FPGA-Based Dual-Pulse Anti-Interference Lidar System Using Digital Chaotic Pulse Position Modulation

We investigated an FPGA-based dual-pulse anti-interference light detection and ranging (LiDAR) system with digital chaotic pulse position modulation (DCPPM). The dual-pulse signal is a periodic pulse pair, in which the first pulse is a periodic pulse, and the second pulse based on DCPPM is a pulse with a random time interval from the first pulse in each period. The real-time generation and detection of the position-modulated dual-pulse are realized by a field-programmable gate array (FPGA). The DCPPM-based dual-pulse lidar system integrates the characteristics of anti-interference, high pulse peak power, and fast measurement. In this letter, the repetition frequency of the dual-pulse signal is 100kHz. There is an initial time interval of 128ns between dual pulses, the step number of random time interval between dual pulses is 0~255, and the step accuracy is 6.4ns. Under a 1.25GSa/s sampling rate of the analog to digital converter (ADC), an accuracy within ±6cm has been obtained. Finally, under 100kHz periodic pulse interference and 100kHz DCPPM-based dual-pulse interference, the probability of correct detection has been counted every 250 measurements (up to 2000 times). The two correct detection probabilities with average values above 99% have been obtained, which are respectively 99.29% and 99.68%. The good anti-interference performance of the proposed lidar system has been verified.