Radar sensor arrangement and method for operating radar sensor arrangement

Abstract

The invention relates to a radar sensor arrangement (10), comprising at least one radar sensor (RS1); and a control device (SE) which is connected to the at least one radar sensor (RS1) and is designed to control the generation of a transmission signal of the radar sensor and the sampling of a reception signal of the radar sensor, the transmission signal being a periodically repeating and linearly frequency-modulated signal, and the sampling of the reception signal of the radar sensor being controlled by the control device (SE). The center frequency and / or the ramp slope and / or the pulse repetition rate of the transmission signal and / or the number of frequency ramps per measurement period and / or the pauses between the measurement periods can be set, and the control device is configured to control the transmission signal, a pulse-like interference occurring in the sampled received signal is detected and the frequency of the emission causing the interference is calculated.

Description

Technical Field

[0001] The invention relates to a radar sensor device and a method for operating a radar sensor device. Background Art

[0002] Radar sensors can play an important role in the increasing degree of vehicle automation, and the number of radar sensors per vehicle is expected to continue to increase. In common applications, many vehicles may already be equipped with driver assistance functions, which are implemented with the help of radar sensors. Radar sensors each emit a modulated electromagnetic wave and determine the distance and relative speed of different reflection points in the environment of the moving vehicle from the received, delayed and Doppler-shifted reflections.

[0003] Current serial sensors of different vehicles use modulations that are independent of one another and are usually not matched to one another, which simultaneously increases the probability that the signals of the radar sensors interfere due to overlapping electromagnetic waves and that the signal quality is reduced.

[0004] As the number of radar sensors in a vehicle increases, the radar sensors are operated in a coordinated manner in order to reduce interference with the radar sensors of the vehicle. To this end, the radar sensors are synchronized on the hardware side.

[0005] The application of the modulation method is mentioned in MBAlabd, B.Nuss, C.Winkler and T.Zwick, "Partial Chirp Modulation Technique for Chirp Sequence based Radar Communications", 201916th European Radar Conference (EuRAD), 2019, pp. 173-176.

[0006] EP 3 572 828 A1 describes a combined radar and communication system. Summary of the invention

[0007] The invention provides a radar sensor device according to claim 1 and a method for operating a radar sensor device according to claim 6 .

[0008] Preferred embodiments are the subject matter of the dependent claims.

[0009] Advantages of the present invention

[0010] The idea underlying the present invention is to specify a radar sensor device and a method for operating a radar sensor device, wherein the operation of sampling the radar sensor can be better selected for specific time and signal profiles. Sampling refers to the reception of a high-frequency signal transmitted by the radar sensor, which is characterized by a linear frequency modulation, i.e., a frequency ramp that varies over time. In the receiver, the signal received by the antenna system is mixed down to baseband with the transmitted signal and then sampled by means of an analog-digital converter.

[0011] According to the present invention, a radar sensor device comprises at least one radar sensor; and a control device, which is connected to the at least one radar sensor and is configured to apply a transmission signal to the radar sensor device and to execute a sampling sequence on the radar sensor device, wherein specific time segments of the transmission signal and / or of a reception signal at the radar sensor can be selected for application of the sampling sequence.

[0012] According to the present invention, a radar sensor device comprises at least one radar sensor; and a control device, which is connected to the at least one radar sensor and is configured to control the generation of a transmit signal of the radar sensor and the sampling of a receive signal of the radar sensor, wherein the transmit signal is a periodically repeated and linearly frequency modulated signal, and wherein the center frequency and / or the ramp slope and / or the pulse repetition rate and / or the number of frequency ramps per measuring cycle and / or the pauses between measuring cycles of the transmit signal can be adjusted, and the control device is configured to detect pulse-shaped interference occurring in the sampled receive signal and calculate the frequency of the emission causing the interference.

[0013] According to a preferred specific embodiment of the radar sensor device, the induced emission relates to a further radar sensor and is performed by the further radar sensor.

[0014] According to a preferred embodiment of the radar sensor device, the radar sensor device includes a reference control unit and a reference sensor, the reference sensor is configured to transmit a reference transmit signal, and the control device is connected to the radar sensor, and with the aid of the radar sensor device, the transmit signal of the radar sensor can be synchronized with a reference transmit signal of the reference sensor in terms of transmission and sampling via the control device.

[0015] According to a preferred specific embodiment of the radar sensor device, the transmission signal comprises a triangular signal.

