Phase difference compensation method, device and vehicle-mounted millimeter wave radar system

Abstract

The present invention discloses a phase difference compensation method, device and vehicle-mounted millimeter wave radar system, wherein the phase difference compensation method is used for TDMA-MIMO FMCW radar, and the method includes: obtaining the echo signal of each sweep cycle received by the virtual antenna array of the radar; mixing the radar's transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal contains the target distance, radial velocity and phase information of the receiving antenna; according to the intermediate frequency signal, obtain the speed influence parameter; according to the speed influence parameter, compensate the intermediate frequency signal of the corresponding sweep cycle to remove the influence of the speed on the distance and phase; according to the intermediate frequency signal of each swept cycle after compensation, calculate the phase difference of the intermediate frequency signal waveform of each swept cycle after compensation. Through the present invention, the time influence of the range-doppler spectrum transmitted in time-sharing can be supplemented from the time domain, thereby supplementing the phase influence caused by MIMO time-sharing.

Description

Technical Field

[0001] The present invention relates to the field of radar, and in particular to a phase difference compensation method, device and a vehicle-mounted millimeter wave radar system. Background Art

[0002] 77GHz millimeter wave radar sensor is an important component of autonomous driving sensors. At present, the millimeter wave radar frequency scanning method is mostly realized by linear frequency modulation continuous wave (FMCW) fast scanning, and the millimeter wave radar is used to measure speed, distance and angle. Among them, Chirp-sequence is the most commonly used wave transmission method (such as Figure 1 As shown in Figure 2, T is the transmission time of a single chirp of the linear frequency modulated wave (FMCW) (fast time), the sweep period is the time of a quick shot (such as continuous transmission of 32, 64 or 128 chirps) (slow time), and a complete set of transmissions is a beam, that is, a complete sweep period. The sampling frequency of the slow time can be changed by adjusting the order of the transmitting units, but the essence of the signal processing is the same.

[0003] In FMCW, speed and distance are measured from the results of 2D-FFT, and angle measurement is achieved through the phase difference of the receiving antenna (array antenna).

[0004] In order to increase the angular resolution of the radar, MIMO is used to increase the antenna aperture. The transmitting antenna transmits in sequence in a time-sharing manner, and each transmission doubles the number of receiving antennas. Figure 2 As shown in the figure, in the TDMA-MIMO method, the phases of the first four antenna arrays and the last four antenna arrays are not only related to the azimuth angle of the target, but also to the Doppler speed of the target.

[0005] However, if the interval between chirps is too long or the speed is too high, beam1 and beam2 are N sweeps apart, such as Figure 1 When the next antenna is transmitting, the target not only has a phase change, but also has a range change. At this time, it is difficult to get an accurate result by compensating the phase using the above formula. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a phase difference compensation method, device and vehicle-mounted millimeter wave radar system, which compensates the time influence of the time-sharing transmitted range-Doppler spectrum from the time domain, thereby compensating the phase influence caused by MIMO time-sharing.

[0007] Specifically, the technical solution of the present invention is as follows:

[0008] On the one hand, the present application discloses a phase difference compensation method, which is applied to TDMA-MIMO FMCW radar. The phase difference compensation method includes:

[0009] Acquire an echo signal of each frequency sweep cycle received by the virtual antenna array of the radar; one frequency sweep cycle includes N frequency sweeps;

[0010] Mixing the radar's transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal includes target distance, radial velocity and phase information of the receiving antenna;

[0011] According to the intermediate frequency signal, obtaining speed influencing parameters;

[0012] According to the speed influence parameter, the intermediate frequency signal of the corresponding frequency sweep period is compensated to remove the influence of speed on distance and phase;

[0013] According to the compensated intermediate frequency signal of each frequency sweeping period, the phase difference of the intermediate frequency signal waveform of each frequency sweeping period after compensation is calculated.

