CN-116990794-B - MIMO radar target detection method and device based on DDMA waveform modulation

Abstract

The invention discloses a method and a device for detecting a MIMO radar target based on DDMA waveform modulation, wherein the method comprises the steps of receiving echo signals of DDMA waveforms transmitted by a MIMO radar system, sequentially carrying out distance dimension FFT calculation and speed dimension FFT calculation to obtain a distance Doppler data matrix, dividing a space domain range to be searched into a plurality of sub-spaces, sequentially carrying out cyclic hypothesis test of the distance Doppler data matrix on each sub-space, carrying out cyclic hypothesis test of the distance Doppler data matrix, wherein the cyclic hypothesis test comprises cyclic hypothesis transmitting antenna sequences and constructing a virtual MIMO array for DBF, and judging whether target signals exist in corresponding directions of each sub-space according to a virtual MIMO array DBF result obtained by each cyclic hypothesis. The invention has the advantages of simple implementation method, low cost, good weak target detection performance, long detection distance, low report missing rate and the like.

Inventors

• WANG SHUAI
• WANG YU
• LI PEIPEI

Assignees

• 成都纳雷科技有限公司

Dates

Publication Date

20260508

Application Date

20230725

Claims (10)

1. 1. The MIMO radar target detection method based on DDMA waveform modulation is characterized by comprising the following steps: Receiving an echo signal of a DDMA waveform transmitted by a MIMO radar system, and sequentially performing distance dimension FFT calculation and speed dimension FFT calculation to obtain a distance Doppler data matrix; dividing the space domain range to be searched into a plurality of sub-spaces, sequentially carrying out cyclic hypothesis test on the distance Doppler data matrix on each sub-space, wherein the cyclic hypothesis test on the distance Doppler data matrix comprises cyclic hypothesis transmitting antenna sequences, constructing a virtual MIMO array for DBF, and judging whether target signals exist in the corresponding directions of each sub-space according to the DBF result of the virtual MIMO array obtained by each cyclic hypothesis.
2. 2. The DDMA waveform modulation based MIMO radar target detection method of claim 1, wherein the cyclically hypothesizing the transmit antenna order comprises cyclically hypothesizing that some of all the doppler cells contain target signals, extracting the doppler cells hypothesized to contain target signals, and obtaining the hypothesized transmit antenna order.
3. 3. The DDMA waveform modulation based MIMO radar target detection method of claim 1, wherein the constructing a virtual MIMO array for DBF comprises: searching corresponding receiving channel data according to the transmitting antenna data obtained by the transmitting antenna sequence assumed each time; according to the determined receiving channel arrangement sequence of the searched receiving channel data, constructing a corresponding virtual MIMO array; and performing DBF on the target signal vector of the virtual MIMO array according to the pointing angle of the current sub-airspace to obtain a synthesized value for output.
4. 4. The method for detecting the target of the MIMO radar based on the DDMA waveform modulation according to claim 3, wherein the step of judging whether the target signal exists in the direction corresponding to each sub-space domain according to the virtual MIMO array DBF result obtained by each cycle hypothesis comprises the steps of judging the synthesized value obtained by each hypothesis, judging that the target signal exists in the direction corresponding to the sub-space domain if a plurality of synthesized values are larger than a preset threshold value, and determining the position in the sub-space domain where the first transmitting antenna is located according to the position where the maximum value of the synthesized value is located, namely determining to obtain the sequence of the transmitting antennas.
5. 5. The method for detecting a target of a MIMO radar based on DDMA waveform modulation according to claim 1, wherein the number of times of detection is assumed to be N Chirp ,N Chirp in the cyclic hypothesis test as the length of the doppler cell, each hypothesis corresponds to a transmit antenna channel sequence.
6. 6. The method for detecting MIMO radar targets based on DDMA waveform modulation according to any one of claims 1 to 5, wherein the space domain to be searched is divided into a plurality of sub-space domains, the number of the divided sub-space domains is N th , the sub-space domain pointing angle is θ i = - θ [ (i-1) Δθ, iΔθ ], and the sub-space domain interval is [ - Θ, +θ ] is the airspace range to be searched, θ i is the sub airspace pointing angle of the i-th sub airspace, i=1, 2.
7. 7. The method for detecting a target of a MIMO radar based on DDMA waveform modulation according to any one of claims 1 to 5, wherein the sequentially performing distance-dimensional FFT computation and velocity-dimensional FFT computation to obtain a distance-doppler data matrix includes: Carrying out one-dimensional distance dimension FFT calculation on each receiving channel of the echo signal to obtain a one-dimensional distance matrix; and carrying out pulse accumulation and two-dimensional speed dimension FFT calculation on each distance unit in the distance matrix to obtain the distance Doppler data matrix.
8. 8. The method for detecting a target of a MIMO radar based on DDMA waveform modulation according to any one of claims 1 to 5, wherein the cyclic detection further comprises performing angle measurement according to the constructed virtual MIMO array and the detected target signal, and determining whether the detected target signal is a real target according to the correspondence between the angle measurement result and the pointing angle range of the corresponding sub-airspace.
9. 9. The method for detecting the target of the MIMO radar based on the DDMA waveform modulation according to claim 8, wherein the step of confirming whether the detected target signal is a real target according to the corresponding relation between the angle measurement result and the pointing angle range of the corresponding sub-airspace comprises the steps of judging the target signal as the real target if the angle measurement result of the target signal is within the pointing angle range of the corresponding sub-airspace, and judging the target signal as a false target if the angle measurement result of the target signal is not within the pointing angle range of the corresponding sub-airspace.
10. 10. A MIMO radar target detection apparatus based on DDMA waveform modulation, comprising a processor and a memory for storing a computer program, wherein the processor is configured to execute the computer program to perform the method of any one of claims 1-9.