[0016] According to a preferred specific embodiment of the radar sensor device, the reference unit, which includes the reference control unit and the reference sensor, and the further sensor unit, which includes the control device and the radar sensor, are located in different vehicles.

[0017] With the aid of a (defined) sampling sequence, the received signal of the radar sensor can be evaluated and the distance and movement of the object can be inferred. In this case, the sampling points and / or the transmission points can be advantageously selected in terms of frequency and time, for example for a defined time and frequency of the signal, for example also in terms of quantity and duration and / or the like. The change in frequency can be a frequency profile of a defined type at the selected sampling points, for example a section in which the signal slope increases (for example linearly or nonlinearly) or decreases or both in terms of frequency.

[0018] Thus, the sign of the ramp steepness (ramp direction) can be changed during sampling, or sampling can be performed when the slope of the signal is as expected. In this way, sampling can also be selected in the case of signal segments within a "linear frequency modulation" measurement period. A particular advantage lies in the simplicity of the method, which can be directly applied without affecting the subsequent signal processing. The desired signal can be predetermined and the following segment can be selected: the sampling can be performed on this segment.

[0019] The ramp direction within a measurement cycle can be selected arbitrarily, which can provide different potentials for the radar sensor. In this way, the use of triangular modulation can be realized with almost unchanged signal processing, whereby a bounce in the phase control loop is no longer required and the ramp repetition rate can be increased. By omitting the bounce, interference is reduced or the switching off of the transmitting amplifier can be omitted. In addition, synchronization of cooperative sensors can be carried out, whereby the transmission can also be coordinated wirelessly to avoid interference. In addition, communication between radar sensors can be realized when the ramp direction is selected according to the information data stream (e.g., a series of 0 and 1 symbols). This can be used to coordinate the communicating "radar sensors" and exchange information.

[0020] According to a preferred embodiment of the radar sensor device, the radar sensor device includes a reference sensor, which transmits a reference transmission signal and / or uses a reference sampling signal; and a control device, which controls the reference transmission signal and the reference sampling signal in terms of time, frequency and ramp direction.

[0021] Furthermore, the matching of the operation of a plurality of radar sensors to one another or the synchronization of the operation or sampling of the radar sensors may be improved.

[0022] According to a preferred specific embodiment of the radar sensor device, the predetermined transmission signal comprises a triangular signal, preferably as a function of the frequency of the transmission signal varying over time.

[0023] Advantageously, the transmit signal may be variable and may thus be adapted / synchronized with a reference signal and / or a reference sampling rate.

[0024] According to a preferred specific embodiment of the radar sensor device, sampling can be performed during a signal ramp with increasing frequency of the transmitted and / or received signal and / or during a signal ramp with decreasing frequency of the transmitted and / or received signal and / or the slope of the signal ramp can be selected by means of the control device.

[0025] According to a preferred specific embodiment of the radar sensor device, the radar sensor device comprises a plurality of radar sensors which can be installed in the same vehicle or in particular also in different vehicles and by means of which the transmission signal and the sampling frequency at the radar sensors can be synchronized with a reference sampling signal and with a reference transmission signal.

[0026] In addition to the synchronization, communication between the radar sensors via the air interface is possible.

[0027] According to the present invention, in a method for operating a radar sensor device system, a radar sensor device according to the present invention is provided, which includes at least one radar sensor and a reference sensor; pulse interference generated by the transmission of the reference sensor in the received signal of the radar sensor is detected and the transmission frequency of the transmission of the reference sensor is calculated; the radar sensor is controlled by means of a control device in such a way that the detected frequency of the frequency generated by the reference sensor in the received signal of the radar sensor is constant by appropriately setting modulation parameters, in particular the center frequency, ramp slope and time of the transmission.

[0028] According to a preferred specific embodiment of the method, the transmission of the radar sensor is also synchronized with the transmission of the reference sensor; the radar sensor is actuated by means of the control device in a sequence of ramp slopes which is suitable for minimizing the duration of the amplitude pulse disturbance and thus the interference.

[0029] According to a preferred specific embodiment of the method, the radar sensor is additionally actuated by means of the control device in a sequence of ramp slopes which is suitable for generating a series of amplitude pulse disturbances in the received signal of the reference sensor which transmit a notification according to a prescribed code book.

[0030] According to a preferred specific embodiment of the method, interference with the notifications on the radar sensor is also minimized in combination with the actuation of the radar sensor by means of a control device in a sequence of ramp slopes, the sequence having a suitable time offset with respect to the transmissions of the radar sensor in order to avoid or reduce interference caused by the reference sensor in the received signal of the radar sensor.

