems ( USS1 , USS2 ) in the example of the ultrasonic sensor system ( USS ) the 11 .

Each of the ultrasonic sensor systems ( USS1 , USS2 ) receives accordingly when using different opening angles 18th and different instantaneous ultrasonic frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic sensor system, three different ultrasonic reflection signals with different instantaneous ultrasonic frequencies (f _m1 , f _m2 , f _m3 ). These three ultrasonic reflection signals received, for example, can already be used in the ultrasonic sensor system ( USS1 , USS2 ) are evaluated and then transmitted to a control unit (SG) or compressed unevaluated and largely unprocessed, transmitted to a control unit (SG), and then evaluated in the control unit (SG). Depending on the distance ( s1 , s2 ) of the object ( O ) from the respective ultrasonic sensor system ( USS1 , USS2 ) the ultrasonic reflection signal hits the respective ultrasonic sensor system at different times ( USS1 , USS2 ), which can also be evaluated.

Figure 22

22nd shows the effect of the various ultrasonic bursts in terms of their Doppler resistance.

22nd shows four examples for the influence of the ultrasonic bust frequency bandwidth and the frequency modulation curvature on Doppler-related distance errors at a driving speed of 8 ms ^-1 . The top row shows spectrograms of four ultrasonic burst echo pairs. The bottom row shows the envelope curves of the associated cross-correlation function (CCF signal) between the transmitted ultrasonic burst signal of the moving vehicle and the signal reflected by a stationary object after reception by the ultrasonic sensor system located in the moving vehicle. The arrows indicate the actual time delay of 8 ms between the time of transmission and the time of reception of the echo. The vertical lines show the position of the peak in the CCF signal.

As can easily be seen, a greater broadband quality of the ultrasonic burst leads to a reduction in the Doppler error.

For frequency measurement of frequencies that are present at the same time

For the sake of clarity, it should be mentioned briefly here how the presence of several frequencies is to be measured at a point in time.

Samples of the signal to be assessed are continuously stored as memory values. A storage time can always be assigned to the stored values. The stored values are multiplied by a window signal. This can be, for example, one of the following window signals: Rectangular window, Von-Hann window, Hamming window, Blackman window, Blackman-Harris window, Blackman-Nuttall window, flat-top window, Bartlett window Windows, Bartlett-Hann windows, Cosine windows, Tukey windows, Lanczos windows, Kaiser windows, Gaussian windows. Other window types are conceivable. The window function has a reference point in time. The length of the relevant window should be shorter than the ultrasonic burst duration ( bd ) be. The length of the relevant window should preferably be less than 1/10 of the ultrasonic burst duration ( bd ) be. The stored values are multiplied by the window function for the relevant reference point in time. In this case, a storage value is always multiplied by the value of the window signal to form a windowed sampling value, the point in time of which within the window signal, taking into account the reference point in time, corresponds to the point in time of sampling of the storage value. The windowed sample values then result in a windowed signal that can be subjected to a Fourier transformation or a Z transformation. If there are several frequencies in the transformed signal, then there are several frequencies in the signal at the reference time. The reference point in time is shifted and the same analysis is repeated over and over again. The process is known as time-frequency analysis (TFA).

List of reference symbols

A.

Ultrasonic burst amplitude;

A1

first spectral ultrasonic burst amplitude of the first ultrasonic transducer ( US1 );

A2

second spectral ultrasonic burst amplitude of the second ultrasonic transducer ( US2 );

A3

third spectral ultrasonic burst amplitude of the third ultrasonic transducer ( US3 );

Amax1

first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ). The first amplitude maximum ( A _max1 ) the sound radiation can be measured by stimulating the first ultrasonic transducer ( US1 ) with a first excitation frequency ( f _A1 ), where the first excitation frequency ( f _A1 ) is tuned and that first excitation frequency ( f _A1 ) is determined, in which the first ultrasonic transmitter ( US1 ) absorbs the maximum active power. In this document, the sound power emitted in the process is referred to as the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) understood;

