Pulsed Laser Ranging Receiver Circuit Timing Method

A type of receiver circuit and timing circuit which can be applied in high-speed laser range-finder is discussed in this paper. In the experimental system APD transferred laser pulse to weak electrical current. After two-level amplification we got a voltage pulse that had a enough amplitude to be applied, the timing point was discriminated by the constant-fraction timing discriminator circuit. Timing circuits transferred the pulse flight time to digital signal accurately. Implementing normal time measuring method, flight time of pulse laser was multiplied and measuring speed was de-multiplied. To solve this problem, quick range measurement technology was researched based on the method of propagation delay and working principle of CPLD. A time measurement circuit with an accuracy of ?0.2m was designed and accomplished. It could finish the whole measurement process in 80ns after the bounced pulse was received. This circuit could be integrated in one chip of programmable logic device, so the area and power consumption was decreased and anti-interference ability was strengthened. If the object was more than 15m away, the measuring time of radar was determined by the distance of the objects. The content of this paper can be applied in three-dimensional laser image radar which scans on targets in high-speed.