Improving the Repeatability of Laser Ranging Results Using a Selective Echo Signal Processing Algorithm

Laser rangefinders that use the fixed-threshold method are subject to walk error, which arises because the moment of signal detection depends on its amplitude. In addition, saturation of the receiver channel at short and medium ranges further distorts the shape of the registered pulse and reduces measurement accuracy. This paper presents a ranging device based on high-speed digitization of the entire echo waveform with a sampling rate of up to 500 MHz. The hardware implementation makes it possible to activate the power-consuming units of the receiver channel immediately before the start of the ranging cycle, which improves the energy efficiency of the device. To compensate for the signal attenuation proportional to the square of the range, dynamic gain control is implemented. To determine the position of the intensity peak, an algorithm is proposed that selects the registered signal by its amplitude and, depending on the presence of saturation, chooses the appropriate calculation method. Experimental comparison of the proposed method with classical algorithms was performed on targets of various reflectivity at ranges from 750 m to 12 km under different meteorological optical ranges. The experimental results demonstrated high measurement repeatability, with standard deviations ranging from 0.15 to 0.22 m, and confirmed the applicability of the proposed algorithm under different atmospheric attenuation conditions.