The Air-born Blue-green Laser Radar For Water Depth Information Acquisition And Processing Methods Research

Airborne blue-green laser radar can not only measure the water depth, bottom mapping, underwater target detection (e.g., mines, schools, etc.), but also measure efficiently, operate simply and cost lowly. Foreign research on it is relative early and they have been developed the blue-green laser radar underwater detection system with some problem such as low accuracy and difficult to tell target signal. The study of airborne blue-green laser radar in China starts later than the west, and now is still in the stage of laboratory research and analysis phase. The difficulty to research the airborne blue-green laser underwater detection system mainly lies in the absorption and scattering properties of sea water. The absorption property of water would cause serious laser pulse signal attenuation, and the scattering characteristics of water will cause a lot of backscatter signal noise. The energy of noise signal generated by backward scattering is very high, and the dynamic range is wide, which is easy to drown the target signal and increases the difficulty of target detection. We could improve the receiving power by increasing transmitting power, but when the transmission power increases, not only the target signal enhanced but also the backscatter signals enhanced, so how to reduce the noise of target backscatter signal becomes the research emphasis of this paper. A new method based on microwave radar technology and blue-green laser technology has been proposed to solve the problem. The basic principle of this method is that in transmitting terminal, microwave signal carried on blue-green laser by amplitude modulation technology, and then transmits through water, reflect by sea bottom and get microwave signal by amplitude modulation demodulation signal at the receiving end, eventually uses mature microwave signal processing technology to process the receiving signal by correlation calculation, so that we could restrain the backscattering of sea water, enhance target contrast and obtain depth signal. The paper verifies the effectiveness of the technology through the simulation experiment at last.