[0014] Preferably, the echo signal is a chirp signal, and the intermediate frequency signal corresponding to each chirp signal is expressed as follows:

[0015]

[0016] Among them, R n =R0+v*n*T;

[0017] c is the speed of light; f c0 is the center frequency; R0 is the target distance; R n is the distance of the target at the nth frequency sweep; j is a complex number; N is the number of frequency sweeps contained in a frequency sweep cycle, T is the time of a single frequency sweep; B is the frequency sweep bandwidth; v is the radial velocity;

[0018] The speed influencing parameters include a first speed influencing parameter and a second speed influencing parameter; wherein:

[0019] The first speed influencing parameter is

[0020] The second speed influencing parameter is

[0021] Preferably, the method of compensating the intermediate frequency signal of each frequency sweep cycle according to the speed influence parameter to remove the influence of speed on distance and phase specifically includes:

[0022] The conjugate of the first speed influencing parameter and the second speed influencing parameter is compensated to the time domain signal of the intermediate frequency signal; the conjugate of the first speed influencing parameter and the second speed influencing parameter is:

[0023] Perform 2D-FFT on the compensated signal, and the phase difference of the peak point in each beam spectrum is

[0024]

[0025] Where i is the index number of the beam, and the value of i is generally a positive integer greater than 1.

[0026] Preferably, the phase difference between the beams after compensation is consistent with the theoretical phase difference, and the phase difference between the beams after compensation is as follows:

[0027]

[0028] Preferably, the phase difference compensation method further includes:

[0029] Obtaining phase information of the virtual antenna array of the radar according to the compensated phase difference information; the phase information is independent of the radial velocity;

[0030] Acquire the phase relationship between each virtual receiving antenna array element according to the phase information of the virtual antenna array;

[0031] The azimuth of the detected target is calculated based on the phase relationship between the virtual receiving antenna array elements.

[0032] On the other hand, the present application also discloses a phase difference compensation device, which is applied to TDMA-MIMO FMCW radar, and the phase difference compensation device includes:

[0033] An echo acquisition module, used to acquire the echo signal of each frequency sweep cycle received by the virtual antenna array of the radar; one frequency sweep cycle includes N frequency sweeps;

[0034] A mixing processing module, used for mixing the radar's transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal contains target distance, radial velocity and phase information of the receiving antenna;

[0035] A calculation and processing module, used for obtaining speed influencing parameters according to the intermediate frequency signal;

[0036] A signal compensation module, used to compensate the intermediate frequency signal of each frequency sweep cycle according to the speed influence parameter, and remove the influence of speed on distance and phase;

[0037] The calculation and processing module is further used to calculate the phase difference of the intermediate frequency signal waveform of each frequency sweeping period after compensation according to the intermediate frequency signal of each frequency sweeping period after compensation.

[0038] Preferably, the echo signal is a chirp signal, and the intermediate frequency signal corresponding to each chirp signal is expressed as follows:

[0039]

[0040] Among them, R n =R0+v*n*T;

[0041] c is the speed of light; f c0 is the center frequency; R0 is the target distance; R n is the distance of the target at the nth frequency sweep; j is a complex number; N is the number of frequency sweeps contained in a frequency sweep cycle, T is the time of a single frequency sweep; B is the frequency sweep bandwidth; v is the radial velocity;

[0042] The speed influencing parameters include a first speed influencing parameter and a second speed influencing parameter; wherein:

[0043] The first speed influencing parameter is

[0044] The second speed influencing parameter is

[0045] Preferably, the signal compensation module specifically includes:

[0046] A conjugate compensation submodule is used to compensate the conjugate of the first speed influencing parameter and the second speed influencing parameter to the time domain signal of the intermediate frequency signal; the conjugate of the first speed influencing parameter and the second speed influencing parameter is:

[0047] The transformation calculation submodule is used to perform 2D-FFT on the compensated signal. The phase difference of the peak point in each beam spectrum is

[0048]

[0049] Where i>1 and is the number of beams.

