DE102017116013A1 - Information device and method for checking the function of an information device - Google Patents

Abstract

An information device for outputting an indication, preferably in the form of an audio-acoustic signal, is described, wherein the information device comprises at least one memory (1) with at least one reference signal (A (t)), at least one processing unit (18) for generating an output signal (AM (t)) based on the strobe signal (A (t)), at least one output unit (4) for outputting the output signal (AM (t)), at least one verification unit (5) comprising:
- At least one folding element (6) for folding (F1) of the output signal (AM (t)) with a comparison signal (G (t)), for example, the indication signal (A (t)), and
- For folding (F2) of the output signal (AM (t)) with the by a displacement time (T) offset comparison signal (G (t + T)), for example, the indication signal (A (t + T)), and
- At least one warning element that outputs based on the results (E1, E2) of the convolutions (F1, F2) a warning signal and / or logged.

Description

The invention relates to an information device and a method for checking the function of an information device.

Signals can be found in a wide variety of application areas and are used with a wide variety of destinations. In the area of passenger transport, signals are used for entertainment as well as information, as a hint or warning. The term "signal" can be broadly subdivided into visual signals, such as a flashing light source, haptic signals, such as the vibration of a steering wheel, and acoustic signals, such as an acoustic voice output of a navigation system, for the passenger transport sector. In particular, in vehicles signals are used both to inform the occupants of a motor vehicle, as well as to warn the other road users.

So it is common before the start of the powertrain of a motor vehicle that the instrument panel is initialized and a functional test derselbigen is performed. The instrument panel is usually located in the field of vision of the driver and serves to display visual warning signals such as a malfunction of an airbag system, a critical oil level, or too low a tire pressure. Usually, all visual warning signals of the instrument panel light up when an ignition key is operated for a short period of time, so that the driver of the vehicle can visually check the operation based on the presence of the visual warning signals. Should a visual warning light fail to light up, the driver can quickly detect this and initiate a correction of the fault.

With advanced development of motor vehicles is a purely visual warning, especially because of their high number of signals, confusing and consuming for the driver. In particular, due to the ever increasing number of sensors in a motor vehicle, the number of possible warning signals has risen so much that a purely visual check of the functionality of the visual warning signals opens into a distraction from the actual driver operation. Furthermore, highly automated vehicle systems are developed which enable the driver to engage in other activities, such as watching entertainment films. Thus, the visual warning signals are no longer in the driver's field of vision.

For this reason, in addition to visual warning signals and acoustic warning signals are increasingly used. An example of an audible warning signal is a parking assist system that emits a sound depending on a distance between an obstacle and a sensor that is often located at the rear of the vehicle. In the case of the parking assist system, it is common for a visual warning signal to be displayed in addition to the audible warning signal which allows a visual distance estimation by means of a screen in the center console.

In vehicles, the absence of a warning signal due to a defect can cause damage to the vehicle or endanger the occupants of the vehicle. Even wrong or poorly tuned to the environment signals can be highly problematic.

It is thus an object of the present invention to eliminate or at least minimize the disadvantages known from the prior art. In particular, it is an object of the present invention to increase the safety in the interaction with a vehicle.

The object is achieved by a hinting device according to claim 1, by a method according to claim 11 and by a computer-readable medium according to claim 15.

• mindestens einen Speicher mit mindestens einem Hinweissignal,
• mindestens ein Verarbeitungseinheit zum Erzeugen eines Ausgabesignals, das auf dem Hinweissignal basiert,
• mindestens eine Ausgabeeinheit, zur Ausgabe des Ausgabesignals, gekennzeichnet, durch
• mindestens eine Überprüfungseinheit, aufweisend:
  • - mindestens ein Faltelement zum Falten des Ausgabesignals mit einem Vergleichssignal, z.B. dem Hinweissignal, und zum Falten des Ausgabesignals mit dem um eine Versetzungszeit versetzten Vergleichssignal, z.B. dem Hinweissignal, und
  • - mindestens ein Warnelement, das basierend auf den Ergebnissen der Faltungen ein Warnsignal ausgibt und/oder protokolliert.

In particular, the object is achieved by an indicating device for outputting a hint, preferably in the form of an audio-acoustic signal, the device comprising:

• at least one memory with at least one notification signal,
• at least one processing unit for generating an output signal based on the indication signal,
• at least one output unit for outputting the output signal, characterized by
• at least one review unit, comprising:
  • at least one folding element for folding the output signal with a comparison signal, for example the indication signal, and for folding the output signal with the offset by a displacement time comparison signal, for example, the indication signal, and
  • - At least one warning element that outputs a warning signal based on the results of the convolutions and / or logged.