[0031] According to a preferred embodiment of the method, interference with the notifications on the radar sensor is also minimized, in particular in combination with the actuation of the radar sensor by means of a control device in a sequence of ramp slopes, the sequence having a suitable frequency offset with respect to the transmission of the reference sensor in order to avoid or reduce interference generated by the reference sensor in the received signal of the radar sensor.

[0032] According to a preferred specific embodiment of the method, the reference sensor transmits a message for coordinating the transmissions of the different radar sensors by transmitting a suitable ramp sequence after synchronization and transmission of the messages of the multiple radar sensors, wherein the control device of the radar sensors interprets the message according to a previously defined code book.

[0033] According to the present invention, in a method for operating a radar sensor device, a radar sensor device according to the present invention is provided; the radar sensor is controlled by means of a transmission signal and a sampling sequence is performed on the radar sensor, wherein certain time segments of the transmission signal and / or the reception signal are selected for application of the sampling sequence.

[0034] According to a preferred specific embodiment of the method, the ramp slope of the transmission signal and / or the reception signal and / or the sampling sequence is selected according to a specification.

[0035] According to a preferred specific embodiment of the method, the reference sensor transmits a reference transmit signal to which the second (or further) radar sensor synchronizes its own transmit signal by means of the control device.

[0036] According to a preferred embodiment of the method, the reference sensor generates a reference transmission signal and / or a reference sampling signal; the second sensor synchronizes the transmission signal of the second sensor with the reference transmission signal of the reference sensor in terms of transmission and sampling by means of a control device of the second sensor.

[0037] The proposed method is easy to implement and can be used directly in current radar sensors. Due to the existing separation between localization radio services and communications when adjusting current radar frequency bands, the method is also particularly suitable for future sensors in new frequency bands (e.g., greater than 100 GHz). This brings advantages to the own sensor due to the increased speed analysis range and also to all radar sensors used in the field due to reduced interference.

[0038] The radar sensor device may also be distinguished by the features mentioned in conjunction with the method and the advantages of the method, and vice versa.

[0039] Further features and advantages of embodiments of the invention emerge from the following description with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the following, the invention is explained in more detail with reference to exemplary embodiments illustrated in the schematic drawings.

[0041] The accompanying drawings show:

[0042] Figure 1 A schematic diagram of a signal profile of a frequency varying over time for operating a radar sensor device is shown according to a comparative exemplary embodiment and according to two exemplary embodiments of the invention;

[0043] Figure 2 A block diagram shows method steps of a method for operating a radar sensor device according to a further exemplary embodiment of the present invention.

[0044] Figure 3 Schematic diagram showing the interference signals of perfectly synchronized radar sensors and their deviations DETAILED DESCRIPTION

[0045] In the figures, the same reference signs denote identical or functionally identical elements.

[0046] Figure 1 According to a comparative exemplary embodiment and according to two exemplary embodiments of the invention, schematic diagrams of signal profiles with a frequency varying over time for operating a radar sensor system are shown.

[0047] exist Figure 1 A ramp signal (transmit signal or receive signal) of frequency f is shown as a function of time t, which corresponds to a conventional linear frequency modulation signal. In this case, sampling can usually only be performed on the branch with decreasing frequency at sampling points di.

[0048] What can be considered as prior art is that according to Figure 1 a The sawtooth-shaped "linear frequency modulation sequence" modulation method is shown. Figure 1 a shows the modulation scheme and the marked sampling points di on the rising slope of the frequency of the signal at the radar sensor. After two-dimensional sampling in the time direction and frequency direction, the distance (via time delay) and the speed (via Doppler shift) of the radar target can be determined (for example, in the case of superposition of the transmitted signal and the received signal).

[0049] and Figure 1b and 1c follow an inventive method according to which the "linear frequency modulation" modulation method can be used in an adapted form without thereby affecting the radar signal processing. Instead, the application of this modulation can be improved and further application possibilities arise, for example for synchronization or communication of radar sensors acting in a cooperative manner. A typical linear frequency modulation radar uses the generated transmission signal (frequency ramp with frequency dependence f(t)) as input signal for a mixer in the receive path at the same time (homodyne principle). After the mixer, a frequency ramp with a limit frequency f AAF The received signal is low-pass filtered by an anti-aliasing filter (AAF). It is then sampled by an A / D converter. Based on the homodyne principle, the frequency range sensitive to the reception of the signal is effectively moved with f(t).