[0050] Preferably, the phase difference between the beams after compensation is consistent with the theoretical phase difference, and the phase difference between the beams after compensation is as follows:

[0051]

[0052] On the other hand, the present application also discloses a vehicle-mounted millimeter wave radar system, comprising: the phase difference compensation device described in any one of the above items, and a TDMA-MIMO FMCW radar.

[0053] This application compensates for the distance gate-related parameters in the intermediate frequency signal based on the speed influence parameters, eliminating the influence of speed on distance and phase. After removing the gate and phase shift caused by the speed influence, the phase shift is returned to the phase of the first received signal, and the phase calculated after compensation is no longer affected by speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The preferred implementation modes will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present invention.

[0055] Figure 1 This is a schematic diagram of the Chirp-sequence wave generation method commonly used in the prior art;

[0056] Figure 2 It is a schematic diagram of MIMO radar transmission and reception in the prior art;

[0057] Figure 3 It is a flow chart of an embodiment of a phase difference compensation method of the present invention applied to TDMA-MIMO FMCW radar;

[0058] Figure 4 is a schematic diagram of a virtual receiving antenna in a simulation embodiment;

[0059] Figure 5 This is a schematic diagram of spectrum simulation before compensation;

[0060] Figure 6 This is a schematic diagram of spectrum simulation after compensation;

[0061] Figure 7 Schematic diagram of the phase difference between beams before compensation;

[0062] Figure 8 Schematic diagram of the phase difference between beams after compensation;

[0063] Fig. 9 It is a structural connection diagram of an embodiment of the phase difference compensation device of the present invention. DETAILED DESCRIPTION

[0064] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0065] In order to simplify the drawings, only the parts related to the invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0066] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0067] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0069] In the existing field of automotive millimeter-wave radar, MIMO (Multiple Input Multiple Output) technology is a key technology. Compared with single-input multiple-output radar, MIMO radar can use a smaller-scale antenna array to achieve a larger-caliber virtual antenna array, thereby improving the radar's angular resolution. FMCW radar (Frequency Modulated Continuous Wave) radar has the characteristics of low cost, simple structure, and small size. At the same time, it can accurately measure the distance and speed of the target. Combined with the application of antenna arrays, it can achieve angle measurement of the target. Frequency modulated continuous wave MIMO radar combines the advantages of the above two radars and uses a simpler antenna array to achieve higher radar angular resolution.

[0070] Existing technologies mostly use TDMA or DDMA (Doppler Division) methods to solve MIMO technology. As long as TDMA is used, the phase change caused by the relative speed between the target and the radar sensor will be affected, so we propose a new method that can compensate for the problems caused by this MIMO technology. Although DDMA technology can solve the problem of time difference in multiple snapshot technologies, this technology can only ensure that a small number of transmitting units are transmitted at the same time. In today's high-performance millimeter-wave radar technology, the number of transmitting units is large (usually reaching 12, 24 or 48 or more), so the time-division transmission method is basically unavoidable even when using DDMA or other MIMO methods.

[0071] TDMA-MIMO FMCW (Time Division Multiplexing-Multiple Multiple InputMultiple Output Frequency Modulated Continuous Wave) radar is a frequency modulated continuous wave MIMO radar that uses time division multiplexing technology to achieve orthogonal transmission waveforms. In this radar, the transmission and reception of signals are controlled by specific time division multiplexing timing. However, the disadvantage of this method is that the phase of the received signal of the virtual antenna array is not only determined by the angle of the target, but also related to the target speed. In addition, the relative speed of the target not only affects the change of phase, but also causes distance deviation. At this time, the theoretical compensation phase (theoretical compensation phase formula: )It is difficult to get accurate results.

