A Velocity Ambiguity Resolving Method of Vehicle FMCW Radar Based on tdm MIMO

Abstract

The invention discloses a method for solving vehicle-mounted FMCW radar velocity ambiguity based on TDM MIMO, which includes the following steps: constructing a multiple-input-output MIMO antenna array; transmitting antennas sequentially transmitting FMCW waves until all transmitting antennas complete transmission, which is a MIMO cycle; Repeat previous step for MIMO num Two-dimensional FFT is performed on the obtained MIMO difference frequency signal, and the distance and ambiguity velocity of the target are calculated; after that, Doppler phase compensation and Doppler ambiguity compensation are performed on the target to obtain the true velocity of the target. The present invention searches and calculates the Doppler compensation factor, so that the third-dimensional FFT has no residual phase; before the third-dimensional FFT, in addition to Doppler phase compensation, Doppler ambiguity compensation is also performed, which solves the FMCW radar velocity ambiguity caused by TDM MIMO It improves the range of speed measurement and ensures the accuracy of angle measurement without losing the high angle resolution characteristics brought by MIMO, which greatly expands the practicability of this technology in the field of automotive radar.

Description

technical field [0001] The invention belongs to the field of automotive radar applications, in particular to a method for solving vehicle-mounted FMCW radar velocity ambiguity based on TDM MIMO. Background technique [0002] In the active and safe driving technology of automobiles, millimeter-wave radar has gradually become an indispensable detection sensor due to its all-weather and all-day significant advantages. Of course, it also has its own weaknesses. For example, compared with lidar, its distance resolution The rate and angular resolution are relatively low. However, with the continuous advancement of technology and the increase in the computing power of processing chips, millimeter-wave radars are gradually developing towards high-resolution. [0003] The distance resolution of FMCW radar can be achieved by increasing the bandwidth of the modulated signal, while the angle resolution needs to increase the antenna aperture. MIMO antenna array is considered to be an i...

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Problems solved by technology

[0004] Although MIMO based on TDM technology can increase the antenna aperture and improve the angular resolution, it has its own shortcomings. First, TDM itself reduces the sampling rate in the slow time, so that the maximum unambiguous speed is proportional to the number of transmitting antennas. inverse ratio

Second, due to the phase shift caused by the Doppler frequency of the moving target in different transmitting antenna switching times, it will be coupled to each receiving channel, affecting the correct synthesis of the receiving antenna aperture, so that the target outside the maximum unambiguous velocity range The angle measurement of the

[0005] Due to the shortcomings of the above-mentioned MIMO based on TDM technology, the maximum unambiguous speed measurement range is reduced, which greatly limits its practicability. There is an existing method to solve this problem. For example, the application number is 201810376216.6, and the name is "A car Radar Velocity Defuzzification Method” patent, which calculates a total of M×N third-dimensional FFT results of M transmitting antennas and N receiving antennas, and analyzes the main-to-negative lobe ratio of each third-dimensional FFT result to solve the velocity. It can be seen that the amount of calculation is huge, especially when there are too many transmitting antennas and receiving antennas, the practicability of this method will be greatly reduced

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