Research On Echo Processing Methods And System Of Pulsed Laser Radar

With the development of the laser technology and the electronics technology, Laser Radar technology is springing up these years and widely applied in military, scientific research and civil project. Recently, the Laser Radar is widely applied in unmanned platform, robot navigation and traffic safety, etc., which shows an extensive prospect.The pulse laser radar echo processing method and system are studied intensively in this article. Taking the characteristics of laser radar echo signal into consideration, some new ways are proposed in echo processing method, based on which short-range pulse scanning laser radar system principle prototype is developed, followed by the detailed and thorough experimental study. Detailed research contents are shown as follows1) Firstly, the significance of the research of pulsed laser radar is introduced in this paper, followed by the investigation of the recent progress about pulse laser radar. What’s more, the specific method of laser radar echo processing afterwards. The basic theory of pulse laser radar system is introduced in the following. In this part, the basic principle of distance sensor is introduced firstly, and then the laser radar detection model and the composition of the pulse laser radar system is introdused.2) A novel unequal spacing multi-pulses technology was proposed to improve the signal-to-noise ratio (SNR) of echo for the application of lidar in long distance measurement. By modulating the pulse interval between multi-pulse in the transmitting terminal, the echo signal is truncated according to the modulated interval information, followed by the accumulation of the echo signal. The simulating calculation and the experiment shows the algorithm presented in this work not only maintains the advantage of improving SNR in traditional ways, but also avoids the shortage of false alarm caused by signal superposition.3) To overcome the problem of the large dynamic range of lidar’s echo signal, a hierarchical multi-layer echo processing technology is proposed in this work, which expands the dynamic range of echo greatly.-This method process the echo signal according to signal value in different layers simultaneously, followed by the selection of appropriate data based on the priority between different layers. It is proved in experiment the outputs of signal voltage under various conditions in accordance with design requirement.4) A short-range dynamic laser echo ranging approach is presented in this paper, which solves the problem that the echo dynamic range is far lager than the dynamic range of the receiving circuit. The proposed method generated the wave that with ultra-short duration and complicate form by FPDA and high-speed DAC. Followed by the control with STC circuit to weaken the influence of the large echo dynamic range. Theoretical calculation and experimental test results show that this scheme can be used for short-range laser radar echo processing, which not only can extend the distance of the dynamic range, but also can avoid the saturation of the signal. Thus the precision is improved. 5) A short-range pulse scanning lidar system is proposed in this work, which is consisted of five subsystems:the antenna which is a coaxial monostatic scanning antenna system, position trigger laser radar transmitter subsystem, a receiver system based on STC circuit, a control system based on FPGA. Finally, experimental study is carried on for the above subsystem, followed by the systematic experiment on range-measurement system and the complete machine. Distance measurement experiment shows that the distance error is about0.1m and multiple measurement variance is under0.04m. Indoor and outdoor scanning experiment results show that the system can identify specific obstacles.