TDM MIMO based speed defuzzification method for vehicle-mounted FMCW radar

Abstract

The invention discloses a TDM MIMO based speed defuzzification method for a vehicle-mounted FMCW radar. The method comprises the following steps that a multi-input-multi-output (MIMO) antenna array isconstructed; transmitting antennas emit FMCW successively, and one MIMO period is realized when all the transmitting antennas complete emission; the last step is repeated to realize MIMOnum periods;2D FFT is carried out on an obtained MIMO difference frequency signal, and the distance and fuzzy speed of a target are calculated; and then Doppler phase compensation and Doppler fuzzy compensation are carried out on the target to obtain the real speed of the target. According to the method, a Doppler compensation factor is searched and calculated so that the third dimension FFT has no residual phase; and before the third dimension FFT, both Doppler phase compensation and Doppler fuzzy compensation are carried out, so that the problem of speed fuzziness of the FMCW radar due to TDM MIMO is solved, the speed measurement range is widened, the accuracy of angle measurement is ensured, there is no loss in the high-angle resolution of MIMO, and the method is more practical in the automobile radar field.

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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