Radar signal demodulation method based on CDMA, millimeter wave radar and product

Abstract

The invention provides a radar signal demodulation method based on CDMA, a millimeter wave radar and a computer program product, and the method comprises the steps: firstly separating a first data submatrix of echo signals of a first transmitting antenna to determine a potential target point, and then extracting echo signal data of the potential target point from the first data matrix of all echo signals according to the potential target point, therefore, the echo signal data of the potential target point only comprises the echo signal data related to the potential target point, and the data volume required to be processed is reduced. Therefore, when the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels are separated according to the echo signal data of the potential target point and the Kth matched filtering coefficient corresponding to the Kth transmitting antenna, the data volume required to be processed is reduced; and the calculation complexity of separating signal components of different transmitting channels is reduced. According to the method, the calculated amount of signal processing for separating different transmitting antennas is reduced.

Description

Technical Field

[0001] The present application relates to the field of radar technology, and in particular to a radar signal demodulation method based on CDMA, a millimeter wave radar and a computer program product. Background Art

[0002] Millimeter-wave radar detects and tracks targets by emitting and receiving electromagnetic waves, and can simultaneously measure the distance, speed, and angle of the target. Compared with cameras and lidars, millimeter-wave radars have good environmental and weather adaptability, and can adapt to application scenarios such as strong light, night, heavy rain, fog, and dust. They have been widely used in vehicle-mounted ADAS (Advanced Driving Assistance System) assisted driving systems and vehicle-mounted AD (Autonomous Driving) automatic driving systems. Through the mutual integration of cameras, lidars, and millimeter-wave radars, the redundancy of intelligent decision-making can be improved, and the high reliability and safety of ADAS assisted driving or AD automatic driving can be achieved.

[0003] At present, the application of millimeter-wave radar in autonomous driving is mainly limited by angular resolution, which is also the main disadvantage of millimeter-wave radar compared with cameras and lidar. In order to improve the angular resolution of millimeter-wave radar, it is necessary to increase the direction-finding aperture of millimeter-wave radar. In order to increase the aperture of millimeter-wave radar, MIMO technology is usually used in the waveform design stage.

[0004] MIMO (Multiple-Input Multiple-Output) technology, also known as Multiple-Input Multiple-Output technology, can also be called Multiple Transmit Multiple Receive Antenna (MTMRA) technology. Its basic principle is to use multiple transmitting antennas Tx and receiving antennas Rx at the transmitting end and the receiving end respectively, using fewer Tx and Rx to be equivalent to a larger receiving array, thereby improving the angle measurement resolution and accuracy.

[0005] At present, the more common MIMO technologies in the field of automotive millimeter-wave radar are TDMA-MIMO, DDMA-MIMO and CDMA. Among them, the basic principle of CDMA coding is to use different orthogonal phase codes to modulate the radar transmission signal. These orthogonal phase codes are mutually orthogonal in fast time (i.e., intra-pulse modulation) or slow time (i.e., inter-pulse modulation) to ensure effective signal separation. In the traditional radar signal demodulation process based on CDMA coding, the technology for separating the echo signals of different transmitting antennas has the problem of large amount of calculation. Summary of the invention

[0006] In order to solve the existing technical problems, the present application provides a radar signal demodulation method based on CDMA, a millimeter wave radar and a computer program product which can reduce the amount of calculation and improve the processing efficiency.

[0007] In a first aspect, a radar signal demodulation method based on CDMA is provided, which is applied to a radar, wherein the number of transmitting antennas of the radar is N, and the method comprises:

[0008] For the echo signal of the transmitted signal based on CDMA coding, performing a distance-dimensional Fourier transform between the ADC sample points of each chirp to obtain a first data matrix of the echo signal;

[0009] The first data matrix is ​​processed according to a first matched filter coefficient corresponding to a first transmitting antenna to obtain a first data submatrix of an echo signal of the first transmitting antenna; the first transmitting antenna is any one of the N transmitting antennas;

[0010] Determine potential target points according to the first data submatrix, and extract echo signal data of the potential target points under the first transmitting channel received through different receiving channels;

[0011] The echo signal data of the potential target point is extracted from the first data matrix according to the potential target point, and the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels is extracted respectively according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna; the Kth transmitting antenna is the other transmitting antenna among the N transmitting antennas except the first transmitting antenna.

[0012] In a second aspect, a vehicle-mounted millimeter-wave radar is provided, comprising a millimeter-wave radar processor and a memory, wherein the memory stores a computer program executable by the millimeter-wave radar processor;

[0013] When the computer program is executed by the millimeter wave radar processor, the CDMA-based radar signal demodulation method described in any embodiment of the present application is implemented.

[0014] In a third aspect, a computer program product is provided, including a computer program, wherein when the computer program is executed by a processor, the CDMA-based radar signal demodulation method described in any embodiment of the present application is implemented.

[0015] In a fourth aspect, a vehicle is provided, comprising the millimeter wave radar of the above-mentioned embodiments.

[0016] The radar signal demodulation method based on CDMA provided in the above embodiment first separates the first data sub-matrix of the echo signal of the first transmitting antenna to determine the potential target point, and then extracts the echo signal data of the potential target point from the first data matrix of all echo signals according to the potential target point, so that the echo signal data of the potential target point only includes the echo signal data related to the potential target point. Compared with the first data matrix of all echo signals, the amount of data required to be processed is reduced. Therefore, when the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna are used to separate the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels, the computational complexity of separating the signal components of different transmitting channels is reduced due to the reduction in the amount of data required to be processed. This method reduces the computational amount of signal processing for separating different transmitting antennas, thereby reducing the computational complexity of radar signal demodulation based on CDMA.

[0017] The vehicle-mounted millimeter-wave radar, computer program product, and vehicle provided in the above embodiments belong to the same concept as the corresponding CDMA-based radar signal demodulation method embodiment, and thus have the same technical effects as the corresponding CDMA-based radar signal demodulation method embodiment, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. 4 is a schematic diagram of a MIMO array in one embodiment.

[0019] Figure 2 FIG. 4 is a schematic diagram of a TDMA-MIMO waveform in an embodiment.

[0020] Figure 3 The figure is an optional application scenario diagram of a radar signal demodulation method based on CDMA in one embodiment.

[0021] Figure 4 Schematic diagram of the working principle of a vehicle-mounted millimeter-wave radar in one embodiment.

