Fully Coherent Continuous Wave Doppler Radar and Its Range and Velocity Measurement Method

Abstract

The invention discloses a fully coherent continuous wave Doppler radar and its distance measurement and speed measurement method. First, the difference frequency complex signal obtained by mixing the echo signal and the transmission signal is obtained, and according to the range frequency-Doppler frequency and the target distance ‑Modulation characteristics of velocity, using the two-dimensional joint detection method of distance dimension FFT + azimuth dimension MTD, using multiple coherent high repetition frequency modulation signals to independently obtain unambiguous radial velocity information, and then introduce the velocity into the Doppler The information is removed in the distance dimension and frequency domain information to eliminate the influence of distance-velocity coupling, so as to further obtain accurate distance information. The invention has the characteristics of coherent radar speed measurement and continuous wave radar distance measurement without distance blind zone, and meets the requirements of no distance blind zone, simultaneous distance measurement and speed measurement, real-time performance, miniaturization, and low power consumption.

Description

technical field [0001] The invention relates to the field of continuous wave measuring radar, in particular to a fully coherent continuous wave Doppler radar and a method for measuring distance and speed. Background technique [0002] The traditional full-coherent radar that can measure distance and speed at the same time adopts the pulse Doppler system. The distance between the target is determined by measuring the time difference between the target reflection signal and the transmitted pulse by transmitting a coherent pulse train, and the Doppler of the echo signal is analyzed by FFT between pulses. The spectrum obtains the speed information of the target, so it has the two-dimensional measurement capability of distance and speed. However, there is a distance blind zone in this system, and in the case of high resolution requirements, the pulse system needs to take into account the requirements of both narrow pulse and large bandwidth, which increases the difficulty of sign...

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Problems solved by technology

However, there is a distance blind zone in this system, and in the case of high resolution requirements, the pulse system needs to take into account the requirements of both narrow pulse and large bandwidth, which increases the difficulty of signal generation, and the back-end signal processing requires high sampling rate. greatly increased the complexity of the system

[0003] The traditional continuous wave radar does not have a distance blind zone. On the one hand, a coherent system can be used. By analyzing the frequency spectrum of the echo signal received by the radar, the speed measurement function can be completed but the distance measurement capability is not available; on the other hand, a non-coherent system can be used. By transmitting the linear FM signal, the distance information is extracted by using the characteristics of the received frequency difference signal and the target distance mapping relationship, which has the advantages of extremely high distance resolution, greatly reduced signal processing bandwidth and no distance blind zone. However, due to the non-phase In the system, there is no Doppler information at the same time as the distance measurement, so the speed cannot be measured, and the Doppler information brought by the speed is coupled into the signal, which will lead to a large distance measurement error

[0004] The currently commonly used triangular FM continuous wave can measure distance and speed at the same time, and complete the distance-speed decoupling through positive and negative frequency sweeps, but it needs to be paired in the frequency domain

In the complex high-resolution multi-target environment background, it is difficult to achieve accurate pairing in the frequency domain, which may easily lead to target information measurement errors

Moreover, the triangular wave modulation method will double the bandwidth of the intermediate frequency at the same distance resolution, thereby increasing the sampling rate of the intermediate frequency and the amount of signal processing calculations, making it difficult to meet the real-time requirements of the system

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