[0050] Within a measuring cycle, the sign of a single slope of the signal at the radar sensor can be changed, in other words, a slope (or multiple slopes) can be selected on which the frequency curve of the radar transmission signal can occur in accordance with a certain sequence with a positive or negative slope, wherein pauses are also possible.

[0051] If the ramp direction is to be reversed without affecting the signal processing, the sampling of the frequency ramp must be adapted so that the sampled values ​​correspond to the instantaneous frequency of the phase of the ramp, i.e. with the same time step width of the sampling points, also in the case of a ramp with decreasing frequency, e.g. Figure 1 As shown in b.

[0052] In a system consisting of two radar sensors (reference sensor or first sensor and second sensor), the second sensor is now operated in a sequence complementary to the first sensor. That is, while the reference sensor uses a signal that increases in frequency over time, the second sensor uses a signal that decreases over time.

[0053] Both the first sensor and the second sensor detect sampled values ​​in the received signal that are influenced by interference from other sensors. Interference is generated by receiving high-frequency signals that are emitted by other sensors. Interference appears as amplitude pulse interference in the sampled received signal. This pulse interference is assigned to a certain frequency ( Figure 3 ).

[0054] In particular, the second sensor detects sampled values ​​that are disturbed (interfered) by the signal of the first sensor as an amplitude pulse disturbance. Figure 1The interfering sampled values ​​of the signal of the first sensor in the case of a "sequence of linear frequency modulation" method of a completely synchronized second sensor (which has a sequence complementary to the first sensor in terms of ramp slope) are located at the same frequency in each linear frequency modulation in the middle of the frequency span swept by the frequency ramp. In this case, the start times of the frequency ramps of the first and second sensors are synchronized.

[0055] The radar channel, i.e. the signal reflected by the object during the duration of the ramp (e.g. for a subsection of an ascending or descending ramp), can be considered to be constant in time in terms of its frequency in the baseband, and in the case of a ramp with the opposite direction, only the series of sampled values ​​needs to be reversed. This procedure has no effect on the subsequent signal processing.

[0056] Due to the lack of rebound at the beginning of the rising slope, e.g. Figure 1 In the case of a (a new sampling row is started again only with a rising ramp and the sampling value of the frequency jumps back to the minimum value of the sampling in the known method, but this jump can be omitted in the method step according to the invention), firstly the ramp repetition rate can be increased, thereby making it possible to clearly and uniquely measure the speed increase. Secondly, potential interference can also be reduced or the switching off of the transmission amplifier during the ramp return can be omitted.

[0057] In addition, according to Figure 1 c, different series of rising, falling or stationary regions of the signal can be used and follow one another, wherein in the case of such a change in the direction of the ramp, a binary coding can be understood (e.g., a rising ramp corresponds to 1, a falling ramp corresponds to 0, see code 1101). Figure 1 c) Information can be transmitted in a targeted manner using the meaning assigned to the code. It should be noted that the time for the jump back should take into account the constant ramp repetition rate.

[0058] Therefore, the coding of the slope direction in this way can also be used for the transmission of data between radar sensors. In this way, after synchronization between the first and second sensors, it is possible to identify, based on the temporal position of the pulse-shaped interference, whether the received interference signal is a rising slope or a falling slope. The pulse-shaped interference in the received signal is generated in the following way: the frequency-dependent f s1 The transmission signal of (t) is the same as the second sensor with a limit frequency f s2 (t)±f AAF,2 The signal can then be seen as a pulse-shaped interference in the sampled baseband signal. The actual frequency of the interference can be determined from the time position of the sampled values ​​and f s2 (t) is calculated.

[0059] Subsequently, a decoding can take place which corresponds to simple interference detection on the receiver side.

[0060] Pulse-shaped interference introduced by the communication can be limited to a few sample values ​​of the sampling sequence and can be corrected accordingly after decoding by means of conventional methods by suitable filtering or by replacing the disturbed sample values ​​with estimated values.

[0061] By assigning a meaning to the sequence of the coded rising and falling ramps used by the first sensor in the manner described above, it is possible to transmit optional information, based on which the coordination of the radar sensors can be improved. For example, an ID (identification) for the function performed by the radar sensor or a prioritization with respect to the frequency bands can be considered, and also a sensor type identifier, the center frequency and bandwidth used, etc. can be transmitted.

[0062] During communication, i.e., during the transmission of data between the radar sensors, the synchronization of the frequency ramp series of the two sensors can be readjusted (corrected or improved or equalized) by comparing the time point of the expected interference pulse with the actual time point of the interference pulse and using this difference as a control variable for the digital control of the signal output of the ramp series.