[0022] Figure 5 The figure is a flow chart of a radar signal demodulation method based on CDMA in one embodiment.

[0023] Figure 6 The figure is a flow chart of a radar signal demodulation method based on CDMA in another embodiment.

[0024] Figure 7 The figure is a working flow chart of the vehicle-mounted millimeter wave radar in one embodiment.

[0025] Figure 8 FIG. 4 is a schematic diagram of the structure of a millimeter wave radar in one embodiment. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0028] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0029] In the following description, the terms "first, second, third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first, second, third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0030] In order to solve the problem of millimeter wave radar signal demodulation, the inventors of this application have conducted in-depth research and analysis on the principles and defects of current signal demodulation algorithms. Among them, signal demodulation is related to signal encoding. Radar signal encoding refers to the process of converting original information into a signal form suitable for transmission by the radar system. Radar signal demodulation refers to the process of extracting useful information from the received radar echo signal.

[0031] The application of millimeter-wave radar in autonomous driving is mainly limited by angular resolution, which is also the main disadvantage of millimeter-wave radar compared with cameras and lidar. In order to improve the angular resolution of millimeter-wave radar, it is necessary to increase the direction-finding aperture of millimeter-wave radar. In order to increase the aperture of millimeter-wave radar, MIMO technology is usually used in the waveform design stage. At present, the more common MIMO technologies in the field of automotive millimeter-wave radar are TDMA-MIMO and DDMA-MIMO technologies.

[0032] First, DDMA-MIMO technology

[0033] Under the DDMA waveform, all transmitting antennas transmit simultaneously, but the signal of each transmitting antenna is offset by a specific frequency. This artificially offset frequency allows the signals of different transmitting antennas to be separated in the Doppler domain (i.e., the velocity axis after the distance dimension fft and the velocity dimension fft). Under the DDMA waveform, the velocity values ​​detected in the echoes formed by a target under the illumination of the signals of different transmitting antennas are different. By utilizing this speed difference, the signals of different transmitting antennas can be separated at the receiving end for a target. It should be noted that the frequency offset on different transmitting antennas is achieved by applying different phase rotations between chirps (i.e., on the 'slow time'), while the phase of the signal within the chirp (i.e., between ADCs, i.e., on the 'fast time') is unchanged.

[0034] Assume there are N t transmit antennas, then for transmit antenna k, the phase shift ω imposed on adjacent chirps k Determined by the following formula:

[0035]

[0036] Where N ≥ N t , m does not take repeated values.

[0037] This technology has the following advantages:

[0038] 1. Good orthogonality and low velocity sidelobe;

[0039] 2. Compared with traditional TDMA-MIMO, DDMA transmission power can be superimposed, so the signal-to-noise ratio is higher and a longer detection distance can be obtained.

[0040] This technology has the following disadvantages: the unambiguous speed range is limited, and with the development of vehicle-mounted millimeter-wave radar technology, static objects have also become targets that must be detected. Since the DDMA mode divides the Doppler domain into N parts, moving targets and stationary objects are more likely to overlap, thereby increasing the probability of missed detection.

[0041] Second, TDMA-MIMO technology

[0042] TDMA waveform means time division multiple access MIMO. In automotive radar, it usually means that different Txs work in turn in time, thus equivalent to a larger array. Figure 1 Tx1 and Tx2 in the example work in turns in time, and TDMA-MIMO can eventually achieve the equivalent of Figure 1 The 1T8R receiving array on the right side of the picture. Figure 2 It is a 2T4R TDMA-MIMO mode.

[0043] This technology has the following advantages: good orthogonality and low velocity sidelobe.

[0044] This technology has the following disadvantages:

[0045] 1. The unambiguous speed range is limited. With the development of vehicle-mounted millimeter-wave radar technology, static objects have also become targets that must be detected. Since the DDMA mode divides the Doppler domain into N parts, moving targets and static objects are more likely to overlap, thereby increasing the probability of missed detection;

[0046] 2. Because Tx works in turns, Tx is not fully utilized, and the detection distance is reduced compared with DDMA.

[0047] In view of the shortcomings of the above two coding methods, the present application obtains radar transmission signals based on CDMA coding. The basic principle of CDMA coding is to use different orthogonal phase codes to modulate radar transmission signals. These orthogonal phase codes are mutually orthogonal in fast time (i.e., intra-pulse modulation) or slow time (i.e., inter-pulse modulation) to ensure effective signal separation. Different transmitting antennas simultaneously radiate CDMA-encoded transmission signals into space. These signals will be emitted to generate echo signals after encountering obstacles or other targets, and the receiving end receives the echo signals. The receiving end decodes the received echo signals through a matching filter, thereby separating the signal components of different transmitting antennas received by each receiving antenna.

[0048] Compared with TDMA coding, CDMA, like DDMA, makes full use of the superposition of transmission power, so the signal-to-noise ratio is higher and a longer detection distance can be obtained. However, CDMA coding has the problem of large amount of calculation.

[0049] To address this problem, the present application proposes a radar signal demodulation method based on CDMA, which is applied to a radar having N transmitting antennas. The method comprises: performing a distance-dimensional Fourier transform between ADC sample points of each chirp on an echo signal of a transmitting signal encoded based on CDMA to obtain a first data matrix of the echo signal; processing the first data matrix according to a first matched filter coefficient corresponding to the first transmitting antenna to obtain a first data submatrix of the echo signal of the first transmitting antenna; the first transmitting antenna is any one of the N transmitting antennas; determining potential target points according to the first data submatrix, and extracting echo signal data of potential target points under the first transmitting channel received through different receiving channels; extracting echo signal data of potential target points from the first data matrix according to the potential target points, and respectively extracting echo signal data of potential target points under each K-th transmitting channel received through different receiving channels according to the echo signal data of the potential target points and the K-th matched filter coefficient corresponding to the K-th transmitting antenna; the K-th transmitting antenna is another transmitting antenna among N except the first transmitting antenna. In this way, it is possible to demodulate and separate the echo signal data of potential target points under N transmitting channels received through different receiving channels.

[0050] The method first separates the first data submatrix of the echo signal of the first transmitting antenna to determine the potential target point, and then extracts the echo signal data of the potential target point from the first data matrix of all echo signals according to the potential target point, so that the echo signal data of the potential target point only includes the echo signal data related to the potential target point. Compared with the first data matrix of all echo signals, the amount of data required to be processed is reduced. Therefore, when the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels is separated according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna, the computational complexity of separating the signal components of different transmitting channels is reduced due to the reduction in the amount of data required to be processed. The method reduces the computational complexity of signal processing for separating different transmitting antennas, thereby reducing the computational complexity of CDMA-based radar signal demodulation.

