Experimental verification of bistatic active detection and propagation speed correction in shallow water with negative thermocline

In order to estimate the capability of bistatic active detection based on a stationary horizontal array and flexible source in shallow water environment,a bistatic active signal simulator is developed.Further,the transmission losses and energy spreading losses are analyzed and the capability of bistatic active detection in shallow water environment is estimated.An experiment was conducted in the South China Sea according to the predicted detection range.The bias between the selected reference sound velocity and the pulse propagation velocity of the target echo degrades the positioning accuracy.An approximate method for the pulse velocity estimation is proposed to reduce the positioning error caused by the bias.Experimental results show that bistatic active detection can effectively detect target in negative thermocline environment,the estimated SNR(Signal-to-Noise Ratio) with the simulator are reliable,and the positioning accuracy can be improved by using estimated pulse velocity.