The term "unit" can be used in the present application to describe both a physical unit and a logical unit. Also, the term "element" can be both a physical element and a logical element to be discribed. For example, it may be that the verification unit is implemented by dedicated hardware or software. It is also possible, for example, for the checking unit to be realized by one or more logical elements, such as functions, processes and / or code segments. The same applies to the units and elements listed in the previous and following sections.

As already explained, it has turned out to be a problem with regard to acoustic warning signals to ensure that the correct acoustic warning signal is output. While with a visual warning signal, the actual warning signal is either displayed correctly, the light source is lit or not, there are a variety of possible sources of error for audible warning signals. For example, the correct audible warning signal may have been selected by a system, but due to a processing error in the conversion, it may be possible that the audible warning signal is distorted or reproduced at too low a volume. Also, an error in an output device, such as a loudspeaker, may cause the system to issue an audible warning, but this warning signal will not be output by the defective output device. Another potential error is that a malfunction will result in a false audible warning. Thus, for example, it is possible that instead of the acoustic warning signal, which should alert the driver to a sudden pressure drop in a tire, the acoustic warning signal is reproduced for a distance sensor. In particular, with regard to the progressive development in the field of highly automated or semi-automated motor vehicles, this can lead to an increased risk of accidents. This is because, in the case of highly automated motor vehicles, the driver is engaged in non-driving activities such as e-mail editing, watching movies, and does not perceive any visual warning signal that may be output and is not alerted by the false audible warning.

Acoustic warning signals have a certain amount of information redundancy. Even if individual sound sequences are reproduced in a changed pitch, a changed rhythm, or the like, the driver recognizes the signal due to the similar sound. Thus, acoustic warning signals do not have to be completely correct, but must have a certain degree of similarity to the actual signal to be reproduced.

The present invention solves these problems by providing a check on the operability of the pointer in advance, e.g. during commissioning of the vehicle, and / or during operation. A particular advantage of the pointing device according to the invention is that the indication signal can be checked by the folding element. In particular, the results of the convolutions allow conclusions to be drawn about which alert signal was used. The convolutions allow a check for "signal similarity". Based on these results of the convolutions, a warning signal can be issued and / or logged by a warning element. A driver is alerted by the warning signal that an incorrect warning signal has been issued. In addition, it is possible for a service provider, for example, to read out logs of the warning element in order to determine the exact cause of the error for the output of the false notification signal.

In one embodiment, the verification unit comprises at least one calculation element that calculates a quotient between the result of the first convolution and the result of the second convolution.

By such a calculation, a quotient is formed, which has no amplitude dependence, whereby a narrow valid result space is achieved. As a result, the verifiability of the correctness of the notification signal is further improved.

1. a) der Quotient größer als ein erster Schwellwert ist, z.B. Q>S1, und/oder
2. b) das Ergebnis der ersten Faltung größer als ein zweiter Schwellwert ist, z.B. S2<E1, und/oder
3. c) das Ergebnis der ersten Faltung kleiner als ein dritter Schwellwert (S3) ist, z.B. E1<S3.

In a further embodiment, the checking unit is designed to then issue no warning signal and / or to log, if

1. a) the quotient is greater than a first threshold value, eg Q> S1, and / or
2. b) the result of the first convolution is greater than a second threshold value, eg S2 <E1, and / or
3. c) the result of the first convolution is smaller than a third threshold (S3), eg E1 <S3.

On the one hand, it is possible to check by means of such test steps whether the amplitude of the reference signal lies within an expected range, ie, corresponds to the amplitude as originally output. On the other hand, a check of the notification signal in the time domain is possible by such test steps. By means of these test steps, the correctness of the output signal with respect to the warning signal can thus be checked further.

According to a further embodiment, the processing unit has at least one amplifier element which amplifies the indication signal by a gain factor and mixes the result of the amplification with a background signal in order to obtain the output signal, eg AM (t) = A (t) * a + R (t), wherein the gain factor is preferably determined based on a speed and / or a loudness.

An advantage of this embodiment is that the volume of the output signal in response to environmental influences, such as the speed and / or possibly activated entertainment systems such as a radio, can be changed. As a result, an improved perceptibility of the notification signal is achieved.

In a further embodiment, the comparison signal is not identical to the output signal, wherein a correlation factor p is at least 5% less than 1 and at least 5% greater than -1.