[0051] See also Figure 3 , which is an optional application scenario diagram of the CDMA-based radar signal demodulation method provided in an embodiment of the present application applied to a vehicle. The vehicle-mounted millimeter wave radar 200 is usually installed on both sides of the front of the vehicle 100. Common installation locations are not limited to Figure 3 The forward position shown also includes the front corner, rear corner and rear corner positions, which are used to detect and perceive the surrounding environment targets (target 1, target 2, target 3).

[0052] See also Figure 4, is a schematic diagram of the structure of the vehicle-mounted millimeter-wave radar. The vehicle-mounted millimeter-wave radar mainly consists of four functional parts:

[0053] 1) Antenna array, consisting of a transmitting array and a receiving array.

[0054] 2) MRTR (Millimeter-wave Radar Transceiver, millimeter-wave radar transceiver module or chip), millimeter-wave radar transceiver functional module, mainly composed of transmitting components, receiving components and linear frequency modulation local oscillator source components. MRTR generates and transmits the working waveform signal of the millimeter-wave radar, receives and discretely samples the reflected waveform signal of the target, and sends the sampled reflected waveform signal to the MRP (Millimeter-wave Radar Processor) millimeter-wave radar processor.

[0055] 3) MRP (Millimeter-wave Radar Processor), millimeter-wave radar processor, receives the reflected waveform signal from MRTR and performs digital processing to obtain information such as the distance, speed and angle of environmental targets, clusters, identifies and tracks targets, and outputs point cloud-level detection results or target-level detection results. From the main functional division, MRP is mainly composed of distance measurement module, speed measurement module, angle measurement module and target clustering identification and tracking module. The above modules can be implemented through embedded software, FPGA (Field Programmable Gate Array) or AISC (Application Specific Integrated Circuit) application-specific integrated circuits.

[0056] The radar signal demodulation method based on CDMA provided in the embodiment of the present application is mainly implemented in the MRP speed measurement module. The implementation form, composition mode or module division mode of MRP does not affect the use of the radar signal demodulation method based on CDMA provided in the embodiment of the present application.

[0057] 4) A read-write memory used to store the working data of the millimeter-wave radar, including working parameter data and process data stored in advance.

[0058] It should be noted that the configuration form or composition method of the functional parts of the above-mentioned vehicle-mounted millimeter-wave radar does not affect the use of the CDMA-based radar signal demodulation method provided in the embodiment of the present application; in terms of application scenarios, the use of the CDMA-based radar signal demodulation method provided in the embodiment of the present application can be applied to all applications that use electromagnetic waves for target direction finding, and is not limited to vehicle-mounted millimeter-wave radar applications.

[0059] See also Figure 5 , a radar signal demodulation method based on CDMA provided in an embodiment of the present application, comprising the following steps:

[0060] S502, performing a distance-dimensional Fourier transform between ADC sample points of each chirp on the echo signal of the CDMA-coded transmission signal to obtain a first data matrix of the echo signal.

[0061] The basic principle of CDMA coding is to modulate the transmission signal using different phase code sequences. These code sequences are mutually orthogonal in fast time (i.e., intra-pulse modulation) or slow time (i.e., inter-pulse modulation). Different transmitting antennas simultaneously radiate the CDMA-encoded transmission signals into space. These signals will be emitted and generate echo signals after encountering obstacles or other targets. The receiving end receives the echo signals. The receiving end decodes the received echo signals through a matching filter, thereby separating the signal components of different transmitting antennas received by each receiving antenna.

[0062] For the original three-dimensional matrix of the echo signal, a distance-dimensional Fourier transform is performed between the ADC sample points of each chirp to obtain the first data matrix of the echo signal. In one embodiment, a distance-dimensional discrete Fourier transform (DFT) process can be performed between the ADC sample points of each chirp. Specifically, for the original three-dimensional matrix A (L, S, M) of the echo signal, a distance-dimensional L-point DFT process is performed along the dimension corresponding to L to obtain the first data matrix B (L, S, M) of the echo signal, where L is the number of ADC sample points of a single chirp, S is the number of receiving antennas (S = 4 in the example), and M is the number of chirps transmitted by a single Tx in a single frame.

[0063] Step 504: Process the first data matrix according to the first matched filter coefficient corresponding to the first transmitting antenna to obtain a first data sub-matrix of the echo signal of the first transmitting antenna; the first transmitting antenna is any one of the N transmitting antennas.

[0064] Specifically, based on the characteristics of CDMA coding, after receiving the echo signal, the receiving end usually needs to decode the received signal according to the filter of each transmission channel to separate the signal components of different transmitting antennas.

[0065] The CDMA-based radar signal demodulation method of the present application processes the first data matrix of the echo signal according to the first matched filter coefficient corresponding to the first transmitting antenna to obtain the first data sub-matrix of the echo signal of the first transmitting antenna, that is, separates the first data sub-matrix of the echo signal of the first transmitting antenna from the first data matrix, and the first data matrix only includes the most relevant signal information of the first transmitting antenna.

[0066] It should be noted that the first transmitting antenna is any one of the N transmitting antennas of the radar and should not be understood as the first transmitting antenna. In an example, the radar has two transmitting antennas, and the first transmitting antenna can be any one of the two transmitting antennas. For example, the first transmitting antenna can be the first transmitting antenna or the second transmitting antenna. In a specific implementation, if the first filter coefficient corresponding to the first transmitting antenna is used to process the first data matrix, the first data sub-matrix of the echo signal of the first transmitting antenna is obtained. If the first filter coefficient corresponding to the second transmitting antenna is used to process the first data matrix, the first data sub-matrix of the echo signal of the second transmitting antenna is obtained. In other examples of radar products with more transmitting antennas, the first transmitting antenna can be the third transmitting antenna or the fourth transmitting antenna of the radar. That is, the first matched filter coefficient corresponding to any one of the N transmitting antennas can be used to process the first data matrix to obtain the first data sub-matrix of the echo signal of the transmitting antenna.

[0067] Step 506: determine potential target points according to the first data sub-matrix, and extract echo signal data of the potential target points under the first transmission channel received through different receiving channels.

