A method for designing MIMO radar waveform to suppress velocity ambiguity

Abstract

The application discloses a MIMO radar waveform design method for inhibiting velocity ambiguity, comprising the following steps of: S1, inserting z de-ambiguity sequences according to frame period requirements: a MIMO radar with N t transmitting antennas and N r receiving antennas adopts a time division transmitting waveform, the transmitting antennas are sequentially turned on in the order of 1, 2, …, N t , and the N r receiving antennas simultaneously receive echo signals generated by each transmitting antenna, the starting time of the de-ambiguity sequence is separated from the ending time of the previous normal sequence by a certain delay time a; then the echo signals are mixed with corresponding transmitting signals to obtain beat signals, the ambiguity multiple is solved according to the phase difference of the beat signals of the normal sequence and the de-ambiguity sequence transmitted by the same transmitting antenna, and for each receiving antenna, one ambiguity multiple can be solved for each inserted de-ambiguity sequence; S2, solving the ambiguous velocity of a target; S3, taking the mode of the ambiguity multiple to calculate the de-ambiguous target velocity. The application can significantly improve the de-ambiguity correctness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of millimeter wave vehicle-mounted radar, and particularly relates to a MIMO radar waveform design method for suppressing velocity ambiguity. BACKGROUND

[0002] A linear frequency modulation continuous wave (LFMCW) radar measures target distance by using one-dimensional information and measures target velocity by using Doppler information. When the Doppler frequency generated by the target velocity is greater than half of the pulse repetition frequency (PRF) of the radar, Doppler ambiguity will be generated, which will lead to incorrect target velocity estimation, that is, velocity ambiguity occurs.

[0003] A conventional method for resolving velocity ambiguity is to use two frames of data with different pulse repetition frequencies, and to resolve velocity ambiguity according to the Chinese remainder theorem. This conventional method has high computational complexity, requires a high signal-to-noise ratio of the echo, and has a problem of target pairing in a multi-target case. Another method for resolving ambiguity based on phase difference information of a delay sequence has the advantages of avoiding the problem of target pairing, simple calculation, strong real-time performance, and strong applicability in vehicle-mounted radars, but only uses a conventional sequence and a delay sequence to solve the velocity ambiguity multiple, and the accuracy needs to be improved.

[0004] Considering system complexity and data processing efficiency, current vehicle-mounted MIMO radars mostly use time division transmission waveforms. Time division transmission makes the maximum unambiguous measurement velocity of the radar smaller. The present application solves the problem of low accuracy by using multiple conventional sequences and delay sequences to solve multiple ambiguity multiples on the basis of the beat signal phase difference of the conventional sequence and the delay sequence. SUMMARY

[0005] The purpose of the present application is to provide a MIMO radar waveform design method for suppressing velocity ambiguity, which solves the problems of high complexity, low accuracy, and target pairing.

[0006] To achieve the above purpose, the present application provides a MIMO radar waveform design method for suppressing velocity ambiguity, comprising the following steps:

[0007] S1, inserting z de-ambiguity sequences according to frame period requirements: a MIMO radar with N t transmit antennas and N r receive antennas uses a time division transmission waveform, and the transmit antennas are opened in turn in the order of 1, 2, …, N t , and the receive antennas are opened in turn in the order of 1, 2, …, N rEach receiving antenna simultaneously receives the echo signal generated by each transmitting antenna. z deambiguation sequences (z is a positive integer) are inserted, and the start time of the deambiguation sequence is delayed by a certain time 'a' from the end time of the previous regular sequence. The echo signal is then mixed with the corresponding transmitting signal to obtain a beat signal. The ambiguity factor is calculated based on the phase difference between the beat signals of the regular sequence and the deambiguation sequence transmitted by the same transmitting antenna. For each receiving antenna, one ambiguity factor can be calculated for each inserted deambiguation sequence.

[0008] S2. Find the fuzzy velocity of the target;

[0009] S3. Take the mode of the velocity ambiguity factor and calculate the target velocity for deambiguation.