Amax2

second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ). The second amplitude maximum ( A _max2 ) the sound radiation can be measured by stimulating the second ultrasonic transducer ( US2 ) with a second excitation frequency ( f _A2 ), with the second excitation frequency ( f _A2 ) is tuned and that second excitation frequency ( f _A2 ) is determined, in which the second ultrasonic transmitter ( US2 ) absorbs the maximum active power. The sound power emitted during this process is referred to in this document as the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) understood;

Amax3

third amplitude maximum ( A _max3 ) the Sound emission of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ). The third amplitude maximum ( A _max3 ) the sound radiation can be measured by stimulating the third ultrasonic transducer ( US3 ) with a third excitation frequency ( f _A3 ), with the third excitation frequency ( f _A3 ) is tuned and the third excitation frequency ( f _A3 ) is determined, in which the third ultrasonic transmitter ( US3 ) absorbs the maximum active power. In this document, the sound power emitted in the process is referred to as the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) understood;

AS

Control signal;

AS1

first control signal of the first ultrasonic transducer ( US1 );

AS2

first control signal of the second ultrasonic transducer ( US2 );

AS3

first control signal of the third ultrasonic transducer ( US3 );

AV

Control device;

AV1

first control device of the first ultrasonic transducer ( US1 );

AV2

second control device of the second ultrasonic transducer ( US2 );

AV3

third control device of the third ultrasonic transducer ( US3 );

bd

Burst duration of an ultrasonic burst. The burst duration begins with the ultrasonic burst start ( UBS ) and ends with the end of the ultrasonic burst ( UBE );

D.

Object distance between the next relevant object and the ultrasonic measuring system;

Δf1

first bandwidth of the first ultrasonic transducer ( US1 ). The first bandwidth is the first upper half-maximum amplitude frequency ( f _1o ), where the amplitude ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ) minus the first lower half-maximum amplitude frequency ( f _1u ), where the amplitude ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) also half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ) amounts to;

Δf12

Frequency difference between the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 ) and the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 );

Δf2

second bandwidth of the second ultrasonic transducer ( US2 ). The second bandwidth is the second upper half-maximum amplitude frequency ( f _2o ), where the amplitude ( A. ) the sound radiation of the second ultrasonic transducer ( US2 ) half of the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ) minus the second lower half-maximum amplitude frequency ( f _2u ), where the amplitude ( A. ) the sound radiation of the second ultrasonic transducer ( US2 ) also half of the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ) amounts to;

Δf23

Frequency difference between the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 ) and the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 );

Δf3

third bandwidth of the third ultrasonic transducer ( US3 ). The third bandwidth is the third upper half-maximum amplitude frequency ( f _3o ), where the amplitude ( A. ) the sound radiation of the third ultrasonic transducer ( US3 ) half of the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ) minus the third lower half-maximum amplitude frequency ( f _3u ), where the amplitude ( A. ) the sound radiation of the third ultrasonic transducer ( US3 ) also half of the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ) amounts to;

Δfg

Total frequency bandwidth of the ultrasonic sensor system ( USS );

dmt12

second dual mode time in 12th , in which the first ultrasonic transducer ( US1 ) and the second ultrasonic transducer ( US2 ) Emit sound;

dmt23

first dual mode time in 12th , in which the third ultrasonic transducer ( US3 ) and the second ultrasonic transducer ( US2 ) Emit sound;

f1

first resonance frequency of the first ultrasonic transducer ( US1 ). The first resonance frequency of the first ultrasonic transducer ( US1 ) is determined in the sense of this document in such a way that the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) by detuning the first excitation frequency ( f _A1 ) of the first ultrasonic transducer ( US1 ) with preferably at least locally constant excitation amplitude of the first excitation signal ( AS1 ) of the first ultrasonic transducer ( US1 ) is searched. The first amplitude maximum ( A _max1 ) can be done by stimulating the first ultrasonic transducer ( US1 ) with a first excitation frequency ( f _A1 ), where the first excitation frequency ( f _A1 ) is tuned and that first excitation frequency ( f _A1 ) is determined, in which the first ultrasonic transmitter ( US1 ) absorbs the maximum active power. In this document, the sound power emitted in the process is referred to as the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) understood. The first excitation frequency ( f _A1 ) at which this first amplitude maximum ( A _max1 ) occurs, the first resonance frequency of the first ultrasonic transducer is ( US2 );