[0068] Specifically, the first data submatrix includes the distance dimension information of the echo signal of the first transmitting antenna. The speed dimension information of the echo signal of the first transmitting antenna can be obtained by performing a speed dimension Fourier transform on the first data submatrix along the chirp. Then, according to the speed distance matrix of the echo signal of the first transmitting antenna, the speed distance matrix can be beamformed along the receiving channel dimension to obtain a two-dimensional matrix, and the amplitude matrix can be calculated for the two-dimensional data matrix. The amplitude matrix is ​​detected to determine the potential target point, and the distance information and speed information of the potential target point.

[0069] After determining the potential target point, data corresponding to the potential target point is extracted from the velocity distance matrix according to the distance index and velocity index of the potential target point, and echo signal data of the potential target point under the first transmitting channel received through different receiving channels is extracted.

[0070] Step 508, extracting the echo signal data of the potential target point from the first data matrix according to the potential target point, and extracting the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna; the Kth transmitting antenna is the other transmitting antennas among the N transmitting antennas except the first transmitting antenna.

[0071] In conventional techniques, the data matrix of the echo signal is usually multiplied by the matched filter coefficients of different transmitting antennas to separate the signal components of different transmitting antennas. This process requires high computational complexity.

[0072] To solve this problem, the CDMA-based radar signal demodulation method of the present application processes the first data matrix of the echo signal according to the first matched filter coefficient corresponding to the first transmitting antenna, and separates the first data sub-matrix of the echo signal of the first transmitting antenna. Then, based on the first data sub-matrix of the echo signal of the first transmitting antenna, the potential target point is determined.

[0073] After the potential target point is determined, for each potential target point, the echo signal data of the potential target point is extracted from the first data matrix of the echo signal according to the potential target point. That is, the echo signal data of the potential target point only includes the data of the echo signal related to the potential target point, and the amount of data to be processed is reduced compared to the first data matrix of all echo signals. Therefore, when the echo signal data of the potential target point under each Kth transmitting antenna is separated according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna, the computational complexity of separating the signal components of different transmitting antennas is reduced due to the reduction in the amount of data to be processed.

[0074] The Kth transmitting antenna is the other transmitting antennas except the first transmitting antenna among the N transmitting antennas. In this embodiment, for each potential target point, the echo signal data of the potential target point is multiplied by the Kth matched filter coefficients of the other Kth transmitting antennas to separate the echo signal data of the potential target point under each Kth transmitting antenna.

[0075] In one example, the radar has two antennas, and the echo signal data of the potential target point under the first transmitting antenna has been separated in step 506. In this step, the echo signal data of the potential target point is multiplied by the second matched filter coefficient corresponding to the second transmitting antenna to obtain the echo signal data of the potential target point under the second transmitting channel received through different receiving channels.

[0076] In one example, the radar has three antennas, and the echo signal data of the potential target point under the first transmitting antenna has been separated in step 506. In this step, the echo signal data of the potential target point is multiplied by the second matched filter coefficient corresponding to the second transmitting antenna to obtain the echo signal data of the potential target point under each second transmitting channel received through different receiving channels. And, the echo signal data of the potential target point is multiplied by the third matched filter coefficient corresponding to the third transmitting antenna to obtain the echo signal data of the potential target point under the third transmitting channel received through different receiving channels.

[0077] As for the question of whether separating the echo signal data of other transmission channels will increase the amount of calculation, the inventor of the present application has conducted experiments and research and analysis and found that when separating the echo signal data of other transmission channels, the additional amount of calculation added by this method is N*M*S complex multipliers, where N represents the transmitting antenna, M represents the number of chirps transmitted by a single Tx in a single frame, and S represents the number of receiving antennas. The amount of calculation added by this step is also acceptable.

[0078] In this embodiment, the radar signal demodulation method based on CDMA first separates the first data submatrix of the echo signal of the first transmitting antenna to determine the potential target point, and then extracts the echo signal data of the potential target point from the first data matrix of all echo signals according to the potential target point, so that the echo signal data of the potential target point only includes the echo signal data related to the potential target point. Compared with the first data matrix of all echo signals, the amount of data required to be processed is reduced. Therefore, when the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels is separated according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna, the computational complexity of separating the signal components of different transmitting channels is reduced due to the reduction in the amount of data required to be processed. This method reduces the computational amount of signal processing for separating different transmitting antennas, thereby reducing the computational complexity of radar signal demodulation based on CDMA.

[0079] In one embodiment, a CDMA-based radar signal demodulation method determines the angle dimension information of the potential target point according to the echo signal data of the potential target point under N transmission channels received through different receiving channels.

[0080] Specifically, according to the echo signal data of the potential target point under N transmitting antennas, the algorithm in array signal processing or the phase difference method can be used to calculate the angle dimension information of the target point.

[0081] In one embodiment, the original three-dimensional matrix A (L, S, M) of the echo signal of the CDMA-coded transmission signal is subjected to distance dimension L-point DFT processing along the dimension corresponding to L to obtain the first data matrix B (L, S, M) of the echo signal, where L is the number of ADC sample points of a single chirp, S is the number of receiving antennas (S = 4 in the example), and M is the number of chirps transmitted by a single Tx in a single frame. After receiving, the first matched filter coefficient cof corresponding to each point in the first data matrix B (L, S, M) and the first transmitting antenna is calculated. 1m The first data sub-matrix C(L, S, M) of the echo signal of the first transmitting antenna is obtained by multiplication.

[0082] Wherein, determining the potential target point according to the first data sub-matrix includes:

[0083] Performing a velocity-dimensional Fourier transform on the first data submatrix C(L, S, M) of the echo signal of the first transmitting antenna along the chirp to obtain a distance-velocity matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna, where L represents the distance, S represents the number of receiving antennas, and M represents the speed;

[0084] Perform beamforming processing on the distance velocity matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna along the dimension corresponding to the receiving channel to obtain a first two-dimensional data matrix E(L, M) in the specified direction;

[0085] The amplitude of the first two-dimensional data matrix is ​​calculated to obtain an amplitude matrix, and the amplitude matrix is ​​tested to determine potential target points.

[0086] Specifically, the first data submatrix C(L, S, M) of the echo signal of the first transmitting antenna is subjected to the speed dimension M-point DFT processing along the dimension corresponding to M to obtain the distance speed matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna. The distance speed matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna is subjected to the DBF processing along the dimension corresponding to the receiving antenna S to obtain the first two-dimensional data matrix E(L, M) in the specified direction. The amplitude of the first two-dimensional data matrix E(L, M) is calculated to obtain an amplitude matrix, and the amplitude matrix is ​​detected to determine the potential target point.