[0010] Specifically, step S1 includes:

[0011] S11. Insert z deambiguation sequences: Transmitting antenna 1 first transmits the first linear frequency modulated (LFM) signal, which is the conventional sequence A1, with an interval delay time a, and then transmits the second LFM signal, which is the deambiguation sequence B1; Transmitting antenna 2 immediately follows the deambiguation sequence B1 and transmits the LFM signal, which is the conventional sequence A2, with an interval delay time a, and then transmits the LFM signal, which is the deambiguation sequence B2; ...; The z-th transmitting antenna immediately follows the deambiguation sequence B Z-1 Transmit a linear frequency modulated signal, which is a conventional sequence A. Z After a delay of time 'a', a linear frequency modulated signal is transmitted again to form the deambiguity sequence B. Z From transmitting antenna z+1 to transmitting antenna N t The linear frequency modulated signals are transmitted sequentially, forming a conventional sequence A. Z+1 To regular sequence

[0012] S12. Calculate the beat signal s1(n,l) of the (l+1)th period of the regular sequence A1;

[0013] S13. Calculate the beat signal s2(n,l) of the (l+1)th period of the unfuzzy sequence B1;

[0014] S14. Perform two-dimensional discrete Fourier transform (DFT) calculations on the beat signal s1(n,l) of the (l+1)th period of the conventional sequence A1 obtained in step S12 and the beat signal s2(n,l) of the (l+1)th period of the defuzzified sequence B1 obtained in step S13, respectively, to obtain S1(k,p) and S2(k,p), and then obtain the distance-velocity map.

[0015] S15. Obtain the phase of the complex signal at the peak of S1(k,p). Phase of the complex signal at the peak of S2(k,p)

[0016] S16, obtaining the number of resolvable ambiguity factors N q and the minimum value of the resolvable ambiguity factor q min and setting a reference phase;

[0017] S17, obtaining the velocity ambiguity factor of a set of range-velocity maps;

[0018] S18, repeating the steps S12 to S17 to sequentially solve the corresponding ambiguity factor q' according to the phase difference of the regular sequence A m , the de-ambiguity sequence B m , a total of z·N r ambiguity factors q', wherein m = 1, 2, …, z.

[0019] Specifically, the step S12 specifically comprises mixing the echo signal with the transmitted signal to obtain a beat signal, and the beat signal s(n) of the first cycle of the regular sequence A1 is:

[0020]

[0021] wherein j = sqrt(-1), that is, the square root of -1, n is a distance sampling point, the chirp signal is a positive frequency modulation, R is the distance of the target at the starting time of sampling, c is the speed of light, B and T are the bandwidth and frequency modulation period of the linear frequency modulation signal, N is the number of sampling points in one frequency modulation period, V r is the set target speed, f0 is the radar carrier frequency, is the beat frequency frequency generated by the coupling of distance and speed in one frequency modulation period; due to the target motion, in the l+1th cycle, the distance of the target at the starting time of sampling is R+V r Tl, and the beat signal s1(n, l) of the l+1th cycle of the regular sequence A1 is:

[0022] wherein l is the transmission cycle of the same sequence, the beat frequency change caused by the target motion is ignored, and the above formula is simplified as:

[0023] wherein is the Doppler frequency;

[0024] Let T d be the cycle of the same sequence, and T D = N t T+z(T+a), q is the ambiguity factor, then wherein f rd is the ambiguous Doppler frequency, and the above formula is written as:

[0025]

[0026] Specifically, the step S13 is specifically: according to the calculation method of the beat signal s1(n, l) of the (l+1)th period of the regular sequence A1 in the step S12, the beat signal s2(n, l) of the (l+1)th period of the deblurring sequence B1 is obtained as:

[0027]

[0028] Specifically, the calculation formula of the two-dimensional discrete Fourier transform DFT in the step S14 is:

[0029]

[0030]

[0031] Wherein, N Z , L Z are the DFT point number in the distance direction and the DFT point number in the velocity direction respectively, S1(k, p) is the two-dimensional DFT result of s1(n, l) of the beat signal A1 of the regular sequence, S2(k, p) is the two-dimensional DFT result of the beat signal s2(n, l) of the deblurring sequence B1, k is the frequency in the distance direction, and p is the Doppler frequency.