[0072] Based on this, refer to the attached manual Figure 3 The present invention provides a phase difference compensation method, which is applied to TDMA-MIMOFMCW radar. The phase difference compensation method includes:

[0073] S101, obtaining an echo signal of each frequency sweep cycle received by the virtual antenna array of the radar; one frequency sweep cycle includes N frequency sweeps;

[0074] Specifically, the radar refers to a TDMA-MIMO FMCW radar, and the radar is set to have P transmitting antennas and Q receiving antennas, and its corresponding virtual antenna array is a uniform linear array, and has PQ antenna elements. The radar sets the time division multiplexing timing of the transmitting antenna and the receiving antenna, so that the virtual antenna array obtains the echo signal after each frequency sweep in the order of the 1st element, the 2nd element, the 3rd element, ..., the PQth antenna element, and a frequency sweep cycle includes N frequency sweeps. The radar usually uses fast chirp as the transmitting signal. Fast chirp signals usually refer to frequency modulated continuous wave signals with small width and large bandwidth. Through the time division multiplexing timing of the transmitting antenna element and the receiving antenna element, the virtual antenna array receives the reflected echo signal according to a specific time division multiplexing timing.

[0075] S102, mixing the radar transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal includes target distance, radial velocity and phase information of a receiving antenna;

[0076] Specifically, the echo signal is amplified by a low-noise amplifier and mixed with the local oscillator signal (part of the transmitted signal) in a mixer to output an intermediate frequency signal (or difference frequency signal). The intermediate frequency signal contains information such as the distance and relative speed between the target and the radar, and the phase of the receiving antenna.

[0077] S103, obtaining a speed influencing parameter according to the intermediate frequency signal;

[0078] Specifically, since the relative speed between the target and the radar will affect the phase and the distance, it is necessary to obtain the influencing parameters introduced by the relative speed (i.e., speed influencing parameters). The intermediate frequency signal contains radial speed information, so the speed influencing parameters can be calculated.

[0079] S104, compensating the intermediate frequency signal of each frequency sweep cycle according to the speed influence parameter to remove the influence of speed on distance and phase;

[0080] Specifically, after the speed influence parameter is obtained, the relevant part of the intermediate frequency signal in each frequency sweep cycle is compensated to eliminate the influence of the relative speed on the distance and phase.

[0081] S105, calculating the phase difference of the intermediate frequency signal waveform of each frequency sweep period after compensation according to the intermediate frequency signal of each frequency sweep period after compensation.

[0082] Specifically, after eliminating the influence of speed on the phase, the phase between beams corresponds to the theoretical phase. Then, the phase difference between the compensated receiving antennas can be calculated. A sweep cycle can be regarded as a beam. By compensating the theoretical phase, the speed-independent phase information is obtained, and then the angle can be calculated by the phase relationship between channels. A complete set of transmissions is a beam, that is, each beam can be regarded as a complete sweep cycle.

[0083] In another embodiment of the present application, based on the above embodiment, the intermediate frequency signal includes target distance, radial velocity and antenna phase information. The echo signal is a chirp signal, and the intermediate frequency signal corresponding to each chirp signal is expressed as follows:

[0084]

[0085] Among them, R n =R0+v*n*T;

[0086] c is the speed of light; f c0 is the center frequency; R0 is the target distance; R n is the distance of the target at the nth frequency sweep; j is a complex number; N is the number of frequency sweeps, T is the time of a single frequency sweep; B is the frequency sweep bandwidth; v is the radial velocity; n is the nth frequency sweep; and t is the sampling time point.

[0087] R n Expanded, the expanded intermediate frequency signal is expressed as follows:

[0088]

[0089] Among them, the parameters related to the distance traveled, namely the speed influencing parameters, include the first speed influencing parameter The second speed affects the parameters Two parts.

[0090] The two parts are compensated in the intermediate frequency signal to eliminate the influence of speed on distance and phase. Specifically, the conjugate of the first speed influencing parameter and the second speed influencing parameter is compensated to the time domain signal of the intermediate frequency signal; the conjugate of the first speed influencing parameter and the second speed influencing parameter is:

[0091]

[0092] Perform 2D-FFT on the compensated signal, and the phase difference of the peak point in each beam spectrum is:

[0093]

[0094] Where i is the index of the beam, for example, beam3, then i=3; c is the speed of light; f c0 is the center frequency; R0 is the target distance; n is the number of sweeps; j is a complex number; N is the number of sweeps, T is the time of a single sweep; B is the sweep bandwidth; v is the radial velocity.