[0063] Figure 2 A block diagram shows method steps of a method for operating a radar sensor device according to a further exemplary embodiment of the present invention.

[0064] In a method for operating a radar sensor device, a radar sensor device according to the invention is provided S1 , the radar sensor is controlled S2 by means of a transmission signal and a sampling sequence is performed on the radar sensor, wherein specific time sections of the transmission signal and / or the reception signal are selected for use of the sampling sequence.

[0065] Figure 3 Schematic diagram showing interference signals of completely synchronized radar sensors and their deviations.

[0066] The method can be used for synchronization of cooperating radar sensors. In this context, "cooperation" can mean that the radar sensors are connected to one another in a certain way and / or that their operating principles are adapted to one another. For this purpose, a fixed bit sequence of a reference sensor and a transmission signal and / or a sampling signal can be determined in advance, wherein the reference sensor transmits and measures with this sequence known to all other sensors. The radar sensors to be synchronized use an inversion code, for example for the Figure 1 In the case of c, it is 0100.

[0067] In the case of perfect synchronization of the measuring cycles, a pulse-shaped interference Int can occur in the center of all ramps or baseband signals, which Figure 3 a. The frequency constant line Int shows that this pulse-like interference occurs at the same point (time or frequency connected by the ramp function) in all the ramps of the second sensor. This "same point" is advantageously located in the center of the second signal's own ramp. Complete synchronization in terms of time and frequency is then achieved. Advantageously, the ramps of the first sensor and the second sensor intersect orthogonally as increments to one another, which corresponds to complete synchronization. In the event of deviations (e.g. Figure 3 b), i.e. the inclination of the ramps away from a course that is orthogonal to one another), a correction of the ramps can take place and thus synchronization can take place.

[0068] If the interference is distributed in the direction of the upper and lower edges (i.e. towards higher and lower frequency values), there is no synchronization anymore, which is Figure 3 b and can be detected with the aid of conventional detection methods for interference. For any characteristic that modifies synchronization and is related to an error (offset in the time of the signal fS2(t) or stretch in the time of the signal fS2(t)), the length of the deviated pulse from the interference signal can be symbolic. The offset band (Balken) in the signal Int can show the frequency position of the pulse-shaped interference that has occurred, in which case the pulse-shaped interference is not synchronized. The width of each interference pulse can be a measure of the slope of the ramp for the interference signal. This feature can also be used to classify the expected pulse series of the sensor to be synchronized, from which the order of the rising and falling ramps of the first sensor can be estimated. If the deviation of the interference maximum is identified as a regulation difference (when the band Int is offset from the horizontal center), the synchronization becomes a simple regulation task. If interference only occurs occasionally, the measurement cycles have not yet overlapped and it is necessary to restore rough synchronization, for example by delay.

[0069] For synchronization, the sensor to be synchronized switches to the original code (of the second sensor), that is, the code that is optimal for its own function, and takes into account additional delays, in particular predetermined deviations from the determined reference signal, so that the sensors can always transmit in a relative pause and do not interfere with each other. After synchronization, the second sensor (for example, a control device of the second sensor) can know when the first sensor is not transmitting and can arrange in a targeted manner in this pause, where the second sensor can select the sequence of the rising and falling ramps in such a way that it is optimal for the measurement task of the second sensor.

[0070] For example, in the case of two sensors, sawtooth modulation can be used for synchronization (1111 and 0000). By shifting the temporal interference pulses away from each other (or crossing the signals in the time-frequency diagram if they are superimposed on each other), deviations can be better detected in the case of alternating ramp directions. The ramps between the reference sensor and the radar sensor can be always equalized by inserting additional pauses in the ramp sequence. In addition, for the synchronization of multiple sensors, different codes can be used for the sensors to be synchronized.

[0071] The robustness of the described method can be increased by suppressing interference signals which do not originate from the sensor to be synchronized.

[0072] By determining the interference signals and carrying out a corresponding classification according to the signal strength, the interference signals can be assigned to the individual sensors. For this purpose, advantageously, only interference signals with sufficiently similar amplitudes are used in each case.

[0073] For signal filtering, the correlation of the interference pulse train with the expected coding (eg by a priori knowledge from a so-called code book which specifies the used codes of the communicating / cooperating sensors) can be used to filter out only the pulses desired for synchronization.