[0032] Specifically, the step S15 is specifically:

[0033]

[0034] Wherein, arg(·) is a phase taking operation, round(·) represents a rounding function, K peak is the distance direction frequency corresponding to the maximum amplitude of S1(k, p) or S2(k, p), P peak is the Doppler frequency corresponding to the maximum amplitude of S1(k, p) or S2(k, p); the phase difference variable is defined as:

[0035]

[0036] Thus, the following can be obtained:

[0037]

[0038] For the convenience of analysis, define as:

[0039]

[0040] In actual situation, due to the existence of noise, the above formula is rewritten as:

[0041] Wherein, is the phase of noise.

[0042] Specifically, step S16 is as follows:

[0043] Number of fuzzy multiples Where gcd(·) is the greatest common divisor;

[0044] Minimum value of fuzzy multiple Where % represents the remainder;

[0045] The reference phase is set as follows:

[0046] Specifically, step S18 involves: calculating the regular sequence A. m The steps for calculating the beat signal in the (l+1)th period are the same as those for calculating the beat signal in the (l+1)th period of the regular sequence A1; the steps for calculating the defuzzified sequence B are... m The steps for calculating the beat signal of the (l+1)th period are the same as those for calculating the beat signal of the (l+1)th period of the defuzzified sequence B1.

[0047] Specifically, step S2 involves obtaining one RD image from one channel, N t ·N r N channels are obtained t ·N r RD diagram, N t ·N r The range-velocity maps are incoherently superimposed. Targets are detected on the incoherently superimposed range-velocity maps to obtain the blurred velocity V of the target. amb : Among them, V res For speed resolution, T f The frame period.

[0048] Specifically, step S4 includes:

[0049] S41. Take the z·N obtained in step S1. r The mode of a fuzzy multiple q′ is used as the final fuzzy multiple q, where q = mode(q′), and mode(·) is the mode selection operation;

[0050] S42. Based on the target's fuzzy velocity V obtained in step S2... amb Using the final ambiguity factor q obtained in step S41, calculate the deambiguation target velocity V, using the following formula:

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The application solves the speed ambiguity multiple by inserting a certain number of ambiguity resolution sequences, uses the phase difference of the range-velocity graph obtained by the normal frequency modulation sequence and the ambiguity resolution sequence of the same receiving antenna to solve the ambiguity multiple, N r receiving channels, z ambiguity resolution sequences, N r ·z ambiguity multiples, take the mode of N r ·z ambiguity multiples as the final ambiguity multiple, so that the correct rate of solving the ambiguity multiple is high.

[0053] 2. The number of ambiguity resolution sequences inserted according to the frame period requirement can be flexibly set, and the mode of solving the ambiguity multiple by using multiple groups of RD graphs and taking the mode can significantly improve the ambiguity resolution correct rate.

[0054] 3. The application is suitable for target speed estimation of vehicle-mounted millimeter wave radar, and has the advantages of simple calculation and high speed ambiguity resolution correct rate. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 is the flow chart of the application;

[0056] Figure 2 is the time division MIMO radar ambiguity resolution waveform transmission sequence schematic diagram of the application;

[0057] Figure 3 is the Monte Carlo experimental simulation result comparison diagram of the application. DETAILED DESCRIPTION

[0058] The technical content, structural features, purposes achieved and effects of the application will be described in detail below by preferred embodiments in combination with the drawings.

[0059] It should be noted that the drawings are greatly simplified and all use non-precise proportions, only to facilitate and clearly assist in explaining the purpose of the embodiments of the application, and are not used to limit the limiting conditions of the implementation of the application, so they do not have substantial technical significance, any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that can be produced by the application and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the application.