[0087] Specifically, the first two-dimensional data matrix E(L,M) includes a distance dimension L and a speed dimension M. The amplitude of the first two-dimensional data matrix is ​​calculated to obtain an amplitude matrix; the distance index of each point in the amplitude matrix is ​​calculated to obtain the distance of the point, and the speed of the point is obtained according to the speed index of each point; the point in the amplitude matrix that meets the distance and speed requirements is determined as a potential target point.

[0088] The point that meets the amplitude requirement is the potential target point. For example, suppose there is a potential target whose distance R = l*r res ,1≤l≤L, its speed V=p*v res ,1≤p≤M, then at the first two-dimensional matrix E(l,p), its amplitude is large and meets the amplitude requirement to become a potential target point. Among them, l is the distance index and p is the speed index.

[0089] In this embodiment, the first two-dimensional data matrix is ​​obtained by performing Fourier transform of the velocity dimension on the first data submatrix and performing beamforming processing along the dimension corresponding to the receiving channel, and then the amplitude is calculated according to the first two-dimensional data matrix, and the potential target point is detected according to the amplitude information. This calculation method is simple and can quickly detect the potential target point.

[0090] In order to solve the problem of large amount of calculation for signal demodulation, the present application further proposes an optimization method when separating the echo signal of the first transmitting antenna, which can reduce the amount of calculation for signal demodulation.

[0091] Specifically, the first data matrix is ​​processed according to the first matched filter coefficient corresponding to the first transmitting antenna to obtain the first data submatrix of the echo signal of the first transmitting antenna. The specific method is usually to multiply the first matched filter coefficient corresponding to the first transmitting antenna by the first data matrix to obtain the first data submatrix of the echo signal of the first transmitting antenna. After that, in the calculation process of determining the potential target point according to the first data submatrix, the first data submatrix is ​​subjected to a velocity-dimensional Fourier transform along the chirp. Among them, when the first data submatrix is ​​subjected to a velocity-dimensional Fourier transform along the chirp, a velocity-dimensional windowing process is usually performed first. In discrete Fourier transform (DFT), windowing is an important step, which is mainly used to reduce spectrum leakage and improve the accuracy of frequency domain analysis. Windowing process specifically multiplies the data matrix by the windowing coefficient. Generally speaking, the windowing coefficient is fixed.

[0092] To reduce the amount of calculation, in this embodiment, the first data matrix is ​​processed according to the first matched filter coefficient corresponding to the first transmitting antenna to obtain the first data sub-matrix of the echo signal of the first transmitting antenna, including: obtaining the processing coefficient obtained in advance, the processing coefficient is the product of the first matched filter coefficient corresponding to the first transmitting antenna and the windowing coefficient of the velocity-dimensional Fourier transform; the first data matrix is ​​processed according to the processing coefficient to obtain the first data sub-matrix of the echo signal of the first transmitting antenna.

[0093] Specifically, the first matched filter coefficient corresponding to the first transmitting antenna is multiplied in advance with the windowing coefficient of the velocity-dimensional Fourier transform to obtain the processing coefficient. The processing coefficient can be stored in the memory of the radar. For the data separated by the first transmitting antenna, the increased computational overhead of the advance processing can be ignored, that is, the processing does not increase the computational burden. However, through this processing, the echo signal of the first transmitting antenna can be separated while the windowing coefficient of the velocity-dimensional Fourier transform is multiplied with the first data matrix in advance. In this way, the calculation of the windowing processing when the velocity-dimensional Fourier transform is performed on the first data submatrix along the chirp can be omitted, thereby reducing the calculation amount of signal demodulation.

[0094] In one embodiment, the first data submatrix of the echo signal of the first transmitting antenna is C(L, S, M), where L represents the distance, S represents the number of receiving antennas, and M is the number of chirps transmitted by a single Tx in a single frame.

[0095] Extracting echo signal data of the potential target point from the first data matrix according to the potential target point, and respectively extracting echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna, including:

[0096] According to the distance index l of the potential target point, M chirps corresponding to each receiving channel of the distance index l are extracted from the first data matrix to obtain a second two-dimensional data matrix F1(S,M) of the potential target point;

[0097] The second two-dimensional data matrix F1(S,M) of the potential target point is multiplied by the K-th matched filter coefficient corresponding to each K-th transmitting antenna to obtain the third two-dimensional matrix FK(S,M) of the potential target point under each K-th transmitting channel;

[0098] According to the velocity index p of the potential target point, the p-th point Fourier transform is performed on the third two-dimensional matrix FK(S,M) under each K-th transmission channel to extract the echo signal data of the potential target point under each K-th transmission channel received through different receiving channels.

[0099] Specifically, it is assumed that the position of the potential target point in the first two-dimensional matrix E(l,p) is (l,p). Where l is the distance index and p is the speed index. According to the distance index l, M chirps corresponding to each receiving channel S of the distance index l are extracted from the first data matrix B(l,S,m), and the second two-dimensional data matrix F1(S,M) of the potential target point is obtained. The second two-dimensional data matrix is ​​multiplied one by one with the number of K-th matched filter coefficients corresponding to each K-th transmitting antenna to obtain the third two-dimensional matrix FK(S,M) of the potential target point under each K-th transmitting channel. Then, the third two-dimensional matrix FK(S,M) under each K-th transmitting antenna is subjected to the p-th point Fourier transform to obtain the data corresponding to the S channels of the potential target point under the K-th channel at the l-th distance index and the p-th speed index, that is, the echo signal data of the potential target point under each K-th transmitting channel received through different receiving channels. In this way, the echo signal data GK(S) of the potential target point under each K-th transmitting channel received through different receiving channels except the first transmitting channel can be separated.

[0100] In this embodiment, the second two-dimensional data matrix F1(S,M) of the potential target point is obtained by extracting M chirps corresponding to each receiving channel of the distance index l from the first data matrix according to the information of the target point, and then the second two-dimensional data matrix F1(S,M) of the potential target point is multiplied by the K-th matched filter coefficients corresponding to each K-th transmitting antenna respectively, so that the data of the potential target point under each K-th transmitting antenna can be separated. Because the second two-dimensional data matrix F1(S,M) of the target point has been extracted from the first data matrix according to the information of the target point before the matched filtering process, the amount of data to be processed has been greatly reduced, and therefore, the amount of calculation of the subsequent matched filtering process can be reduced.