Description

MIMO radar target detection method and device based on DDMA waveform modulation Technical Field The invention relates to the technical field of radar target detection, in particular to a MIMO radar target detection method and device based on DDMA waveform modulation. Background MIMO (Multiple-Input Multiple-Output) radars are waveforms that transmit diversity synchronously with Multiple transmit antennas while receiving echo signals using Multiple receive antennas. The virtual channel number of the radar can be increased through the MIMO technology, so that the detection performance of the radar is improved. For a MIMO radar system comprising N Tx transmit antennas and N Rx receive antennas, a virtual antenna array of N Tx×NRx may be formed by using a suitable antenna layout and waveform design, and by performing a receive DBF (Digital Beam Forming ) on the received signal in the desired direction, the detection gain of the system in the desired direction may be improved. In order to form the virtual antenna array, the transmitting end must be able to multiplex waveforms of N Tx transmitting antennas in a certain dimension, and the receiving end must be able to separate waveforms of N Tx transmitting antennas in the same dimension after receiving the waveforms. DDMA (Doppler multiple access) is a method in which signals from different transmitting antennas are separated in the Doppler domain by transmitting all transmitting antennas simultaneously, and each transmitting antenna's signal is shifted by a specific frequency. The adoption of DDMA (Doppler multiple access) in the MIMO radar can realize the simultaneous transmission of all transmitting antennas (N Tx), compared with the traditional TDMA (time division multiple access) mode, the transmission time of one pulse can be reduced, and the detection gain of the virtual antenna DBF can be ensured under the condition of the same transmission signal time. In DDMA, the target signal needs to be detected at the receiving end, and then different transmitting antennas need to be separated at the receiving end, that is, the sequence of the transmitting antennas needs to be determined at the receiving end, and before the sequence of the transmitting antennas is not determined, the virtual antenna DBF cannot be performed, but only the DBF of the receiving channel can be performed. Therefore, the premise of using the DDMA is that the target signal can be analyzed in the target signal detection stage, otherwise, the DBF gain of the transmitting antenna cannot be reflected. In the prior art, when a DDMA method is adopted in a MIMO radar, echo signals are generally accumulated in a pulse mode, and since transmission antennas are not separated, only a receiving channel DBF can be performed at this time, then a detection algorithm is used to detect a two-dimensional data matrix after receiving the DBF, transmission is decoupled according to detected values, and a sequence of the transmission antennas is determined for a signal processing algorithm such as a subsequent angle measurement. For the target with stronger echo signals, target signal detection can be realized through pulse accumulation gain and receiving channel DBF gain, so that different transmitting antenna sequences are determined, and then algorithm processing such as angle measurement is performed by using a virtual array. However, for targets with weaker echo signals (possibly with smaller target RCS, or with a longer target distance from the radar system, etc.), the DBF signal gain through the pulse accumulation and reception channels is still insufficient to enable detection of the target signal, i.e. the target signal cannot be detected during the target detection phase, so that different transmit antennas cannot be separated, and subsequent algorithm processing cannot be performed. In conclusion, the MIMO radar system adopts DDMA to detect weak targets, the detection distance of the system is relatively short, and the radar system has the risk of missing report. Disclosure of Invention Aiming at the technical problems existing in the prior art, the invention provides the MIMO radar target detection method and device based on DDMA waveform modulation, which have the advantages of simple implementation method, low cost, good weak target detection performance, long detection distance and low false alarm rate. In order to solve the technical problems, the technical scheme provided by the invention is as follows: a MIMO radar target detection method based on DDMA waveform modulation includes the steps: Receiving echo signals of DDMA waveforms transmitted by a MIMO radar system, and sequentially performing distance dimension FFT (fast Fourier transform) calculation and speed dimension FFT calculation to obtain a distance Doppler data matrix; dividing the space domain range to be searched into a plurality of sub-spaces, sequentially carrying out cyclic hypothesis test on the distance Doppler data matrix on