[0060] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0061] This invention provides a method for designing MIMO radar waveforms to suppress velocity ambiguity. MIMO radar (Multiple Input Multiple Output) has N... t One transmit (TX) antenna, N r There are 1 receiving (RX) antenna, using time-division multiplexing (TDD) transmit waveforms (to ensure good orthogonality of the transmit waveforms), and the transmit antennas are arranged in sequence 1, 2, ..., N. t The [devices] are opened sequentially to transmit signals to the target, while N... r Each receiving antenna simultaneously receives the target echo signal generated by each transmitting antenna that is turned on sequentially, which can be equivalent to N... t ·N r The echo signals of each channel are obtained through the following steps:

[0062] S1, based on frame period T f The requirement is to insert z deambiguation sequences (z is a positive integer) between the transmitted signals, and the start time of the deambiguation sequence is separated from the end time of the previous regular sequence by a certain delay time a, where z can be 1, 2, 3, ..., N. t The echo signal is then mixed with the corresponding transmitted signal to obtain the beat signal. The ambiguity factor is calculated based on the phase difference between the beat signals of the conventional sequence and the deambiguity sequence transmitted by the same transmitting antenna. Furthermore, for each deambiguity sequence inserted, an ambiguity factor can be calculated for each receiving antenna. The specific steps include:

[0063] S11. Insert z unfuzzy sequences, such as Figure 2 As shown, specifically: Transmitting antenna 1 first transmits the first linear frequency modulated (chirp) signal (corresponding to sequence 1, a conventional sequence A1), after a delay time a, and then transmits the second chirp signal (corresponding to sequence 2, a deambiguity sequence B1); Transmitting antenna 2 immediately follows sequence 2 by transmitting a chirp signal (corresponding to sequence 3, a conventional sequence A2), after a delay time a, and then transmits a chirp signal (corresponding to sequence 4, a deambiguity sequence B2); ...; The z-th transmitting antenna immediately follows the deambiguity sequence z-1 by transmitting a chirp signal (corresponding to sequence 2z-1, a conventional sequence A1). Z), interval delay time a, re-emit chirp signal (corresponding to sequence 2z, for debunching sequence B Z ), then transmit antenna z+1 to transmit antenna N t emit chirp signal in turn (corresponding to sequence 2z+1 to sequence N t +z, for normal sequence A Z+1 to normal sequence ), then N r receive antennas can solve z·N r ambiguity times.

[0064] S12, calculate the beat signal of the l+1th period of the normal sequence, taking the normal sequence A1 as an example, specifically: first, calculate the beat signal s(n) of the 1st period of the normal sequence A1 as

[0065]

[0066] In the above formula, j=sqrt(-1) is the square root of-1, n is the distance to the sampling point, the chirp signal is positive frequency modulation, R is the distance of the target at the start of sampling, c is the speed of light, B and T are the bandwidth and frequency modulation period of the chirp signal, N is the number of sampling points in one frequency modulation period, V r is the set target speed, f0 is the radar carrier frequency, is the beat frequency frequency generated by the coupling of distance and speed in one frequency modulation period.

[0067] Due to target motion, in the l+1th period, the distance of the target at the start of sampling is R+V r Tl, then the beat signal s1(n, l) of the l+1th period of the normal sequence A1 is

[0068]

[0069] In the above formula, l is the transmission period of the same sequence, and the beat frequency change caused by target motion is ignored, and the above formula is simplified as

[0070]

[0071] In the above formula, is the Doppler frequency.

[0072] Further, let T d be the period of the same sequence, and T D =N t T+z(T+a), q is the ambiguity times, then where f rd is the ambiguous Doppler frequency, and the above formula is written as

[0073]

[0074] S13, beat signals of the l+1th period of the deblurring sequence are calculated, taking the deblurring sequence B1 as an example, referring to the calculation method of the beat signals s1(n, l) of the l+1th period of the regular sequence A1 in step S12, the beat signals of the l+1th period of the deblurring sequence B1 are obtained as s2(n, l)

[0075]

[0076] S14, the beat signals s1(n, l) of the l+1th period of the regular sequence A1 obtained in step S12 and the beat signals s2(n, l) of the l+1th period of the deblurring sequence B1 obtained in step S13 are respectively subjected to two-dimensional DFT (two-dimensional discrete Fourier transform) calculation, and a range-velocity (RD) diagram is obtained, and the two-dimensional DFT calculation formula is

[0077]

[0078]

[0079] In the above formula, N Z and L Z are the number of DFT points in the range direction and the number of DFT points in the velocity direction respectively, S1(k, p) is the two-dimensional DFT result of the beat signals s1(n, l) of the regular sequence, S2(k, p) is the two-dimensional DFT result of the beat signals s2(n, l) of the deblurring sequence, k is the frequency in the range direction, and p is the Doppler frequency, and the peak values of S1(k, p) and S2(k, p) will all appear at the following positions:

[0080]

[0081] P peak = f rd T D L Z + L Z .