[0095] Therefore, if the gate and phase shift caused by the speed influence are removed, the phase shift will return to the phase of the first received signal, eliminating the influence of speed on the phase.

[0096] After eliminating the phase effect, the phase between beams corresponds to the theoretical phase:

[0097]

[0098] At this time, the speed-independent phase information can be obtained by compensating the theoretical phase, and then the angle can be calculated through the phase relationship between the channels.

[0099] The following is a description of the specific simulation example. The radar parameters set in the simulation are as follows:

[0100] Sweep mode: FMCW; Center frequency: 76.5GHz; Sweep bandwidth: 400MHz;

[0101] Speed ​​range v = [-200km / h ~ 400km / h]; Number of transmitting antennas: 3, Number of beams: 3;

[0102] Beam transmission time: [0, 128*T, 256T]; receiving channels: 4; virtual receiving antennas such as Figure 4 shown.

[0103] In order to see more obvious results on the spectrum in 2D-FFT, we choose -800km / h simulation.

[0104] Compensation comparison results are as follows Figure 5 , 6 As shown, Figure 5 This is the spectrum simulation diagram before compensation; Figure 6 This is the spectrum simulation diagram after compensation; Figure 5 and Figure 6 The first row is the 2d-FFT result of beam1, and the second row is the 2d-FFT result of beam3. By comparing before and after compensation, we can clearly see that the distance deviation has been compensated.

[0105] Figure 7 and Figure 8 They are the phase difference between the beams before and after compensation. In this example, the phase of the receiving antenna channels at four different positions is plotted at the same time. Figure 7 and Figure 8 In the figure, the horizontal axis is the relative velocity Vd (ie, radial velocity v), and the vertical axis is the phase difference. Specifically, the first line is the phase difference between beam1 and beam2, and the second line is the phase difference between beam1 and beam3. Figure 7 This is the result without phase compensation. Figure 8 This is the result after phase compensation. As can be seen from the figure, after compensation, the phase between beams shows the same pattern as the theoretical value. The phase offset can be compensated by the theoretical result.

[0106] Another embodiment of the method of the present invention, based on any of the above embodiments, further includes the steps of:

[0107] Obtaining phase information of the virtual antenna array of the radar according to the compensated phase difference information; the phase information is independent of the radial velocity;

[0108] Acquire the phase relationship between each virtual receiving antenna array element according to the phase information of the virtual antenna array;

[0109] The azimuth of the detected target is calculated based on the phase relationship between the virtual receiving antenna array elements.

[0110] Specifically, this embodiment can obtain speed-independent phase information through theoretical phase compensation, and then calculate the angle through the phase relationship between channels.

[0111] On the other hand, the present application also discloses a phase difference compensation device, which is applied to TDMA-MIMO FMCW radar. An embodiment of the phase difference compensation device is as follows: Fig. 9 As shown, including:

[0112] The echo acquisition module 100 is used to acquire the echo signal of each frequency sweep cycle received by the virtual antenna array of the radar; one frequency sweep cycle includes N frequency sweeps;

[0113] A mixing processing module 200 is used to mix the radar transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal contains target distance, radial velocity and phase information of the receiving antenna;

[0114] A calculation and processing module 300 is used to obtain speed influencing parameters according to the intermediate frequency signal;

[0115] A signal compensation module 400, used to compensate the intermediate frequency signal of each frequency sweep cycle according to the speed influence parameter, and remove the influence of speed on distance and phase;

[0116] The calculation processing module 300 is further used to calculate the phase difference between the intermediate frequency signal waveforms of each frequency sweeping period after compensation according to the intermediate frequency signal of each frequency sweeping period after compensation.