f1 / 50%

first half frequency. The first half frequency results as f _1/50% = (f _1s -f _1e ) / 2 + f _1e ;

f1e

first end frequency;

f1m

first ultrasonic burst instantaneous frequency with which the first ultrasonic transmitter ( US1 ) Emits sound;

f1o

first upper half-maximum amplitude frequency ( f _1o ). At the first upper half-maximum amplitude frequency ( f _1o ) the amplitude is ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ). The first upper half-maximum amplitude frequency ( f _1o ) of the first ultrasonic transducer ( US1 ) is above the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 );

f1s

first start frequency;

f1u

first lower half-maximum amplitude frequency ( f _1u ). At the first lower half-maximum amplitude frequency ( f _1u ) the amplitude is ( A. ) the sound radiation of the first ultrasonic transducer ( US1 ) half of the first amplitude maximum ( A _max1 ) the sound radiation of the first ultrasonic transducer ( US1 ) at its first resonance frequency ( f ₁ ). The first lower half-maximum amplitude frequency ( f _1u ) of the first ultrasonic transducer ( US1 ) is below the first resonance frequency ( f ₁ ) of the first ultrasonic transducer ( US1 );

f2

second resonance frequency of the second ultrasonic transducer ( US2 ). The second resonance frequency of the second ultrasonic transducer ( US2 ) is determined in the sense of this document in such a way that the second amplitude maximum ( A _max2 ) the Sound emission of the second ultrasonic transducer ( US2 ) by detuning the second excitation frequency ( f _A2 ) of the second ultrasonic transducer ( US2 ) with the excitation amplitude of the second excitation signal of the second ultrasonic transducer preferably at least locally constant over time ( US2 ) is searched. The second amplitude maximum ( A _max2 ) can be done by stimulating the second ultrasonic transducer ( US2 ) with a second excitation frequency ( f _A2 ), with the second excitation frequency ( f _A2 ) is tuned and that second excitation frequency ( f _A2 ) is determined, in which the second ultrasonic transmitter ( US2 ) absorbs the maximum active power. The sound power emitted during this process is referred to in this document as the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) understood. That second excitation frequency ( f _A2 ) at which this second amplitude maximum ( A _max2 ) occurs, the second resonance frequency of the second ultrasonic transducer is ( US2 );

f2 / 50%

second half frequency. The second half frequency results as f _2/50% = (f _2s -f _2e ) / 2 + f _2e ;

f2e

second end frequency;

f2m

second instantaneous ultrasonic burst frequency with which the second ultrasonic transmitter ( US2 ) Emits sound;

f2o

second upper half-maximum amplitude frequency ( f _2o ). At the second upper half-maximum amplitude frequency ( f _2o ) the amplitude is ( A. ) the sound radiation of the second ultrasonic transducer ( US2 ) half of the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ). The second upper half-maximum amplitude frequency ( f _2o ) of the second ultrasonic transducer ( US2 ) is above the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 );

f2s

second start frequency;

f2u

second lower half-maximum amplitude frequency ( f _2u ). At the second lower half-maximum amplitude frequency ( f _2u ) the amplitude is ( A. ) the sound radiation of the second ultrasonic transducer ( US2 ) half of the second amplitude maximum ( A _max2 ) the sound radiation of the second ultrasonic transducer ( US2 ) at its second resonance frequency ( f ₂ ). The second lower half-maximum amplitude frequency ( f _2u ) of the second ultrasonic transducer ( US2 ) is below the second resonance frequency ( f ₂ ) of the second ultrasonic transducer ( US2 );

