Development Of Multi-channel Signal Receiving And Processing Circuit In Lidar

Real-time detection, discrimination and processing of multi-channel echo signal in lidar system have important significance to realize the overall performance of radar system. This thesis is devoted to the research on the scheme of multi-channel signal acquisition and processing in bistatic lidar system and the development of the receiving and processing circuits of multi-channel signal specific to 24-channel signal-receiving system in bistatic lidar system.Firstly, the correlation theory of lidar and the scheme of multi-channel signal- acquisition and signal-processing in bistatic lidar system are introduced in this paper. Based on the structure and working principle of monostatic / biststic lidar system, the acquisition circuit and processing circuit of multi-channel signal are developed to meet the requirements of echo signal acquisition and processing in lidar system. Signal-acquisition circuit can realize real-time receiving of lidar echo signals. In the circumstance of strong background light, the peak value of noise amplitude is under 40 mV. Using high-speed comparator and MAX3000A series of CPLD chip, signal-processing circuit has completed real-time accurate detection and discrimination of the 24-channel signal. With TDC chip, signal-processing circuit has completed the high-accuracy (125 ps) time-interval measurement. With QUARTUS II software applied, signal-processing circuit has accomplished the output of the channel number information which will assist to locate the target of lidar system. When high laser echo pulses are of frequency (10 kHz), multichip communication among TDC, CPLD and MCU is achieved and signal real-time processing is completed. High-speed (921600bit/s) data transmission between MCU and computer is achieved with communication programs designed in this paper. In addition, on the basis of the requirements of time-scale synchronization in lidar system, the scheme of optical fiber transmission is designed and interface circuit of optical transceiver is developed.Finally,systematical test and analysis are proceeded on the circuits in lidar system. Similarly the overall test of lidar principle system is completed. The results show that circuits developed in this thesis is rational and feasible. They can meet the requirements of signal acquisition and processing in the lidar principle prototype.