[ACM Press the 2019 4th International Conference - Guangzhou, China (2019.07.26-2019.07.28)] Proceedings of the 2019 4th International Conference on Robotics, Control and Automation - ICRCA 2019 - Narrow Laser Echo Signal Processing Method for Lidar Based on Transmission Pulse Spacing Modulation

摘要： Narrow laser echo signal processing plays a decisive role for digital lidar ranging system, especially, in time-of-flight (TOF) measurement accuracy and signal-to-noise ratio (SNR). It will achieve more precise resolution for time measurement with high- speed analog-to-digital converter (ADC), but it also means more expensive. Therefore, a method using transmission pulse spacing modulation, is proposed to realize high-frequency sampling with low-speed analog-to-digital converter, and then the resolution of time-measurement depends on the relationship between the modulation spacing of driving pulse and the sampling period. Consequently, the resolution can be raised to 625 ps, which is suitable for high precise time measurement. Besides, since the power of echo signal is inversely proportional to the square of the distance according to the radar function, the echo signal is weak and may be contaminated by the environment and electronic noise for the long-range lidar. Data accumulation is used to improve the SNR for the echo signal. Both simulation and experimental results show the desirability of this method.