Multi-channel high-repetition-frequency large-dynamic-range distance and speed measurement laser radar method and device

Abstract

The invention discloses a multi-channel high-repetition-frequency large-dynamic-range distance measurement and speed measurement laser radar method and device. A laser light source generates a light beam, the light beam is divided into output light beams of N channels through a beam splitter, broadband linear frequency modulation is carried out on the output light beams of each channel, and then aphase modulator is driven after phase shift of different amplitudes, so that the output light beams of each channel have different time delays; the laser beam is divided into a local oscillation light beam and an emission light beam through a beam splitter; the N transmitting light beams are transmitted to a target in parallel and echo light beams of the target are received, coherent light mixingis carried out on the signals and corresponding local oscillation light beams, intermediate frequency signals containing target distance and speed information are obtained, parallel fast Fourier transform and cross-spectrum processing are carried out on sampling data of the intermediate frequency signals, parallel synchronous measurement of the target distance and speed is achieved, and finally merging output of point cloud images of N channels is achieved through a main control computer. The device can effectively overcome distance measurement ambiguity, and has the advantages of high repetition frequency, large dynamic distance measurement range, high resolution, high precision, high reliability, small size, light weight and the like.

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...

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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

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