Single-photon lidar range-finding by the CFAR detector

Abstract

Ultra-long-distance range-finding is often affected by scattering noise, resulting in a low signal-to-noise ratio (SNR) due to the extremely weak retro-reflected light. Due to the low SNR, it is difficult to determine the corresponding distance from the sensor during the final stage of signal processing. It is challenging to adjust the threshold to achieve both a high detection rate and a low false alarm rate. In this study, we propose an effective detector for locating low SNR targets in ultra-long-distance measurements. The detector is based on the constant false alarm rate (CFAR) processing framework widely used in radar target detection. We applied this detector for signal processing in the photon counting system for long-range, small dynamic targets, which we reported in our earlier work. In-site experiments were conducted in Dunhuang, Gansu in September 2021. We successfully performed long-range laser ranging for 60km buildings and ultra-long-range laser ranging for 152km mountain. The results showed that the proposed CFAR detector could quickly and efficiently extract target locations that were difficult to detect using a detector based on constant thresholding.