[0101] In one embodiment, a method for extracting echo signal data of a potential target point under a first transmitting channel received through different receiving channels includes: selecting M data of the lth distance and the pth speed in a first data submatrix according to a distance index l and a speed index p of the potential target point, and obtaining the echo signal data of the potential target point under the first transmitting channel received through different receiving channels.

[0102] Specifically, according to the distance index l and speed index p of the potential target point, M data of the lth distance dimension and the pth speed dimension are selected from the first data submatrix D(L,S,M), and the echo signal data G1(S) of the potential target point under the first transmission channel received through different receiving channels are obtained. This method can quickly extract the echo signal data of the potential target point under the first transmission channel received through different receiving channels from the first data submatrix according to the distance information and speed information of the potential target point.

[0103] The CDMA-based radar signal demodulation method of the present application, in addition to reducing the amount of calculation of the separate transmission channel in the above process, further proposes a CDMA coded waveform design scheme. The CDMA coded waveform design is also a challenge. It is necessary to design a waveform with a suitable bandwidth, pulse repetition frequency and modulation mode to ensure the performance and stability of the system.

[0104] Specifically, under the CDMA waveform, all transmitting antennas transmit simultaneously, but the signal of each transmitting antenna is randomly offset by a phase in each chirp of each transmitting antenna. Since different transmitting antennas have different phase deviations between chirps, the signals of different transmitting antennas can be separated by using matched filtering between chirps.

[0105] In an example, the transmitted waveform of each chirp is as follows:

[0106]

[0107] Wherein, N is the number of Tx antennas, in this example N = 2; M is the number of transmitted chirps, assuming M = 256; s mn_out corresponds to the signal transmitted by the nth antenna at the mth chirp; f0 corresponds to the carrier frequency of the radar transmission waveform; B0 corresponds to the frequency modulation bandwidth of a single chirp in the FMCW radar; T c The modulation time corresponding to a single chirp; θ MN The configuration value of the phase shifter corresponding to the nth antenna when the mth chirp is working.

[0108] In the embodiment of the present application, the value of θ of the same transmitting antenna Tx in M ​​chirp groups is:

[0109]

[0110] Among them, round is a rounding function; rand(1,M) means generating M random numbers uniformly distributed between 0 and 1; n is the quantization bit width of the phase shifter. For example, assuming that the phase shifter divides 360° into 128 equal parts, then n=7.

[0111] In this way, CDMA coding is implemented by adding a random phase between the chirps of different transmitting antennas Tx, wherein the random phase is a phase uniformly distributed between 0 and 360 degrees, and its anti-interference performance is improved.

[0112] Assuming that there is an external target with a distance of R and a speed of V, the intermediate frequency echo signal s received by the same Rx channel is m_in for:

[0113]

[0114] Among them, j is f R is a frequency proportional to the target distance R, f V is a frequency proportional to the target velocity V, θ 1m represents the phase shifter phase of Tx1 corresponding to the mth chirp, θ 2m represents the phase shifter phase of Tx2 corresponding to the mth chirp, and noise(t) represents the noise in the echo.

[0115] From the above formula, the matched filter coefficient corresponding to the nth Tx channel is:

[0116] cof nm =exp(jθ nm ),1≤n≤N,1≤m≤M

[0117] In order to have a more comprehensive understanding of the CDMA-based radar signal demodulation method provided in the embodiment of the present application, please refer to 6 and Figure 7 ,by Figure 4 Taking the structure of the vehicle-mounted millimeter-wave radar shown in the figure as an example, the main working process of the vehicle-mounted millimeter-wave radar and the process of the radar signal demodulation method based on CDMA are explained.

[0118] In this example, the number of radar transmitting antennas N is 2, and the number of receiving antennas S is 4. Figure 6 As shown, the radar signal demodulation method based on CDMA includes the following steps:

[0119] S11, obtain the three-dimensional matrix A(L,S,M) of the original echo signal of the CDMA-coded transmission signal, where L is the number of ADC sample points of a single chirp, S is the number of receiving antennas (S=4 in the example), and M is the number of chirps transmitted by a single Tx in a single frame.

[0120] S12, performing distance dimension L-point DFT processing on the three-dimensional matrix A(L, S, M) of the original echo signal along the dimension corresponding to L to obtain the first data matrix B(L, S, M) of the echo signal.

[0121] S13, processing the first data matrix according to the first matched filter coefficient corresponding to the first transmitting antenna to obtain a first data sub-matrix C (L, S, M) of the echo signal of the first transmitting antenna.

[0122] Specifically, for the first data matrix B(L,S,M), each point in B(L,S,m) is matched with the matched filter coefficient cof of the first transmit channel. 1m Multiply them to obtain the first data sub-matrix C(L, S, M) corresponding to Tx1.

[0123] S14, performing a velocity-dimensional Fourier transform along the chirp on the first data submatrix C of the echo signal of the first transmitting antenna to obtain a distance-velocity matrix D (L, S, M) of each receiving channel corresponding to the first transmitting antenna.

[0124] S15, the distance velocity matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna is beamformed along the dimension corresponding to the receiving antenna S to obtain the first two-dimensional data matrix E(L, M) in the specified direction.

[0125] S16, calculating the amplitude of the first two-dimensional data matrix E(L,M) to obtain an amplitude matrix.

[0126] S17, calculating the distance index of each point in the amplitude matrix to obtain the distance of the point, and obtaining the speed of the point according to the speed index of each point.

[0127] S18, determining the points in the amplitude matrix whose distance and speed meet the requirements as potential target points.

[0128] Specifically, suppose there is a potential target whose distance R = l*r res ,1≤l≤L, its speed V=p*v res ,1≤p≤M, then its amplitude is large at the two-dimensional matrix E(l,p) and meets the amplitude requirement to become a potential target point.

[0129] S19, according to the distance index l and speed index p of the potential target point, M data of the lth distance and the pth speed are selected in the first data submatrix to obtain the echo signal data G1(S) of the potential target point under the first transmitting channel received through different receiving channels.

[0130] Specifically, assuming that the potential target point is E(l,p), M data of the lth distance dimension and the pth speed dimension are selected from the first data submatrix D(L,S,M) to obtain G1(S).

