Study Of Narrow Pulse Laser Detection Based On High Speed Sampling

Narrow pulse laser detection achieves long-range target detection using laser pulse with low divergent beams. By measuring the flight time of the laser pulse, distance information can be obtained. Moreover, it can be obtained from a single pulse measurement, and dynamic target can also be detected. Furthermore, pulse laser has high peak power which makes it possible for large distance detection in the absence of cooperation target. Therefore, pulse laser detection is widely used in military, industrial, civil, engineering and transportation field.In this paper,narrow pulse laser detection algorithm is studied based on the high-speed sampling. Firstly, theoretical models has been built and analysised including the laser emission, reflection characteristics, goal of laser propagation in atmosphere, echo signal of laser detector and pulse timing discrimination algorithms. The simulation software for estimating clutter discrimination algorithms is presented. Using this software, a new compound pulse detection algorithm is developed. This new algorithm combines matched filter algorithm and constant fraction discrimination(CFD) algorithm. Laser echo pulse signal is firstly processed by matched filter algorithm. After the first step, CFD algorithm comes next. Then, a hardware platform is set up processing data reflected by target. The hardware platform includes a laser diode, a laser detector and a high sample rate data logging circuit. The laser diode transmits short laser pulses at 12.5 kilohertz pulse rate and at 905 nm wavelength. An analog-to-digital converter chip(AD9467) integrated in the sample circuit works at 250 mega samples per second. FPGA chip is the master control chip for the laser pulse emission, the high-speed sampling chip control and the new algorithm. Finally, after the detection system tested, test result analysis and algorithm analysis is completed. The test analysis result demonstrates that the new algorithm realized the high speed processing and high speed sampling data transmission, and achieved 0.3m distance detection precision; the algorithm analysis result presents that the new algorithm achieves the best effect in range detection. Algorithm analysis result is consistent with the theoretical simulation.