[0082] Wherein, K peak is the range direction frequency corresponding to the maximum amplitude of S1(k, p) or S2(k, p), and P peak is the Doppler frequency corresponding to the maximum amplitude of S1(k, p) or S2(k, p).

[0083] S15, the phase of the complex signal at the peak of S1(k, p) is obtained as and the phase of the complex signal at the peak of S2(k, p) is obtained as

[0084]

[0085]

[0086] In the above formula, arg(·) is the phase operation, and round(·) represents the rounding function.

[0087] Define phase difference variable for

[0088]

[0089] Therefore, we can obtain

[0090]

[0091] For ease of analysis, define for

[0092]

[0093] In practice, due to noise, the above formula is rewritten as follows:

[0094]

[0095] in, The phase of the noise.

[0096] S16. Obtain the number N of solvable fuzzy multiples. q The minimum value of the solvable fuzzy multiple q min And set the reference phase, specifically as follows:

[0097] Where gcd(·) is the greatest common divisor.

[0098] Where % represents the remainder.

[0099] Therefore, based on the number N of solvable fuzzy multiples q The minimum value of the solvable fuzzy multiple q min The reference phase is set as follows:

[0100]

[0101] S17. Obtain the fuzziness factor, specifically by processing the data of the regular sequence A1 and the defuzzified sequence B1. Value and N q By comparing the reference phases, the index i with the smallest difference is obtained, and the ambiguity factor is q. min +i.

[0102] S18. Repeat steps S12 to S17, sequentially according to the conventional sequence A. m Defuzzy sequence Bm The phase difference is solved to obtain the corresponding ambiguity multiple q', and z·N r ambiguity multiples q' are obtained, where m=1, 2,..., z.

[0103] S2, solving the blurring speed, specifically,

[0104] One channel obtains one RD image, N t ·N r channels obtain N t ·N r RD images, and N t ·N r RD images are incoherently superimposed, and the target is detected on the incoherently superimposed RD image. Assuming that the speed dimension index corresponding to the target is p peak , the blurring speed V amb is

[0105]

[0106] where V res is the speed resolution, T f is the frame period.

[0107] S3, taking the mode of the ambiguity multiple, and calculating the deblurred target speed, specifically comprising:

[0108] S31, taking the mode of the plurality of ambiguity multiples as the final ambiguity multiple: in the z·N r ambiguity multiples q' obtained in the step S1, the mode thereof is taken as the final ambiguity multiple q=mode(q'), and mode(·) is a mode operation;

[0109] S32, according to the blurring degree V amb of the target obtained in the step S2, combining the final ambiguity multiple q obtained in the step S41, calculating the deblurred target speed V, and the calculation formula is:

[0110]

[0111] In the preferred embodiment, the simulation 2 sends 16 time division MIMO radar, increases 1 deblurring sequence, the frequency modulation signal bandwidth B=100MHz, the frequency modulation period T=24us, the chirp signal polarity is positive, the delay time a=12us, the measurable speed range without taking the speed ambiguity suppression measure is-11.6m / s~11.6m / s, the speed range that can be deblurred by using the method of the application is-81.1m / s~81.1m / s, the target speed is set to 70m / s, the signal-to-noise ratio (SNR) of the simulated RD complex data is respectively taken as 10dB, 12dB, 14dB, 16B, 18dB, 20dB. Under each SNR condition, 100 Monte Carlo experiments are carried out to calculate the speed ambiguity multiple by using the method of the application and the conventional method respectively, and the speed ambiguity multiple accuracy rate is counted as shown in Table 1. Figure 3 As shown in Table 1, under the simulation parameter setting of the preferred embodiment, the application can significantly improve the accuracy rate of ambiguity multiple calculation.