[0131] S20, according to the distance index l of the potential target point, extract M chirps corresponding to each receiving channel of the distance index l from the first data matrix to obtain a second two-dimensional data matrix F1 (S, M) of the potential target point.

[0132] S21, multiply the second two-dimensional data matrix F1 (S, M) of the potential target points by the second matched filter coefficient corresponding to the second transmitting antenna to obtain the third two-dimensional matrix F2 (S, M) of the potential target points under the second transmitting channel.

[0133] S22, according to the velocity index p of the potential target point, perform Fourier transform of the p-th point on the third two-dimensional matrix F2(S,M) under the second transmission channel, and extract the echo signal data G2(S) of the potential target point under the second transmission channel received through different receiving channels.

[0134] S23, determining the angle dimension information of the potential target point according to the echo signal data G1(S)G2(S) of the potential target point under the two transmission channels received through different receiving channels.

[0135] The present application method, based on CDMA coding for demodulation, has the following advantages:

[0136] 1. Compared with TDMA, it makes full use of the superposition of transmission power like DDMA, so the signal-to-noise ratio is higher and a longer detection distance can be obtained.

[0137] 2. Compared with TDMA and DDMA, this scheme does not reduce the unambiguous speed range. When the number of Tx is large, its advantage is more obvious.

[0138] 3. Since random phase encoding is performed between chirps, its anti-interference performance is improved.

[0139] In addition, traditional CDMA coding also has the defect of relatively high sidelobes in the velocity dimension. The inventors of this application have verified through experiments that for the radar signal demodulation method based on CDMA in this application, to a certain extent, the sidelobes in the velocity dimension generated by CDMA can be reduced to an acceptable level.

[0140] The specific analysis is as follows:

[0141] Assume that the signal power of the ADC first-level target is P and the noise power is Q. After performing the range dimension FFT, the signal power corresponding to Tx1 is P + 20 * log10(L), and the noise power at this time is Q + 10 * log10(L). After performing the range dimension processing of Tx1 and the channel dimension DBF processing, the signal power corresponding to Tx1 is P + 20 * log10(L * M * S), and the noise power at this time is Q + 10 * log10(L * M * S). The sidelobe power in the velocity dimension generated by Tx2 is P + 20 * log10(L) + 10 * log10(M * S).

[0142] When P + 20 * log10(L) + 10 * log10(M * S) < Q + 10 * log10(L * M * S) (for long-distance targets, this condition is usually satisfied), the sidelobes in the velocity dimension can be ignored;

[0143] When P + 20 * log10(L) + 10 * log10(M * S) > Q + 10 * log10(L * M * S), the "signal-to-noise ratio" during detection is P + 20 * log10(L * M * S) - P - 20 * log10(L) - 10 * log10(M * S) = 10 * log10(M * S). For M = 256 and S = 4, the "signal-to-noise ratio" is 30 dB, and usually the sidelobes generated by strong targets are also at this level. Therefore, the sidelobes in the velocity dimension can be accepted at this time. Among them, M * S = 1024 is a condition that is relatively easy to meet in vehicle-mounted radars.

[0144] As for the problem of large amount of computation in CDMA demodulation, in addition to the optimization of matched filtering, when separating the signal of the first channel, the matched filter coefficient corresponding to Tx1 is multiplied with the speed dimension window coefficient in advance. Specifically, since speed dimension window processing is usually performed first when performing speed dimension DFT, the speed dimension matched filter coefficient corresponding to Tx1 can be multiplied with the speed dimension window coefficient in advance, and the multiplied result can be stored in the radar memory. Therefore, for the extraction of Tx1 channel, the increased computational overhead at this time can be ignored; for the remaining Tx channel separation, for each channel to be separated of each target, the additional amount of computation is 2*M*S complex multipliers, and the increased computational amount of this step is also acceptable.

[0145] Therefore, the radar signal demodulation method based on CDMA of the present application has the following technical effects:

[0146] 1) CDMA coding is achieved by adding a random phase between chirps of different Txs, where the random phase is a phase uniformly distributed between 0 and 360°;

[0147] 2) When the number of channels S in DBF is multiplied by the number of chirps M and is not less than 1024, the velocity sidelobes generated under normal circumstances can be ignored (the amplitude of the long-distance signal is small, and the velocity sidelobes generated by CMDA are lower than the noise level), and the velocity sidelobes generated by strong targets at close range are also acceptable (the velocity sidelobes generated by CDMA are lower than the strong target sidelobes synthesized by DBF, so they are also acceptable);

[0148] 3) Based on the CDMA channel demodulation process, the additional amount of calculation is within an acceptable range;

[0149] 4) Since this scheme does not reduce the velocity ambiguity, the detection performance of moving targets in strong static clutter is greatly improved.

[0150] Among them, the typical workflow of the vehicle-mounted millimeter wave radar using the CDMA-based radar signal demodulation method proposed in the embodiment of the present application is as follows: Figure 7 As shown, the following steps are included:

[0151] S211, the vehicle-mounted millimeter-wave radar is powered on and initialized, and the working parameters are read and sent down.

[0152] S212, the vehicle-mounted millimeter-wave radar receives an instruction to start working.

[0153] S213, the millimeter wave radar chip generates a linear frequency modulated continuous wave according to the waveform parameters, and transmits the signal to the transmitting component and the receiving component.

[0154] S214, the millimeter wave radar chip transmits a linear frequency modulated continuous wave through a transmitting antenna array.

[0155] S215, the millimeter wave radar chip receives the echo reflected by the target through the receiving antenna array.

[0156] S216, the millimeter wave radar chip is connected to the received wave for ADC sampling.

[0157] S217, the millimeter wave radar chip performs ranging processing on the ADC data.

[0158] S218, the millimeter wave radar chip performs speed measurement processing on the ranging data.

[0159] S219, the millimeter wave radar chip performs cluster tracking processing on the angle measurement results.

[0160] S220, the millimeter wave radar chip outputs point cloud information or trajectory information.

[0161] S221, the millimeter wave radar chip cyclically implements target detection until the stop working condition is met.

[0162] Among them, the CDMA-based radar signal demodulation method proposed in the embodiment of the present application can be executed by the millimeter wave radar chip, and can be specifically completed in steps S217 to S219.

