AUTOMATIC GAIN CONTROL ELECTRONICS FOR FAST PULSED TIME-OF-FLIGHT LASER RANGEFINDING

摘要

The walk error of the constant fraction timing discriminator (CFD) generally used in pulsed time-of- flight laser rangefinding systems is typically +/- 1.5 mm in a dynamic range of 1:4-6. This is generally not sufficient, and additional gain control is obtained using a mechanical iris diaphram or variable density filter. Since the gain control bandwidth achieved in this way may not be sufficient for fast applications such as the measurement of paper sheet flutter in printing presses, for instance, a system of high speed automatic gain control electronics (AGC) with a three level structure is described here which consists of a PIN diode attenuator, an APD bias voltage control system and a constant fraction timing discriminator.