An advantage of the non-identity of the comparison signal to the output signal is the avoidance or at least minimization of coupled errors. For example, an error in the signal processing can corrupt both the original strobe signal and the convolution operation. The dissimilarity of the comparison signal and the output signal can be determined by means of a correlation factor p.

In a further embodiment, the correlation factor p is greater than 0.5, in particular greater than 0.7.

An advantage of this embodiment is that an improved verifiability of the output signal is achieved by such a correlation factor, since the output signal is based on the strobe signal, but the former is at least amplified. It is thus possible to define a narrower result space.

The correlation factor p describes the similarity of the comparison signal and the indication signal. For the correlation factor ρ, ρ ² ≦ 1 always holds. A correlation factor p of 1 corresponds to a correlation of the comparison signal and the indication signal. The two signals are in the same direction. A correlation factor p of -1 corresponds to an opposition of the comparison signal and the indication signal. A correlation factor p of 0 corresponds to an orthogonality of the indication signal and the comparison signal. The two signals are uncorrelated.

According to a further embodiment, the processing unit has at least one mixing element which mixes the output signal or the notification signal with at least one entertainment signal, for example a radio reproduction signal, and / or an assistance signal, for example a driver assistance system output.

By the mixing element, it is possible that signals that are already reproduced, such as a radio broadcast, are not completely stopped to output the output signal, but are throttled in volume, for example, to achieve a perceptible reproduction of the output signal.

In a further embodiment, the hint device has a receiving element, in particular a microphone, which receives the output signal, and the hint device has an analog / digital converter, which converts the output signal, and transmits it to the checking unit.

An advantage of the pickup element is that it picks up the output signal output by a display element as well as noise and converts it through the analog-to-digital converter. This makes it possible that the actual playback and the quality of this playback are taken into account in the review of the notification signal.

According to a further embodiment, the analog-to-digital converter samples the recorded output signal at a sampling rate which is less than a sampling rate of the comparison signal and / or the indication signal.

An advantage of this embodiment is that a smaller sample rate achieves data reduction.

The object is also achieved by a vehicle, in particular a motor vehicle, having at least one pointing device according to one of the preceding embodiments. The advantages already described can also be achieved by integrating at least one hint device according to one of the preceding embodiments into a vehicle, in particular a motor vehicle.

• - Erfassen eines Ausgabesignals der Hinweisvorrichtung,
• - Auslesen eines Vergleichssignals,
• - erstes Falten des Ausgabesignals mit dem Vergleichssignal, z.B. einem Hinweissignal,
• - zweites Falten des Ausgabesignals mit dem um eine Versetzungszeit versetzten Vergleichssignal, und
• - Ausgeben eines Warnsignals und/oder Protokollieren des Warnsignals basierend auf Ergebnissen der Faltungen.

Likewise, the object is achieved by a method for checking the function of an indicating device, which issues an indication, the method comprising the steps:

• Detecting an output signal of the information device,
• - reading a comparison signal,
• first folding of the output signal with the comparison signal, eg an indication signal,
• second folding of the output signal with the offset signal offset by an offset time, and
• Outputting a warning signal and / or logging the warning signal based on results of the convolutions.

The hint device may be one of the hint devices described above.

According to the invention, the warning signal can be checked by the two folds. In particular, the results of the convolutions allow conclusions to be drawn about which alert signal was used. Based on these results of the convolutions, a warning signal can be output and / or the warning signal can be logged. A driver is alerted by the warning signal that an incorrect warning signal has been issued. In addition, it is possible for a service provider, for example, to read logs of the warning signal in order to determine the exact cause of the error for the output of the false warning signal.

In another embodiment, the method of the invention includes the step of forming a quotient between the result of the first convolution and the result of the second convolution.

By such a calculation, a quotient is formed, which has no amplitude dependence, whereby a narrow valid result space is achieved. As a result, the verifiability of the correctness of the notification signal is further improved.

• - Vergleichen des Quotienten in einem ersten Prüfschritt mit einem ersten Schwellwert, und
• - Vergleichen, in einem zweiten Prüfschritt, eines zweiten Schwellwerts mit dem Ergebnis der ersten Faltung, und
• - Vergleichen, in einem dritten Prüfschritt, des Ergebnisses der ersten Faltung mit einem dritten Schwellwert (S3), und
• - Ausgeben eines Warnsignals und/oder Protokollieren, wenn
  1. a) der Quotient kleiner als der erste Schwellwert ist, und
  2. b) das Ergebnis der ersten Faltung zwischen dem dritten und zweiten Schwellwert liegt.

