Multi-channel high repetition frequency and large dynamic range ranging and speed lidar method and device

Abstract

The invention discloses a multi-channel high repetition frequency large dynamic range ranging and speed measuring laser radar method and device. The beam generated by the laser light source is divided into output beams of N channels through a beam splitter, and the output beams of each channel are subjected to broadband linear frequency modulation, and then After phase shifting with different amplitudes, the phase modulator is driven, so that the output beams of each channel have different time delays; and then divided into local oscillator beams and emission beams by a beam splitter; N emission beams are transmitted to the target in parallel and receive the target The echo beam is then coherently mixed with the corresponding local oscillator beam to obtain an intermediate frequency signal containing target distance and speed information, and parallel fast Fourier transform and cross-spectrum processing are performed on the sampling data of the intermediate frequency signal to achieve target distance and speed. Parallel synchronous measurement of speed, and finally the combined output of N channel point cloud images is realized by the main control computer. The invention can effectively overcome the fuzziness of distance measurement, and has the advantages of high repetition frequency, large dynamic range of distance measurement, high resolution, high precision, high reliability, small size and light weight.

Description

technical field [0001] The invention relates to the technical field of laser radar, in particular to a multi-channel high repetition frequency large dynamic range ranging and speed measuring laser radar method and device. Background technique [0002] Frequency modulated continuous wave lidar combines frequency modulated continuous wave ranging and laser detection technology in modern radar technology. This technology linearly changes the frequency of the transmitted signal in time, and measures the instantaneous frequency of the beat signal between the echo signal and the local oscillator signal to obtain target distance information and radial velocity information. Compared with pulsed laser radar, frequency modulation continuous wave laser radar has the advantages of synchronous ranging and speed measurement, large ranging / speed measuring range, high resolution, multi-target detection and target imaging, etc. field has been widely used. [0003] However, the current chir...

AI Technical Summary

Problems solved by technology

[0003] However, the current chirped FM continuous wave lidar still has the following problems: in order to obtain a larger tuning range and thus a higher range resolution, the pulse repetition frequency (PRF) is severely limited; An unresolved problem that seriously affects the accuracy of speed measurement and ranging; LFM deskewing demodulation requires the echo signal and the local oscillator signal to overlap in the time domain, which determines that it is not suitable for detection within a large dynamic range of ranging

[0012] Wu Jun et al. proposed a dual-frequency, dual-modulation, dual-local-oscillator symmetrical triangular linear frequency modulation coherent range-finding and speed-measuring laser radar system, which expanded the distance range of the symmetrical triangular linear frequency modulation ranging and speed-measuring system, and had a high detection repetition rate (Wu Jun, Hong Guanglie, He Zhiping, Shu Rong, A large-ranging dynamic range high-repetition frequency coherent ranging and speed-measuring lidar (Ⅰ): structure and performance, Journal of Infrared and Millimeter Waves, 2014, Vol.33, No.6, 680-690); theory In general, the ranging dynamic range of the system can be increased by extending the modulation period of the signal, but on the one hand, this method requires a large number of coherent beat frequency data points to be collected for spectrum analysis, and on the other hand, it also requires the modulation time bandwidth of the symmetrical triangular chirp However, it is difficult to realize broadband chirp with high linearity for a long time, which greatly increases the complexity of the system and affects the application prospect

Images