[0112] In summary, compared with the prior art, the MIMO radar waveform design method for suppressing speed ambiguity proposed in the application can flexibly set the number of deblurring sequences inserted according to the frame period requirement, greatly improves the deblurring accuracy rate by taking the mode of multiple ambiguity multiples, and is suitable for target speed estimation of vehicle-mounted millimeter wave radar.

[0113] Although the content of the application has been described in detail through the above preferred embodiment, it should be recognized that the above description should not be considered as limiting the application. After reading the above content, various modifications and alternatives of the application will be obvious to those skilled in the art. Therefore, the protection scope of the application should be defined by the appended claims.

Claims

1. A method for MIMO radar waveform design to suppress velocity ambiguity, characterized in that, The method comprises the following steps: S1, insert z deblurring sequences according to frame period requirements: have N t transmit antennas, N r receive antennas MIMO radar uses time division transmission waveform, transmit antennas according to 1, 2, …, N t in turn open, while N r receive antennas simultaneously receive each transmit antenna generated echo signal, insert z deblurring sequence, z is a positive integer, and the starting time of deblurring sequence and the end time of the previous regular sequence interval certain delay time a; after mixing the echo signal with the corresponding transmission signal to get beat signal, according to the beat signal phase difference of regular sequence and deblurring sequence transmitted by the same transmit antenna to solve the ambiguity factor, and, for each receive antenna, can solve one ambiguity factor for each inserted deblurring sequence; S2, obtaining the fuzzy velocity of the target; S3, taking the mode of the velocity fuzzy multiple to calculate the target velocity after deblurring; The step S1 specifically comprises: S11, insert z deblurring sequence: the first transmission antenna 1 transmits the first linear frequency modulation signal as a regular sequence A1, interval delay time a, and then transmits the second linear frequency modulation signal as a deblurring sequence B1; the second transmission antenna transmits the linear frequency modulation signal as a regular sequence A2 immediately after the deblurring sequence B1, interval delay time a, and then transmits the linear frequency modulation signal as a deblurring sequence B2; …; the zth transmission antenna transmits the linear frequency modulation signal as a regular sequence A immediately after the deblurring sequence B Z-1 ; the (z+1)th transmission antenna transmits the linear frequency modulation signal as a regular sequence A Z ; the Nth transmission antenna transmits the linear frequency modulation signal as a regular sequence A Z . t Z+1 Nt ;​​ S12, calculating the beat signal s1(n, l) of the (l+1)th period of the conventional sequence A1; S13, calculating the beat signal s2(n, l) of the (l+1)th period of the deblurring sequence B1; S14, performing two-dimensional discrete Fourier transform (DFT) on the beat signal s1(n, l) of the (l+1)th period of the conventional sequence A1 obtained in the step S12 and the beat signal s2(n, l) of the (l+1)th period of the deblurring sequence B1 obtained in the step S13 to obtain S1(k, p) and S2(k, p), and further to obtain a range-velocity graph; S17, obtaining a group of velocity fuzzy multiples of the range-velocity graph; The step S12 specifically comprises: S15, obtain the phase of the complex signal at the peak of S1(k,p) and Phase of complex signal at peak of S2(k,p) S16, obtaining the number N of resolvable ambiguous multiples q and the minimum value q of resolvable ambiguous multiples min and setting the reference phase; The echo signal is mixed with the transmission signal to obtain the beat signal, and the beat signal s(n) of the first period of the conventional sequence A1 is: S18, repeat the steps S12 to S17 according to the phase difference of the conventional sequence A m , the deblurring sequence B m to solve the corresponding ambiguity factor q', a total of z·N r ambiguity factors q', wherein m = 1, 2, …, z.