f3

third resonance frequency of the third ultrasonic transducer ( US3 ). The third resonance frequency of the third ultrasonic transducer ( US3 ) is determined in the sense of this document in such a way that the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) by detuning the third excitation frequency ( f _A3 ) of the third ultrasonic transducer ( US3 ) with preferably at least locally constant excitation amplitude of the third excitation signal of the third ultrasonic transducer ( US3 ) is searched. The third amplitude maximum ( A _max3 ) can be done by stimulating the third ultrasonic transducer ( US3 ) with a third excitation frequency ( f _A3 ), with the third excitation frequency ( f _A3 ) is tuned and the third excitation frequency ( f _A3 ) is determined, in which the third ultrasonic transmitter ( US3 ) absorbs the maximum active power. In this document, the sound power emitted in the process is referred to as the third amplitude maximum ( A _max3 ) the sound radiation of the first ultrasonic transducer ( US1 ) understood. That third excitation frequency ( f _A3 ) at which this third amplitude maximum ( A _max3 ) occurs is the third resonance frequency of the third ultrasonic transducer ( US3 );

f3 / 50%

third half frequency. The third half frequency results as f _3/50% = (f _3s -f _3e ) / 2 + f _3e ;

f3e

third end frequency;

f3m

third ultrasonic burst instantaneous frequency with which the third ultrasonic transmitter ( US3 ) Emits sound;

f3o

third upper half-maximum amplitude frequency ( f _3o ). At the third upper half-maximum amplitude frequency ( f _3o ) the amplitude is ( A. ) the sound radiation of the third ultrasonic transducer ( US3 ) half of the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ). The third upper half-maximum amplitude frequency ( f _3o ) of the third ultrasonic transducer ( US3 ) is above the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 );

f3s

third start frequency;

f3u

third lower half-maximum amplitude frequency ( f _3u ). At the third lower half-maximum amplitude frequency ( f _3u ) the amplitude is ( A. ) the sound radiation of the third ultrasonic transducer ( US3 ) half of the third amplitude maximum ( A _max3 ) the sound radiation of the third ultrasonic transducer ( US3 ) at its third resonance frequency ( f ₃ ). The third lower half-maximum amplitude frequency ( f _3u ) of the third ultrasonic transducer ( US3 ) is below the third resonance frequency ( f ₃ ) of the third ultrasonic transducer ( US3 );

fa

Control instantaneous frequency;

fA1

first control frequency of the first ultrasonic transducer ( US1 );

fA1 / 50%

first half frequency drive frequency;

fA1e

first final drive frequency;

fA1s

first start control frequency;

fA2

second control frequency of the second ultrasonic transducer ( US2 );

fA2 / 50%

second half frequency drive frequency;

fA2e

second final drive frequency;

fA2s

second start control frequency;

fA3

third control frequency of the third ultrasonic transducer ( US3 );

fA3 / 50%

third half frequency drive frequency;

fA3e

third final drive frequency;

fA3s

third start control frequency;

fm

Ultrasonic burst instantaneous frequency;

fm, 0

zeroth instantaneous ultrasonic frequency of the zeroth ultrasonic pulse ( P ₀ ) in the zeroth ultrasound period with the zeroth ultrasound period ( T ₀ ) within an ultrasonic burst ( UB );

fm, 1

first ultrasonic instantaneous frequency of the first ultrasonic pulse ( P ₁ ) in the first ultrasound period with the first ultrasound period ( T ₁ ) within an ultrasonic burst ( UB );

fm, 2

second ultrasonic instantaneous frequency of the second ultrasonic pulse ( P ₂ ) in the second ultrasound period with the second ultrasound period ( T ₂ ) within an ultrasonic burst ( UB );

fm, 3

third ultrasonic instantaneous frequency of the third ultrasonic pulse ( P ₃ ) in the third ultrasound period with the third ultrasound period ( T ₃ ) within an ultrasonic burst ( UB );

fm, 4

fourth ultrasonic instantaneous frequency of the fourth ultrasonic pulse ( P ₄ ) in the fourth ultrasound period with the fourth ultrasound period ( T ₄ ) within an ultrasonic burst ( UB );