[0117] In one embodiment, the echo signal is a chirp signal, and the intermediate frequency signal corresponding to each chirp signal is expressed as follows:

[0118]

[0119] Among them, R n =R0+v*n*T;

[0120] c is the speed of light; f c0 is the center frequency; R0 is the target distance; R n is the distance of the target at the nth frequency sweep; n is the nth frequency sweep; j is a complex number; N is the number of frequency sweeps contained in a frequency sweep cycle, T is the time of a single frequency sweep; B is the frequency sweep bandwidth; v is the radial velocity;

[0121] R n Expand and substitute into the above intermediate frequency signal formula, we can get:

[0122]

[0123] Among them, the parameters related to the distance traveled, namely the speed influencing parameters, include: the first speed influencing parameter The second speed affects the parameters Two parts.

[0124] After obtaining the speed influence parameters, the signal compensation module compensates these two parts in the intermediate frequency signal to eliminate the influence of speed on distance and phase. These two parts are compensated in the intermediate frequency time domain signal.

[0125] Specifically, the signal compensation module specifically includes:

[0126] A conjugate compensation submodule is used to compensate the conjugate of the first speed influencing parameter and the second speed influencing parameter to the time domain signal of the intermediate frequency signal; the conjugate of the first speed influencing parameter and the second speed influencing parameter is:

[0127] The transformation calculation submodule is used to perform 2D-FFT on the compensated signal. The phase difference of the peak point in each beam spectrum is

[0128]

[0129] Where i is a positive integer greater than 1 and is the index number of the beam.

[0130] The phase difference between the beams after compensation corresponds to the theoretical phase difference. The phase difference between the beams after compensation is as follows:

[0131]

[0132] In the above formulas of this embodiment, c is the speed of light; R0 is the target distance; n is the number of sweeps; f c0 is the center frequency; j is a complex number; N is the number of sweeps, T is the time of a single sweep; B is the sweep bandwidth; v is the radial velocity.

[0133] It is worth noting that in the various formulas of the present application, the same letters represent the same meaning. In order to reduce repetition, they are not repeated one by one. Please refer to the meanings of the letters in the aforementioned formulas.

[0134] Another embodiment of the phase difference compensation device of the present application, based on any of the above device embodiments, the phase difference compensation device further includes: an azimuth acquisition module for acquiring a detection target (target object)

[0135] The azimuth acquisition module specifically includes:

[0136] A phase acquisition submodule, used to obtain phase information of the virtual antenna array of the radar according to the compensated phase difference information; the phase information is independent of the radial velocity;

[0137] The phase acquisition submodule is further used to acquire the phase relationship between each virtual receiving antenna array element according to the phase information of the virtual antenna array;

[0138] The azimuth calculation submodule is used to calculate the azimuth of the detected target according to the phase relationship between the virtual receiving antenna array elements.

[0139] The phase compensation device embodiment in the present application corresponds to the phase compensation method embodiment, and has the same technical concept. The technical information in the phase compensation method embodiment is also applicable to the phase compensation device embodiment, and will not be described in detail to reduce repetition.

[0140] Another embodiment of the present application discloses a vehicle-mounted millimeter wave radar system, comprising: the phase difference compensation device described in any one of the above embodiments, and a TDMA-MIMO FMCW radar.

[0141] Specifically, the phase difference compensation device described in any of the above embodiments is integrated in a TDMA-MIMO FMCW radar to perform signal processing, especially phase difference compensation, on the echo signal acquired by the TDMA-MIMO FMCW radar to eliminate the influence of speed on phase and distance.