2. The MIMO radar waveform design method for suppressing velocity ambiguity according to claim 1, wherein, The step S13 specifically comprises: according to the calculation method of the beat signal s1(n, l) of the (l+1)th period of the conventional sequence A1 in the step S12, the beat signal s2(n, l) of the (l+1)th period of the deblurring sequence B1 is obtained as: The calculation formula of the two-dimensional discrete Fourier transform (DFT) in the step S14 is: Wherein, j = sqrt(-1), that is the square root of -1, n is the sampling point of distance, chirp signal is positive frequency modulation, R is the distance of the target at the starting time of sampling, c is the speed of light, B, T are the bandwidth and frequency modulation period of the linear frequency modulation signal, N is the sampling point number in a frequency modulation period, V r is the set target speed, f0 is the radar carrier frequency, is the difference frequency generated by the coupling of distance and speed in a frequency modulation period; Due to the target motion, at the beginning of the (l+1)th cycle, the distance of the target is R+V r Tl, the beat signal s1(n, l) of the (l+1)th cycle of the conventional sequence A1 is: where l is the transmit period of the same sequence, ignoring the beat frequency variation caused by target motion, the above formula is simplified as: where, is the Doppler frequency; let T D is the period of the same sequence, and T D = N t T+z(T+a), q is the ambiguity factor, then where f rd is the ambiguous Doppler frequency, and the above formula is written as:

3. The MIMO radar waveform design method to suppress speed ambiguity as claimed in claim 2, wherein, The step S15 specifically comprises:

4. The MIMO radar waveform design method for suppressing velocity ambiguity according to claim 3, wherein, Therefore, the following formula can be obtained: where N Z , L Z are the DFT point numbers in the range and velocity directions, respectively, S1(k, p) is the two-dimensional DFT result of s1(n, l) of the regular beat signal A1, S2(k, p) is the two-dimensional DFT result of s2(n, l) of the deblocked beat signal B1, k is the range frequency, and p is the Doppler frequency.

5. The MIMO radar waveform design method to suppress speed ambiguity as claimed in claim 4, wherein, In actual cases, due to the existence of noise, the above formula is rewritten as: where arg(·) is a phase taking operation, round(·) represents a rounding function, k peak is the range-Doppler frequency corresponding to the maximum amplitude of S1(k, p) or S2(k, p), p peak is the Doppler frequency corresponding to the maximum amplitude of S1(k, p) or S2(k, p). Defining the phase difference variable is: The step S16 specifically comprises: For the convenience of analysis, define as: The steps of obtaining the beat signal of the (l+1)th period of the deblurring sequence B1 are the same as those of the conventional sequence A1. wherein is the phase of the noise.

6. The MIMO radar waveform design method to suppress speed ambiguity as claimed in claim 5, wherein, The step S2 specifically comprises: Number of blur multiples where gcd( ) is the greatest common divisor; Blur multiple minimum value Where % is the remainder. The reference phase is set as:

7. The MIMO radar waveform design method to suppress speed ambiguity as claimed in claim 6, wherein, The step S18 is specifically: calculating the beat signal of the (l+1)th period of the regular sequence A m The step of calculating the beat signal of the (l+1)th period of the deblurring sequence B is the same as the step of calculating the beat signal of the (l+1)th period of the regular sequence A1; calculating the deblurring sequence B m The step of calculating the beat signal of the (l+1)th period of the deblurring sequence B is the same as the step of calculating the beat signal of the (l+1)th period of the regular sequence A1; calculating the deblurring sequence B The step S3 specifically comprises:

8. The MIMO radar waveform design method to suppress speed ambiguity as claimed in claim 6, wherein, ​ One channel gets one RD map, N t • N r channels get N t • N r RD maps, N t • N r distance-velocity maps are incoherently stacked, targets are detected on the incoherently stacked distance-velocity map, and the ambiguous velocity V amb : where V res is the velocity resolution, T f is the frame period.

9. The MIMO radar waveform design method to suppress speed ambiguity of claim 1, wherein, ​ S31. Take the z·N obtained in step S1. r The mode of a fuzzy multiple q′ is obtained, and the mode is taken as the final fuzzy multiple q, q = mod e(q′), where mod e(·) is the mode selection operation; S32, calculating the deblurring target speed V according to the blurring speed V of the target obtained in the step S2 and the final blurring multiple q obtained in the step S31, the calculation formula being: amb wherein T D is the period of the same sequence.​

Images