Furthermore, the method according to the invention comprises the following steps:

• Comparing the quotient in a first test step with a first threshold value, and
• Comparing, in a second test step, a second threshold value with the result of the first convolution, and
• Comparing, in a third test step, the result of the first convolution with a third threshold value (S3), and
• - Issuing a warning signal and / or logging when
  1. a) the quotient is less than the first threshold, and
  2. b) the result of the first convolution is between the third and second thresholds.

By a method with such steps, it is on the one hand verifiable whether the amplitude of the hint signal is within an expected range. On the other hand, a check of the notification signal in the time domain is possible by such test steps. Through these test steps, the correctness of the output signal with respect to the warning signal can be further checked.

It is also advantageous if the sampling rate for detecting the output signal is lower than a sampling rate of the notification signal, in particular by at least 10% or 20% or 30% or 50%.

An advantage of this embodiment is that a smaller sample rate of acquisition of the output signal results in data reduction.

The object is also achieved by a computer-readable medium having instructions which, when executed on one or more arithmetic units, implement a method according to one of the preceding embodiments.

The computer-readable medium according to the invention, including computer-executable instructions, results in an improved information-technical handling of the method according to the invention.

• 1: Eine erste mögliche Ausführungsform;
• 2: Eine zweite mögliche Ausführungsform mit Analog/DigitalWandler;
• 3: Eine dritte mögliche Ausführungsform;
• 4: Eine vierte mögliche Ausführungsform mit akustischem Wandler.

The invention will be described by means of several embodiments, which are explained in more detail with reference to figures. Hereby show:

• 1 : A first possible embodiment;
• 2 : A second possible embodiment with analog / digital converter;
• 3 : A third possible embodiment;
• 4 A fourth possible embodiment with acoustic transducer.

In the following description, the same reference numerals are used for identical and equivalent parts.

The 1 shows a first embodiment of the hint device according to the invention. In a store 1 There are one or more different signals. For better clarity are in the 1 only some of these signals are shown as blocks.

An indication signal A (t), where the "t" written in parentheses means a dependence on time, is read from the memory 1 read out and sent to a processing unit 18 passed. The processing unit 18 includes an amplifier 2 and a mixing element 3 , The amplifier 2 amplifies the indication signal A (t) by a fixed or determinable factor and transmits the indication signal A (t) to the mixing element 3 , Similarly, an entertainment signal U (t) and an assistance signal N (t) is sent to the processing unit 18 pass and through each one amplifier 2 reinforced and to the mixing element 3 to hand over. Other signals, for example, on another memory like an external memory can also be the processing unit 18 pass and through a suitable amplifier 2 reinforced and through the mixing element 3 be merged.

The mixing element 3 mixes the hint signal A (t) with the entertainment signal U (t), the assistance signal N (t) and optionally with the other signals. That through the processing unit 18 signal generated in the embodiment of the 1 referred to as output signal AM (t).

In the exemplary embodiment, the output signal AM (t) is a digital signal. For this reason, the same becomes the digital / analog converter 10 the output unit 4 passed, which performs a conversion of the output signal AM (t) in an analog output signal AM (t). The signal obtained is optionally an analogue amplifier 11 passed and via a rendering element 7 , such as one or more speakers output.

The output signal AM (t) becomes parallel to the transfer to the output unit 4 a review unit 5 to hand over. This can be done for example by a signal branch or a signal splitter (not shown).

In the review unit 5 the output signal AM (t) becomes a first folding element 6 ' and another folding element 6 to hand over.

Parallel to this, the original indication signal A (t) becomes the first folding element 6 ' the verification unit 5 to hand over. Also, the notice signal A (t) becomes by means of a time shift element 15 offset by a displacement time T and the second folding element 6 to hand over.

The two folding elements 6 . 6 ' fold the signals applied to the respective inputs. The convolution of the indication signal A (t) with the output signal AM (t) is defined as a first convolution. The convolution of the delayed reference signal A (t + T) with the output signal AM (t) is defined in the present example as a second convolution. As based on the 1 As can be seen, the comparison signal G (t) can also be used instead of the indication signal A (t) for the convolutions described above. This would require the illustrated switch 16 which can also be implemented logically, be closed, so that the comparison signal G (t) instead of the indication signal A (t) to the respective inputs of the two folding elements 6 . 6 ' can be handed over. The time offset described above by means of the time shift element 15 can also be performed with the comparison signal G (t), so that the signal G (t + T) results.

