Study On The Echo Signal Processing Technology Of Diode Laser Range Finder

In this thesis, it studied the semiconductor laser pulse ranging system receiver circuit in depth. The system used APD as a photoelectric detector, it convert laser pulse echo signals into a weak current signal, after two-step enlarges, signal amplitude increases, inputs comparator.Since receiving the laser pulse echo inevitable mixed with noise and interference, we have to design the laser echo receiver circuit in the low SNR state the working. In order to maximize to suppress noise and extract the really echo signal, we design noise automatic threshold circuits and echo signal identification circuit. The adjusting process is that CPU controls the resistance of digital potentiometer, sets different initial threshold value, thus changing the sensitivity of the receiving system can accurately identify Echo in the different Noise working environment and improve the accuracy of ranging. Use the computer simulation technology to simulate the automatic noise threshold, the experimental and theoretical calculation, it designed a optimal threshold circuit under different working environment.