Multi-hit Method for Weak Signal Detection of the Diffuse Reflection Laser Ranging in Daylight

Abstract

Because of the strong background noise, the weak echo signal in diffuse reflection laser ranging is very difficult to detect in daylight, which limits the extensive application of diffuse reflection laser ranging. In this paper, the multi-hit method is proposed to solve the weak signal detection problem of diffuse reflection laser ranging in daylight. First of all, a fast performance prediction method for multi-hit Geiger-mode avalanche photodiode (GM-APD) is introduced. Then, taking the typical parameters of the diffuse reflection laser ranging system, the detection probability of the echo signal is analysed under different firing times. Furthermore, effective detection ratio is defined to evaluate the extraction cost of the echo signal. The theoretical analysis shows that processing only a few firings in one gate window can result in large increase of detection probability for diffuse reflection laser ranging in daylight. Meanwhile the optimization of the firing time for GM-APD can increase the effective detection ratio and reduce the extraction cost of the echo signal. Finally, the correctness of the theoretical analysis is verified by the system simulation. Therefore, the multi-hit method is one of the feasible ways to detect the weak echo signal of the diffuse reflection laser ranging in daylight.