The Method Research Of Underwater Continuous Laser Backscattering Measurement Based On Correlation Algorithm

After the analysis of the underwater transmitting properties of the blue green laser and the correlation properties of pseudo random codes, an underwater continuous laser backscattering measurement method based on correlation algorithm is proposed. The continuous blue green laser signal, modulated with pseudo random sequences, is used as the measuring optical signal. Some of the beam will be scattered back to the laser through backscattering procedures. After changing the backscattered laser signal into electric signal by means of photoelectric conversion, correlate the electric signal and the local pseudo random electric signal. The backscattering intrinsic curve can be obtained, which contains the water information. And through proper information acquisition method, the information of the water volume can be obtained.After analyzing and simplifying the multi-scattering model of underwater laser, an underwater laser equal phase model-equal phase volume is proposed. After the simulation and test work by Matlab, it shows that the results the model of the equal phase accords with the basic physical principles and has some important properties.Using different pseudo random m sequences will obtain different correlation maximum values, and as the increase of the progression, the maximum correlation values increases in square laws, but on the contrary, the correlation minimum values maintain the same. Using longer pseudo random m sequences will get larger correlation maximum values. And it can solve the problems of the rapid attenuation and weakness of the laser in the water, and meanwhile it can increase the largest non-fuzzy distance. This method provides an estimation method of the underwater laser backscattering, which can be an effective way for the water quality measurement and underwater detection.