High Precision Pulse Laser Ranging System Based On FPGA

The purpose of this paper is to design a high precision of pulse laser ranging system based on FPGA. Through the analysis of the performance index of the pulse ranging system, the paper designed a kind of pulse laser ranging system with the advantages of simple system, high precision, low cost, long measuring distance and strong anti-interference capability.The complete system solutions is put forward to reduce the rise time of laser pulse and the width of laser pulse, to increase the noise ratio of the receiving circuit and the accuracy of interval timing. The system mainly consists of three parts, including the pulse laser transmitting circuit and the high speed laser receiving circuit, and the high precision timing measurement on FPGA. The pulse laser transmitting circuit can provide high-quality laser pulse with the advantages of the high power and the narrow pulse width. Through the simulation test, the circuit can launch laser pulse with the properties of repetition frequency10KHz, peak current1.9A, pulse width50ns, raising time13ns. The high speed laser receiving circuit can amplify the weak current with high signal to noise ratio, and reduce the error caused by the deformation of Echo pulse through the timing-identify circuit with a constant ratio. The high precision timing measurement on FPGA consists of high precision time measurement unit, time calculation and storage unit, division unit and LCD interface unit. The high precision time measurement unit adopts the design of delay line. Delay line has accuracy of time255ps. Through the tool of chip planner and timequest, the time between the delay lines is further cut down by adjusting the distribution of the underlying. The time calculation and storage unit mainly completes the acknowledgement of the calculation point and achieves the calculation method. Through the simulation test, the error of the high precision time measurement module is0.2744ns.The distance error is4.12cm, and the high precision characteristic of the laser ranging system is guaranteed.