Study On The Signal Processing Of Lidar

Since Duntley found blue-green window in ocean(from 450 nm to 580 nm band of blue-green within a lot smaller than other wavelengths of light decay), Mr. Hickman and Hogg demonstrated the feasibility of airborne lidar underwater target detection, opened the door for underwater detection by photoelectric technology, makes the airborne lidar underwater detection technique is becoming a hot spot of countries to study.Lidar underwater detection system which combines optical, mechanical and electrical is a complex system, so far in our country is still in the stage of laboratory research and experimental analysis.The basis of this article is based on the lab underwater detection technology, and deeply study signal processing technology of lidar underwater detection system, it can get some water quality parameters by the echo signal processing, multi-peak gaussian fitting, and improve the ranging accuracy.·This subject is used to improve the laboratory existing laser underwater detection system, mainly detection system of technology improvement.Using SPM array, the output signal will be send to the high-speed data acquisition and recording system after amplifying, filtering and other links, and be analyzed through the PC.The PC program can control acquisition of echo signal length and sampling frequency. This system can be as full waveform lidar.Based on the Monte Carlo method, we simulate the formation process of the echo signal, a detailed analysis of the optical transmission is processed.By setting some parameters to simulate different echo signal waveform. This method is helpful to study the effect of the result of echo depended on echokey environmental parameters, and also provide the theory basis for our bottom reflection extracted from forms of echo waveform signaBecause the system is full waveform lidar, the output signal is one-dimensional echo waveform. Based on the processing of echo signal, it can not only acquire the distance information of target,but also calculate the attenuation coefficient of water, target reflectivity information. Through multi-peak gaussian curve fitting of echo signal, we can get the laser pulse and the echo laser pulse of target, location, peak value, pulse width of each pulse information, as technical basis for subsequent target recognition.At the same time the accuracy is improved an order of magnitude through the multi-peak gaussian curve fitting.We can obtain the reflectivity information of each point on the surface of target through compare echo of laser pulse fitting of the target and laser pulse amplitude wave, and then display reflectivity information with pseudo color as the target of gray image, the gray information of different targets can be used to distinguish.It point out a method for seawater attenuation coefficient through the relationship between the attenuation coefficient.and diffuse attenuation coefficient which can be got through the digital processing of lidar echo signals.The method can measure the quality parameters of the large area of waters quickly, but the precision is not high, we need to correct the coefficient.