Method for reducing crosstalk occurrence, computer program, storage medium, electronic controller and radar sensor

Abstract

The invention relates to a method for reducing the occurrence of crosstalk during operation of a radar sensor, which has at least two transmission channels and at least one reception channel, carried out using Doppler division multiplexing modulation. In order to improve the performance capabilities of the radar sensor and the signal evaluation process implemented in this way, all transmission channel-specific phase settings between successive chirps of a transmission signal are modified simultaneously with additive terms common to the transmission channels, additive terms contained in a received signal are cancelled prior to FFT analysis of the received signal.

Description

Technical Field

[0001] The invention relates to a method for reducing crosstalk occurring during operation of a radar sensor using Doppler division multiplexing modulation, the radar sensor having at least two transmission channels and at least one reception channel. Background Art

[0002] Radar sensors are used for distance measurement, angle measurement and / or speed measurement. They are used in the automotive field, for example in driver assistance functions such as adaptive cruise control, in safety functions such as emergency brake assistance or in autonomous driving. The radar sensor transmits a high-frequency radar signal through an antenna structure and receives the radar signal reflected on the object, wherein the object can be stationary or moving. The distance and direction (angle) relative to the object can be calculated from the received radar radiation. In addition, the relative speed of the object relative to the radar sensor can be obtained from the received radar signal. For this purpose, the transmitted signal and the received signal are analyzed and processed together, especially when the Doppler shift obtained is taken into account. The key advantage of the radar sensor is the direct measurement of the physical parameter, so that the interpretation of the image, such as the image of a video camera, is not required. Typical radar sensors mostly operate in the frequency range between 76 GHz and 81 GHz.

[0003] The transmitted radar signal is usually modulated, for example by means of Doppler division multiplexing (DDM modulation). This is known, for example, from DE 10 2019 124 850 B4. A transmitter phase shifter is used here to shift the phase of the transmission signal emitted by the corresponding transmission channel of the radar sensor independently or in a transmission channel-specific manner.

[0004] In practice, in the case of DDM modulation, the phase errors that are inevitably present in the transmission channel lead to crosstalk, which in particular reduces the accuracy of the ascertainment of the angle relative to the corresponding object. Summary of the invention

[0005] One object of the present invention is to improve the performance capabilities of radar sensors and the signal evaluation that is achieved thereby.

[0006] This object is achieved by a method according to the invention for reducing crosstalk during operation of a radar sensor having at least two transmission channels and at least one reception channel using Doppler division multiplexing modulation, a computer program, a storage medium, an electronic control unit and a radar sensor. Advantageous configurations are reflected in the preferred embodiments, the following description and the drawings, wherein the configurations can each represent advantageous and / or extended aspects of the invention either by themselves or in combination with at least two of these configurations.

[0007] According to the method according to the invention for reducing crosstalk occurring during operation of a radar sensor having at least two transmission channels and at least one reception channel using Doppler division multiplexing modulation, all transmission-channel-specific phase settings between successive chirps of a transmission signal are modified simultaneously by additive terms common to the transmission channels, wherein the additive terms contained in the reception signal are eliminated prior to an FFT analysis of the reception signal.

[0008] The transmission channel-specific phase settings modified according to the invention result in a variable phase error in the transmission channel, wherein a suitable selection of the additive term allows a defined configuration of the effects of the resulting phase error, i.e. the design of the crosstalk that occurs, in particular between the individual transmission channels. This makes it possible to free specific transmission channel combinations from crosstalk phenomena or, alternatively, to achieve a uniform "blurring" between the transmission channels in the Doppler dimension by randomizing the phase error. The phase error is modified in that the periodicity of the phase error is disturbed by means of the additive term, which results in an improvement in the performance or performance capability of the radar sensor or the signal evaluation process implemented therewith, in particular with regard to the determination of the angle relative to the corresponding object.