The folding elements 6 . 6 ' perform the respective convolution operation and pass the respective convolution result E1, E2 to a calculation element 8th , The latter performs a quotient calculation, wherein the first result E1 is divided by the second result E2 according to the formula Q = E1 / E2, where Q describes the quotient.

The quotient Q becomes a predicate 9 to hand over. Then the predicate compares 9 the quotient Q in a first test step with a first threshold S1. In a second test step, a second threshold value S2 is compared with the result E1 of the first convolution F1, according to S2 <E1. In a third test step, the result E1 of the first convolution F1 is compared with a third threshold S3 according to E1 <S3. The first, second and third threshold values S1, S2, S3 are respectively defined by the comparison signal G (t).

In the event that the quotient Q or the result E1 of the first convolution F1, the three test steps of the predicate 9 fulfilled, the conditions are true, this means that the output signal AM (t) contains the indication signal A (t) or reproduces with sufficient accuracy. This is logged, for example. In the event that the quotient Q or the result E1 of the first convolution F1 does not fulfill one of the three test steps, a warning element is used 17 a warning is issued and / or the non-fulfillment of the test steps is logged. The warning element 17 may be, for example, an additional output unit. It is also possible, however, that the in the 1 illustrated output unit 4 as a warning element 17 acts.

The 2 and 3 each show an alternative embodiment. The basic procedure is the same as described in relation to the first embodiment. A difference between the embodiments of the 2 and 3 and the 1 is the different location of the signal pickup for transferring the output signal AM (t) to the folding elements 6 . 6 ' ,

In the 2 becomes the output signal AM (t) after the digital / analog converter 10 tapped, possibly interprocessed (not shown), to an analog / digital converter 13 handed over and transformed the folding elements 6 . 6 ' to hand over. The further verification, such as quotient calculation and the test steps, are in accordance with the embodiment 1 match.

In the 3 becomes the output signal AM (t) after the analogue amplifier 11 tapped, possibly interprocessed (not shown), to an analog / digital converter 13 Passed, converted, and the folding elements 6 . 6 ' to hand over. The further verification, such as quotient calculation and the test steps, are in accordance with the embodiment 1 match.

The 4 shows a fourth embodiment. The difference of the fourth embodiment from the previous embodiments is that in the fourth embodiment, an acoustic transducer 12 is used, the output signal AM (t) to an analog / digital converter 13 passes. As acoustic transducer 12 For example, a microphone is used, as is already present in a majority of motor vehicles.

Through an acoustic transducer 12 but would also noise 14 in which, for example, conversations of the persons in the car or ambient sounds are recorded and added to the actual output signal AM (t). However, this does not hinder the subsequent convolutions since the original output signal AM (t), despite the interference signals 14 is sufficient to perform the three test steps and to be able to make a statement as to whether the output signal output AM (t) corresponds to the notice signal A (t). An advantage of the fourth embodiment is that also the quality and possible errors in the display element 7 can be detected, since such errors would lead to a corrupted output signal AM (t) by the acoustic transducer 12 would be included.

Optionally, the analog / digital converter 13 generate the output signal AM (t) at a lower sampling rate than the digital-to-analog converter 10 the output signal AM (t) converts. This would degrade the quality of the high frequency signal check. With a lower sampling rate, however, a data reduction can be achieved. The deterioration of the high-frequency signals is not serious in this embodiment, since the driver does not record high-frequency signals with the same sensitivity as medium- or low-frequency signals.

Alternatively, signals (not shown) based on the strobe signal A (t) may also be used as the comparison signal G (t). For example, it is possible that a complete indication signal A (t) should not be output and checked, but only a specific time segment or frequency segment of a notification signal A (t). It is also possible, for example, for the functionality of an entertainment system to be checked by checking the output of an entertainment signal U (t) in the same way as described above on the basis of the advisory signal A (t) instead of the advisory signal A (t). The same is possible for an assistance signal N (t).