fm, 5

fifth ultrasonic instantaneous frequency of the fifth ultrasonic pulse ( P ₅ ) in the fifth ultrasound period with the fifth ultrasound period ( T ₅ ) within an ultrasonic burst ( UB );

fm, 6

sixth instantaneous ultrasonic frequency of the sixth ultrasonic pulse ( P ₆ ) in the sixth ultrasound period with the sixth ultrasound period ( T ₆ ) within an ultrasonic burst ( UB );

fm, 7

seventh instantaneous ultrasonic frequency of the seventh ultrasonic pulse ( P ₇ ) in the seventh ultrasound period with the seventh ultrasound period ( T ₇ ) within an ultrasonic burst ( UB );

fm, j

jth instantaneous ultrasonic frequency of the jth ultrasonic pulse ( P _j ) in the j th ultrasound period with the j th ultrasound period ( T _j ) within an ultrasonic burst ( UB ) (here j stands for a whole positive number);

O

Object;

O1

first object;

O2

second object;

P0

zeroth ultrasonic pulse in the zeroth ultrasonic period of the exemplary ultrasonic bursts ( UB ) the 2a ;

P1

first ultrasonic pulse in the first ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

P2

second ultrasonic pulse in the second ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

P3

third ultrasonic pulse in the third ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

P4

fourth ultrasonic pulse in the fourth ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

P5

fifth ultrasonic pulse in the fifth ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

P6

sixth ultrasonic pulse in the sixth ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

P7

seventh ultrasonic pulse in the seventh ultrasonic period of the exemplary ultrasonic burst ( UB ) the 2a ;

Pj

j-th ultrasonic pulse in the j-th ultrasonic period of the exemplary ultrasonic burst ( UB ) (here j stands for a whole positive number);

SF1

first frequency curve of the instantaneous ultrasonic burst frequency ( f _m ) or the first ultrasonic _{burst instantaneous} frequency (f m1) of a first ultrasonic partial burst within an ultrasonic burst ( UB );

SF2

second frequency curve of the second ultrasonic _{burst instantaneous} frequency (f m2) of a second ultrasonic partial burst within an ultrasonic burst ( UB ). Within the ultrasonic burst ( UB ) this second partial ultrasound burst is typically superimposed on the first partial ultrasound burst, preferably by summation;

SF3

third frequency curve of the third ultrasonic _{burst instantaneous} frequency (f m3) of a third ultrasonic partial burst within an ultrasonic burst ( UB ). Within the ultrasonic burst ( UB ) this third partial ultrasound burst is typically superimposed on the first partial ultrasound burst and the second partial ultrasound burst, preferably by summation;

s1

first distance of the first ultrasonic sensor system ( USS1 ) from the object ( O )

s2

second distance of the second ultrasonic sensor system ( USS2 ) from the object ( O )

smt1

first single-mode period;

smt2

second single-mode period;

smt3

third single-mode period;

United States

Ultrasound system axis;

USS

Ultrasonic sensor system;

USS1

first ultrasonic sensor system;

USS2

second ultrasonic sensor system;

t

Time;

t1 / 50%

first half-frequency time. At this first half-frequency time ( t _1/50% ) the first ultrasonic transducer sends ( US1 ) with a first half frequency ( f _1/50% );

t1a

first temporal burst phase;

t1b

second temporal burst phase;

t1s

first transmission start time;

t1e

first sending end time;

t2 / 50%

second half-frequency time. At this second half-frequency time ( t _2/50% ) sends the second ultrasonic transducer ( US2 ) with a second half frequency ( f _2/50% );

t2s

second transmission start time;

t2e

second sending end time;

t3 / 50%

third half-frequency time. At this third half-frequency time ( t _3/50% ) sends the third ultrasonic transducer ( US3 ) with a second half frequency ( f _3/50% );

t3s

third transmission start time;

t3e

third transmission end time;

T0

zeroth ultrasonic period of the zeroth ultrasonic period of the zeroth ultrasonic pulse ( P ₀ );

T1

first ultrasound period of the first ultrasound period of the first ultrasound pulse ( P ₁ );