[0009] In the method according to the invention, the transmission signal is emitted by the individual transmission channels of the radar sensor in the form of a sequence of chirps that are successive and separated in time, as is conventionally known and does not require further explanation. According to the invention, each chirp of the transmission signal of the individual transmission channels is modified by means of its own additive value, which is either contained in the additive term or corresponds to the additive term. According to the invention, the elimination of the additive term from the received signal takes place before an FFT (Fast Fourier Transformation) analysis of the received signal, by means of which the cleaned received signal is evaluated together with the corresponding transmission channel-specific transmission signal.

[0010] The modification of the transmission channel-specific phase setting according to the invention can be implemented purely on the basis of software. In addition, such a modification of the transmission channel-specific phase setting can also be adaptively or periodically changed by taking into account parameters. The software-based implementation of the invention avoids the higher requirements on the phase shifters in the high-frequency components (Hochfrequenz-Baustein) of the radar sensor, which would be associated with significantly higher costs (larger chip area) and higher current consumption.

[0011] According to an advantageous embodiment, the elimination of the additive terms is performed by means of a complex-valued window function. Alternatively, the elimination of the additive terms can also be performed in another way than by means of a complex-valued window function.

[0012] According to another advantageous embodiment, the phase shift is used as an additive term. For example, the additive term can be +10° for one chirp and -10° for the subsequent chirp, so that the phase of the transmitted signal is shifted by +10° in the case of the first chirp and -10° in the case of the subsequent chirp.

[0013] According to another advantageous embodiment, the additive term is selected from the following group of functions: a noise-like sequence, a step function, a trigonometric function, a sine function. Therefore, the value of the additive term is predetermined by a sequence or a function and varies over time corresponding to the sequence or the function. The number of steps, the step length, etc. of the corresponding sequence or function can be important parameters of the additive term and can also be adapted to the corresponding application or varied.

[0014] According to another advantageous embodiment, the additive term is selected such that the crosstalk between two specific transmission channels of the at least three transmission channels is optimized, wherein the additive term can be selected as a function of the antenna arrangement and / or the evaluation algorithm of the radar sensor. If—for example for a specific antenna arrangement—a specific transmission channel combination is to have a low amount of crosstalk, for example if there is to be less crosstalk from transmission channel TX1 to transmission channel TX3 than from transmission channel TX1 to transmission channel TX2, etc., then a favorable configuration of the crosstalk between the specific transmission channels can be optimized by a correspondingly advantageous configuration of the additive term.

[0015] According to another advantageous embodiment, the additive term is selected as a function of the driving situation of the vehicle with the radar sensor, for example as a function of the detected object. For example, the additive term can be selected as a function of the vehicle's own speed.

[0016] According to another advantageous embodiment, the additive term is changed periodically. For example, the additive term can be changed from one measurement period to another.

[0017] According to another advantageous embodiment, the additive term is selected such that in the case of discrete phase shifters it does not exceed or fall below a certain number of orders. For example, the additive term can be selected such that in the case of discrete phase shifters it does not exceed more than the third order.

[0018] The computer program according to the invention is designed to execute a method according to one of the above-mentioned embodiments or a combination of at least two of these embodiments with one another.

[0019] The advantages mentioned above in connection with the method are accordingly associated with the computer program. The computer program enables the method according to the invention to be implemented in a conventional electronic control unit without having to make structural changes thereto. For this purpose, the computer program is stored on a machine-readable storage medium. By running the computer program on a conventional electronic control unit of a radar sensor, an electronic control unit is obtained that is configured to reduce crosstalk during operation of the radar sensor using Doppler division multiplexing modulation, the radar sensor having at least two transmission channels and at least one reception channel.

[0020] The above-mentioned computer program is stored on a machine-readable storage medium according to the present invention. The storage medium may be a digital data carrier external to or internal to the computer. The advantages mentioned above in conjunction with the method are correspondingly associated with the storage medium.

[0021] The electronic controller according to the invention is configured to reduce the occurrence of crosstalk during operation of a radar sensor having at least two transmission channels and at least one reception channel using Doppler division multiplexing modulation by means of a method according to one of the above configurations or a combination of at least two of these configurations. The advantages mentioned above in conjunction with the method are correspondingly associated with the storage medium. The electronic controller can be, for example, part of a radar sensor or other vehicle electronics.

