Fig. 1. Schematic diagram of pulsed laser ranging system

Fig. 2. Error analysis of threshold method

Fig. 3. Schematic diagram of peak holding circuit designed based on OPA615

Fig. 4. Simulation results of peak holding circuit

Fig. 5. High-speed ADC measurement of the broadened echo pulse

Fig. 6. Automatic gain control timing based on FPGA

Fig. 7. Comparison diagram of output waveform when the system receives the echo. (a) Echo is abnormal with gain change; (b) echo is normal without gain change

Fig. 8. Comparison of echo pulse waveforms with and without automatic gain control system when changing distance. (a) Distance between the target and the ranging system is 2.0 m; (b) distance between the target and the ranging system is 1.5 m; (c) distance between the target and the ranging system is 0.5 m

Fig. 9. Improved laser ranging system based on automatic gain control

Fig. 10. Comparative test of laser ranging system with and without automatic gain control. (a) Test of laser ranging system without automatic gain control; (b) test of laser ranging system with automatic gain control