T2

second ultrasound period of the second ultrasound period of the second ultrasound pulse ( P ₂ );

T3

third ultrasound period of the third ultrasound period of the third ultrasound pulse ( P ₃ );

T4

fourth ultrasound period of the fourth ultrasound period of the fourth ultrasound pulse ( P ₄ );

T5

fifth ultrasound period of the fifth ultrasound period of the fifth ultrasound pulse ( P ₅ );

T6

sixth ultrasound period of the sixth ultrasound period of the sixth ultrasound pulse ( P ₆ );

T7

seventh ultrasound period of the seventh ultrasound period of the seventh ultrasound pulse ( P ₇ );

Tj

j-th ultrasonic period of the j-th ultrasonic period of the j-th ultrasonic pulse ( P _j ) (here j stands for a whole positive number);

UB

Ultrasonic burst;

UBS

Ultrasonic burst start;

UBE

Ultrasonic burst end

US1

first ultrasonic transducer;

US2

second ultrasonic transducer;

US3

third ultrasonic transducer;

USS

Ultrasonic sensor system;

USS1

first ultrasonic sensor system;

USS2

second ultrasonic sensor system;

vf

Frequency change rate of the instantaneous ultrasonic burst frequency ( f _m ) over time ( t );

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2010/063510 A1 [0004]
• EP 1231481 A2 [0005]
• US 7693007 B2 [0006]

Claims (6)

A method for emitting an ultrasonic burst for use in ultrasonic sensor systems in vehicles, comprising the steps Step 1: transmission of an ultrasonic burst with an ultrasonic burst duration (bd) which does not exceed a maximum ultrasonic burst duration (bd) by an ultrasonic sensor system (USS); - Step 2: receiving an ultrasonic burst reflected by an object (O); - Step 3: determining the distance (D) between the ultrasonic sensor system (USS) and the object (O) as a function of the received reflected ultrasonic burst; - Step 4: Repeat steps 1 to 4, the ultrasonic burst duration (bd) depending on the determined distance (s1, s2), characterized in that - that the temporal ultrasonic burst interval of the ultrasonic bursts becomes shorter with decreasing spatial distance (D) between the ultrasonic sensor system and the object (O). Procedure according to Claim 1 ^{- where the ultrasonic burst length} (bd) is increased with the fourth root of the determined distance (D) according to the formula bd = bd ₁ * D -1/4 + bdo with bd ₀ and bd ₁ as constants. Procedure according to Claim 1 and / or 2 - where the amplitude (A) of the emitted ultrasonic _{burst is essentially proportional to (D + D 0} ) ^{1 / k} , with 2 k 5 or preferably k = 2 or k = 4, from the determined distance (A ), where D _{0 is} a constant that can be zero. Method according to one or more of the Claims 1 until 3 - wherein at least several ultrasonic bursts (UB) are emitted in a temporal ultrasonic burst interval and - wherein the first temporal ultrasonic burst interval is the time interval between the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst and between is the ultrasonic burst start (UBS) of a first ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this first ultrasonic burst and - the second ultrasonic burst interval between the ultrasonic burst start (UBS) of the second ultrasonic burst and the ultrasonic burst start (UBS) of the second ultrasonic burst immediately following this subsequent third ultrasonic burst depends on the determined distance (D). Method according to one or more of the Claims 1 until 4th - where the temporal ultrasonic burst interval of the ultrasonic bursts with a shortening of the spatial distance (D) between the ultrasonic sensor system and the object (O) by a length I temporally by a time 2 * l / c with c as the speed of sound with a tolerance of +/- 25% and / or is shorter with a tolerance of +/- 10% and / or with a tolerance of +/- 5%. Method according to one or more of the Claims 1 until 5 - where the number of instantaneous ultrasonic _burst frequencies (f m1, f _m2 , f _m3 ) and the associated number of frequency profiles (SF1, SF2, SF3) of these instantaneous ultrasonic burst frequencies (f _m1 , f _m2 , f _m3 ) within an ultrasonic burst (UB) from the distance ( D) depends.

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