[0142] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A phase difference compensation method, characterized in that: Applied to TDMA-MIMO FMCW radar, the phase difference compensation method includes: Acquire an echo signal of each frequency sweep cycle received by the virtual antenna array of the radar; one frequency sweep cycle includes N frequency sweeps; Mixing the radar's transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal includes target distance, radial velocity and phase information of the receiving antenna; According to the intermediate frequency signal, obtaining speed influencing parameters; According to the speed influence parameter, the intermediate frequency signal of the corresponding frequency sweep period is compensated to remove the influence of speed on distance and phase; According to the intermediate frequency signal of each frequency sweeping cycle after compensation, the phase difference of the intermediate frequency signal waveform of each frequency sweeping cycle after compensation is calculated; The echo signal is a chirp signal, and the intermediate frequency signal corresponding to each chirp signal is expressed as follows: Among them, R n =R0+v*n*T; c is the speed of light; f c0 is the center frequency; R0 is the target distance; R n is the distance of the target at the nth frequency sweep; j is a complex number; N is the number of frequency sweeps contained in a frequency sweep cycle, T is the time of a single frequency sweep; B is the frequency sweep bandwidth; v is the radial velocity; The speed influencing parameters include a first speed influencing parameter and a second speed influencing parameter; wherein: The first speed influencing parameter is The second speed influencing parameter is The method of compensating the intermediate frequency signal of each frequency sweep cycle according to the speed influence parameter to remove the influence of speed on distance and phase specifically includes: The conjugate of the first speed influencing parameter and the second speed influencing parameter is compensated to the time domain signal of the intermediate frequency signal; the conjugate of the first speed influencing parameter and the second speed influencing parameter is: Perform 2D-FFT on the compensated signal, and the phase difference of the peak point in each beam spectrum is Where i is the index of the beam.

2. The phase difference compensation method according to claim 1, characterized in that: The phase difference between the beams after compensation is consistent with the theoretical phase difference. The phase difference between the beams after compensation is as follows:

3. The phase difference compensation method according to any one of claims 1 to 2, characterized in that: Also includes: Obtaining phase information of the virtual antenna array of the radar according to the compensated phase difference information; the phase information is independent of the radial velocity; Acquire the phase relationship between each virtual receiving antenna array element according to the phase information of the virtual antenna array; The azimuth of the detected target is calculated based on the phase relationship between the virtual receiving antenna array elements.

4. A phase difference compensation device, characterized in that: Applied to TDMA-MIMO FMCW radar, the phase difference compensation device comprises: An echo acquisition module, used to acquire the echo signal of each frequency sweep cycle received by the virtual antenna array of the radar; one frequency sweep cycle includes N frequency sweeps; A mixing processing module, used for mixing the radar's transmission signal with the echo signal to obtain an intermediate frequency signal; the intermediate frequency signal contains target distance, radial velocity and phase information of the receiving antenna; A calculation and processing module, used for obtaining speed influencing parameters according to the intermediate frequency signal; A signal compensation module, used to compensate the intermediate frequency signal of the corresponding frequency sweep period according to the speed influence parameter, and remove the influence of speed on distance and phase; The calculation processing module is further used to calculate the phase difference of the intermediate frequency signal waveform of each frequency sweeping period after compensation according to the intermediate frequency signal of each frequency sweeping period after compensation; The echo signal is a chirp signal, and the intermediate frequency signal corresponding to each chirp signal is expressed as follows: Among them, R n =R0+v*n*T; c is the speed of light; f c0 is the center frequency; R0 is the target distance; R n is the distance of the target at the nth frequency sweep; j is a complex number; N is the number of frequency sweeps, T is the time of a single frequency sweep; B is the frequency sweep bandwidth; v is the radial velocity; The speed influencing parameters include a first speed influencing parameter and a second speed influencing parameter; wherein: The first speed influencing parameter is The second speed influencing parameter is The signal compensation module specifically includes: A conjugate compensation submodule is used to compensate the conjugate of the first speed influencing parameter and the second speed influencing parameter to the time domain signal of the intermediate frequency signal; the conjugate of the first speed influencing parameter and the second speed influencing parameter is: The transformation calculation submodule is used to perform 2D-FFT on the compensated signal. The phase difference of the peak point in each beam spectrum is Where i is the index of the beam.

5. The phase difference compensation device according to claim 4, characterized in that: The phase difference between the beams after compensation is consistent with the theoretical phase difference. The phase difference between the beams after compensation is as follows:

6. A vehicle-mounted millimeter wave radar system, characterized in that: include: The phase difference compensation device according to any one of claims 4 to 5, and a TDMA-MIMO FMCW radar.

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