LIST OF REFERENCE NUMBERS

1

Storage

2

amplifier element

3

mixing element

4

output unit

5

Checking unit

6, 6 '

folding member

7

Display element

8th

computing element

9

A probe

10

Digital / analog converter

11

Analog amplifier

12

acoustic transducer

13

Analog / digital converter

14

noise

15

Time-shifting element

16

switching element

17

warning element

18

processing unit

Claims (15)

Indicating device for outputting a hint, preferably in the form of an audio-acoustic signal, comprising: at least one memory (1) with at least one indication signal (A (t)), at least one processing unit (18) for generating an output signal (AM (t)) based on the strobe signal (A (t)), at least one output unit (4), for outputting the output signal (AM (t)), marked by at least one checking unit (5), comprising: - at least one folding element (6) for folding (F1) the output signal (AM (t)) with a comparison signal (G (t)), e.g. the strobe signal (A (t)), and the convolution signal (G (t + T)), e.g. the indication signal (A (t + T)), and - At least one warning element that outputs based on the results (E1, E2) of the convolutions (F1, F2) a warning signal and / or logged. Note device according to Claim 1 , characterized in that the checking unit (5) comprises at least one calculating element (8) which calculates a quotient (Q) between the result (E1) of the first convolution (F1) and the result (E2) of the second convolution (F2). Note device according to Claim 1 or 2 , especially after Claim 2 , characterized in that the checking unit (5) is adapted to then issue no warning signal and / or to log if a) the quotient (Q) is greater than a first threshold value (S1), eg Q> S1, and / or b ) the result (E1) of the first convolution (F1) is greater than a second threshold value (S2), eg S2 <E1, and / or c) the result (E1) of the first convolution (F1) is less than a third threshold value (S3) , eg E1 <S3. Indication device according to one of the preceding claims, characterized by at least one amplifier element (2) which amplifies the indication signal (A (t)) by a gain factor (a) and mixes the result of the amplification with a background signal (R (t)) to obtain the output signal (AM (t)), eg AM (t) = A (t) * a + R (t), wherein the gain factor (a) is preferably determined based on a speed and / or a loudness. Indication device according to one of the preceding claims, characterized in that the comparison signal (G (t)) is not identical to the output signal (AM (t)), wherein a correlation factor p is at least 5% smaller than 1 and at least 5% larger than - 1 is. Information device according to one of the preceding claims, in particular according to Claim 5 , characterized in that the correlation factor p is greater than 0.5, in particular greater than 0.7. Indication device according to one of the preceding claims, characterized in that the processing unit (18) has at least one mixing element (3), the output signal (AM (t)) or the indication signal (A (t)) with at least one entertainment signal (U (t )), for example a radio playback signal and / or an assistance signal (N (t)), for example a driver assistance system output, mixes. Indication device according to one of the preceding claims, characterized by a receiving element (12), in particular a microphone, which receives the output signal (AM (t)), and an analog / digital converter (13), which outputs the output signal (AM (t) ) and transfers to the checking unit (5). Indication device according to one of the preceding claims, characterized in that the analog / digital converter (13) samples the recorded output signal at a sampling rate which is less than a sampling rate of the comparison signal (G (t)) and / or the indication signal (A (t )). Vehicle, in particular motor vehicle, with at least one hint device according to one of the preceding claims. Method for checking the function of an information device that issues an indication, in particular an information device according to one of the preceding Claims 1 to 9 the method comprising the steps of: - detecting an output signal (AM (t)) of the pointing device, - reading a comparison signal (G (t)), - first folding (F1) the output signal (AM (t)) with the comparison signal ( G (t)), eg an indication signal (A (t)), - second convolution (F2) of the output signal (AM (t)) with the comparison signal (G (t + T)) offset by an offset time (T), and Outputting a warning signal and / or logging the warning signal based on results (E1, E2) of the convolutions (F1, F2). Method according to Claim 11 , characterized by forming a quotient (Q) between the result (E1) of the first convolution (F1) and the result (E2) of the second convolution (F2). Method according to Claim 11 or 12 , especially after Claim 12 , characterized by - comparing the quotient (Q) in a first test step with a first threshold value (S1), and - comparing, in a second test step, a second threshold value (S2) with the result (E1) of the first convolution (F1) , and - comparing, in a third test step, the result (E1) of the first convolution (F1) with a third threshold value (S3), and - outputting a warning signal and / or logging if a) the quotient (Q) is smaller than that first threshold value (S1), and b) the result (E1) of the first convolution (F1) lies between the third and second threshold value (S3). Method according to one of the preceding Claims 11 to 13 , characterized in that a sampling rate for detecting the output signal (AM (t)) is lower than a sampling rate of the strobe signal (A (t)), in particular by at least 10% or 20% or 30% or 50%. A computer-readable medium having instructions that, when executed on one or more arithmetic units, perform a method according to any one of the preceding Claims 11 to 14 to implement.

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