[0074] Based on the homodyne principle, the width of the individual interference pulses can be a measure of the slope of the ramp of the signal used for interference, because the more similar the slopes of the frequency ramps of the first sensor are, the wider the interference pulses generated by the frequency ramps of the first sensor on the second sensor. Advantageously, this feature can be used to classify the expected pulse series of the sensor to be synchronized.

[0075] Although the invention has been completely described above on the basis of preferred exemplary embodiments, it is not restricted thereto but can be modified in an advantageous manner.

Claims

1. A radar sensor device (10), comprising: - at least one radar sensor (RS1); and - A control device (SE) which is connected to the at least one radar sensor (RS1) and is designed to control the generation of a transmit signal of the radar sensor and the sampling of a receive signal of the radar sensor, wherein the transmit signal is a periodically repeated and linearly frequency modulated signal, and wherein the center frequency and / or the ramp slope and / or the pulse repetition rate and / or the number of frequency ramps per measuring cycle and / or the pauses between measuring cycles of the transmit signal can be adjusted, and the control device is designed to detect pulse-shaped interferences occurring in the sampled receive signal and to calculate the frequency of the emission causing the interference.

2. The radar sensor device (10) according to claim 1, wherein: The induced emission relates to the other radar sensor and is performed by the other radar sensor.

3. The radar sensor device (10) according to claim 1 or 2, comprising a reference control unit (SE ref ) and a reference sensor (Ref), the reference sensor (Ref) being configured to transmit a reference transmission signal, and the control device (SE1) being connected to the radar sensor (RS1), by means of which the transmission signal of the radar sensor (RS1) can be synchronized with the reference transmission signal of the reference sensor in terms of transmission and sampling via the control device (SE1).

4. The radar sensor device (10) according to claim 1, 2 or 3, wherein: The transmission signal includes a triangular signal.

5. The radar sensor device (10) according to claim 3, wherein: The reference control unit (SE ref ) and the reference unit (SE) of the reference sensor (Ref) ref and Ref) and a further sensor unit comprising the control device (SE) and the radar sensor (RS1) are located in different vehicles.

6. A method for operating a radar sensor device system (10), the method comprising the following steps: - providing (S1) a radar sensor device (10) according to any one of claims 1 to 5, the radar sensor device comprising at least one radar sensor (RS1) and a reference sensor (Ref); - detecting (S2) pulse interferences generated in the received signal of the radar sensor (RS1) by the transmission of the reference sensor (Ref) and calculating the transmission frequency of the transmission of the reference sensor (Ref); - the radar sensor (RS1) is controlled by means of the control device (SE1) in such a way that, by suitably setting modulation parameters, in particular the center frequency of the transmission, the ramp slope and the time point, the detected frequency of the frequency generated by a reference sensor (Ref) in the received signal of the radar sensor (RS1) is constant.

7. The method according to claim 6, wherein: Additionally perform the following steps: - synchronizing the transmission of the radar sensor (RS1) with the transmission of the reference sensor (Ref); The radar sensor (RS1) is actuated by means of the control device (SE1) in a sequence of ramp slopes which is suitable for minimizing the duration of amplitude pulse disturbances and thus interference.

8. The method according to claim 6 or 7, wherein: Additionally perform the following steps: - the radar sensor (RS1) is actuated by means of the control device (SE1) in a sequence of ramp slopes which is suitable for generating a series of amplitude pulse disturbances in the received signal of the reference sensor, which series transmit a message according to a prescribed code book.

9. The method according to claim 8, wherein: Additionally perform the following steps: - In combination with the control of the radar sensor (RS1) by means of the control device (SE1) in a sequence with a ramp slope, the interference of the notification on the radar sensor (RS1) is minimized, the sequence having a suitable time offset with respect to the transmission of the radar sensor (Ref) in order to avoid or reduce interference caused by a reference sensor (Ref) in the received signal of the radar sensor (RS1).

10. The method according to claim 8 or 9, wherein: Additionally carry out the following steps:- In particular, interference of the notification on the radar sensor (RS1) is minimized in combination with the control of the radar sensor (RS1) with the aid of a ramp slope sequence with a suitable frequency offset from the emission of the reference sensor (Ref) in order to avoid or reduce interference generated by the reference sensor (Ref) in the received signal of the radar sensor (RS1).

11. The method according to any one of claims 8 to 10, wherein: After synchronization and transmission of the information of a plurality of radar sensors (RS1, RS2, RS3), the reference sensor transmits information for coordinating the transmissions of the different radar sensors by transmitting a suitable ramp sequence, wherein the control device of the radar sensors interprets the information according to a previously defined code book.

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