The Research Of The Sheltered Target Imaging Using Chirped Amplitude Modulation Ladar Based On GM-APD

Laser radar have a wide applications in the accurate tracking, targeting and positioning, communications, detection, atmospheric research and so on, so it has become the focus of research in the field of high technology. However, many different tasks of the modern military war, such as the investigation of the unmanned aerial vehicle, missile guidance and so on, are affected by the shelter. This makes we couldn't find high value target timely and correctly, which will weaken the fighting capacity of our army greatly. Since the system of Chirped Amplitude Modulation Ladar based on Gm-APD detector came up, it had shown good detecting sheltered target ability in many experiments. This paper mainly researches the range accuracy of Chirped AM Ladar based on Gm-APD. Based on that, this paper researches the sheltered target detecting.Firstly, this paper investigates the current research situation about Chirped AM Ladar based on Gm-APD and makes clear the significance and purpose of this study. Based on that, the main research content of this paper is confirmed.Secondly, this paper research the operational principle of Chirped AM Ladar based on Gm-APD deeply. Due to the dead time of Gm-APD limits the sampling frequency increase and frequency modulation bandwidth expansion, which limits the range accuracy increase. This paper uses the minimum variance unbiased estimation method to deal with the intermediate frequency signal. The research result shows this method can improve the range accuracy effectively.Finally, this paper researches the sheltered target detecting. According to the different sheltered situation, soft shelter and hard shelter are separated: for soft shelter situation, the threshold method is used to extract the signal of the sheltered target; for the hard shelter situation, the maximum value filtering the shelter method and the second derivative extracting the sheltered target method are employed to pick up the interested targets. The simulation result shows that these two methods have good ability of detecting the sheltered target.