[0163] On the other hand, please refer to Figure 8 , a millimeter wave radar is also provided, comprising a millimeter wave radar processor 201 and a memory 202. The memory 202 stores a computer program that can be executed by the millimeter wave radar processor 201; when the computer program is executed by the millimeter wave radar processor 201, the CDMA-based radar signal demodulation method described in any embodiment of the present application is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0164] On the other hand, an embodiment of the present application further provides a computer program product, including a computer program. When the computer program is executed by a processor, the CDMA-based radar signal demodulation method described in any embodiment of the present application is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0165] On the other hand, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the various processes of the above-mentioned CDMA-based radar signal demodulation method embodiment are implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0166] The computer-readable storage medium is, for example, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0167] On the other hand, the embodiment of the present application also provides a vehicle, which includes the millimeter wave radar of the above embodiment. The vehicle is equipped with the millimeter wave radar, and each process of the above CDMA-based radar signal demodulation method embodiment is implemented through the memory on the memory of the millimeter wave radar, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0168] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0169] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0170] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A radar signal demodulation method based on CDMA, applied to a radar, wherein the number of transmitting antennas of the radar is N, characterized in that: The method comprises: For the echo signal of the transmitted signal based on CDMA coding, performing a distance-dimensional Fourier transform between the ADC sample points of each chirp to obtain a first data matrix of the echo signal; The first data matrix is ​​processed according to a first matched filter coefficient corresponding to a first transmitting antenna to obtain a first data submatrix of an echo signal of the first transmitting antenna; the first transmitting antenna is any one of the N transmitting antennas; Determine potential target points according to the first data submatrix, and extract echo signal data of the potential target points under the first transmitting channel received through different receiving channels; The echo signal data of the potential target point is extracted from the first data matrix according to the potential target point, and the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels is extracted respectively according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna; the Kth transmitting antenna is the other transmitting antenna among the N transmitting antennas except the first transmitting antenna.

2. The CDMA-based radar signal demodulation method according to claim 1, characterized in that: The step of determining potential target points according to the first data sub-matrix includes: Performing a velocity-dimensional Fourier transform on the first data submatrix of the echo signal of the first transmitting antenna along the chirp to obtain a distance-velocity matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna, where L represents the distance, S represents the number of receiving antennas, and M represents the speed; Performing beamforming processing on the range-velocity matrix D(L, S, M) of each receiving channel corresponding to the first transmitting antenna along the dimension corresponding to the receiving antenna to obtain a first two-dimensional data matrix E(L, M) in a specified direction; The amplitude of the first two-dimensional data matrix is ​​calculated to obtain an amplitude matrix, and the amplitude matrix is ​​detected to determine the potential target point.

3. The radar signal demodulation method based on CDMA according to claim 2, characterized in that: The step of processing the first data matrix according to the first matched filter coefficient corresponding to the first transmitting antenna to obtain a first data submatrix of the echo signal of the first transmitting antenna includes: Acquire a processing coefficient obtained by pre-processing, where the processing coefficient is a product of a first matched filter coefficient corresponding to the first transmitting antenna and a windowing coefficient of the velocity-dimensional Fourier transform; The first data matrix is ​​processed according to the processing coefficient to obtain a first data sub-matrix of the echo signal of the first transmitting antenna.

4. The CDMA-based radar signal demodulation method according to claim 1, characterized in that: The first data submatrix of the echo signal of the first transmitting antenna is C(L, S, M), where L represents the distance, S represents the number of receiving antennas, and M represents the number of chirps transmitted by a single Tx in a single frame; The step of extracting the echo signal data of the potential target point from the first data matrix according to the potential target point, and respectively extracting the echo signal data of the potential target point under each Kth transmitting channel received through different receiving channels according to the echo signal data of the potential target point and the Kth matched filter coefficient corresponding to the Kth transmitting antenna, comprises: According to the distance index l of the potential target point, M chirps corresponding to each receiving channel of the distance index l are extracted from the first data matrix to obtain a second two-dimensional data matrix F1(S,M) of the potential target point; The second two-dimensional data matrix F1(S,M) of the potential target point is multiplied by the K-th matched filter coefficient corresponding to each K-th transmitting antenna to obtain a third two-dimensional matrix FK(S,M) of the potential target point under each K-th transmitting channel; According to the velocity index p of the potential target point, the p-th point Fourier transform is performed on the third two-dimensional matrix FK(S,M) under each K-th transmission channel to extract the echo signal data of the potential target point under each K-th transmission channel received through different receiving channels.

5. The CDMA-based radar signal demodulation method according to claim 2, characterized in that: The method of extracting the echo signal data of the potential target point under the first transmitting channel received through different receiving channels includes: According to the distance index l and speed index p of the potential target point, M data of the lth distance and the pth speed are selected in the first data submatrix to obtain the echo signal data of the potential target point under the first transmitting channel received through different receiving channels.

6. The radar signal demodulation method based on CDMA according to claim 1, characterized in that: The phase value of the transmitted signal of each transmitting antenna in each chirp based on CDMA coding is different; For the same transmitting sky, the phase value θ in M ​​chirp groups is: Among them, round is the rounding function; rand(1,M) means generating M random numbers uniformly distributed between 0 and 1; n is the quantization bit width of the phase shifter.

7. The CDMA-based radar signal demodulation method according to claim 2, characterized in that: The first two-dimensional data matrix includes a distance dimension and a velocity dimension; The step of calculating the amplitude of the first two-dimensional data matrix to obtain an amplitude matrix, and detecting the amplitude matrix to determine the potential target point includes: Calculating the amplitude of the first two-dimensional data matrix to obtain an amplitude matrix; Calculating the distance index of each point in the amplitude matrix to obtain the distance of the point, and obtaining the speed of the point according to the speed index of each point; The points in the amplitude matrix whose distance and speed meet the requirements are determined as the potential target points.

8. The radar signal demodulation method based on CDMA according to any one of claims 1 to 7, characterized in that: The method further comprises: The angle dimension information of the potential target point is determined according to the echo signal data of the potential target point under the N transmitting channels received through different receiving channels.

9. A millimeter wave radar, characterized in that: The invention comprises a millimeter wave radar processor and a memory, wherein the memory stores a computer program executable by the millimeter wave radar processor; When the computer program is executed by the millimeter wave radar processor, the CDMA-based radar signal demodulation method according to any one of claims 1 to 8 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the CDMA-based radar signal demodulation method according to any one of claims 1 to 8 is implemented.

11. A means of transport, characterized in that: Comprising the millimeter wave radar as claimed in claim 9.

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