[0022] The radar sensor according to the invention has a plurality of transmission channels, at least one reception channel and the above-mentioned electronic controller. The advantages mentioned above in conjunction with the method are correspondingly associated with the storage medium. In particular, the radar sensor can be a radar sensor of a vehicle and is used for distance measurement, angle measurement and / or speed measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : A diagram for an embodiment of the method according to the invention.

[0024] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. DETAILED DESCRIPTION

[0025] Figure 1 The diagram shows an exemplary embodiment of a method according to the invention for reducing crosstalk occurring during operation of a radar sensor using Doppler division multiplexing modulation, the radar sensor having at least two transmission channels and at least one reception channel.

[0026] In method step 10, all transmission channel-specific phase settings between successive chirps of a transmission signal are modified simultaneously with an additive term common to these transmission channels. A phase offset can be used as the additive term. Alternatively, the additive term can be selected from the following group of functions: noise-like sequence, step function, trigonometric function, sine function.

[0027] Alternatively or additionally, the additive quantity can be selected such that the crosstalk between two specific transmission channels of the at least three transmission channels is optimized, wherein the additive term can be selected as a function of the antenna arrangement and / or the evaluation algorithm of the radar sensor. Alternatively or additionally, the additive term can be selected as a function of the driving situation of the vehicle with the radar sensor. Alternatively or additionally, the additive term can be changed periodically. Alternatively or additionally, the additive term is selected such that in the case of discrete phase shifters, the additive term does not exceed or fall below a specific number of orders.

[0028] After transmitting the transmission signal by means of the individual transmission channels of the radar sensor and after receiving the corresponding reception signal by means of the reception channels of the radar sensor, the additive terms contained in the reception signal are eliminated before the FFT analysis of the reception signal in method step 20. The elimination of the additive terms can be performed by means of a complex-valued window function.

[0029] Finally, the received signal cleaned by this elimination is fed to an FFT analysis, in particular in order to be able to carry out a distance measurement, an angle measurement and / or a (relative) speed measurement.

[0030] Reference Mark List

[0031] 10 Method steps (modification)

[0032] 20 Method Steps (Eliminate)

Claims

1. A method for reducing crosstalk occurring during operation of a radar sensor using Doppler division multiplexing modulation, the radar sensor having at least two transmission channels and at least one reception channel, It is characterized in that All transmit-channel-specific phase settings between successive chirps of the transmit signal are modified simultaneously by an additive term common to these transmit channels, and the additive term contained in the receive signal is eliminated before the FFT analysis of the receive signal.

2. The method according to claim 1, characterized in that The elimination of additive terms is performed with the aid of a complex-valued window function.

3. The method according to claim 1 or 2, characterized in that: The phase shift is used as an additive term.

4. The method according to claim 1 or 2, characterized in that: The additive term is selected from the following function group: a noise-like sequence, a step function, a trigonometric function, and a sine function.

5. The method according to any one of claims 1 to 4, characterized in that The additive term is selected such that the crosstalk between two specific transmission channels of the at least three transmission channels is optimized, wherein the additive term may be selected as a function of the antenna arrangement and / or the evaluation algorithm of the radar sensor.

6. The method according to any one of claims 1 to 5, characterized in that The additive term is selected depending on the driving situation of the vehicle having the radar sensor, for example depending on the detected object.

7. The method according to any one of claims 1 to 6, characterized in that The additive term changes periodically.

8. The method according to any one of claims 1 to 7, characterized in that The additive term is selected such that, in the case of a discrete phase shifter, it does not exceed or fall below a certain number of orders.

9. A computer program configured to perform the method according to any one of claims 1 to 8.

10. A machine-readable storage medium having stored thereon the computer program according to claim 9.

11. An electronic control unit configured to reduce crosstalk occurring during operation of a radar sensor using Doppler division multiplexing modulation by means of a method according to any one of claims 1 to 8, the radar sensor having at least two transmission channels and at least one reception channel. 12 . A radar sensor having a plurality of transmission channels, at least one reception channel and an electronic control unit according to claim 11 .

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