Estimation of motion parameters of underwater acoustic targets by combining Doppler shift and interference spectrum

Common moving targets in water radiate continuous spectrum noise and linear spectrum noise, and continuous spectrum noise forms interference fringes between light and dark in a shallow waveguide. According to the interference fringe, the ratio of the range at the closest point of approach to the speed can be obtained, but the two parameter values cannot be solved directly. Aiming at the problem that the speed and the range at the closest point of approach cannot be estimated separately by interferometric fringes, a motion parameter estimation method combining Doppler frequency shift and interference fringes is proposed. The parameter coupling curve of the speed and the range at the closest point of approach is obtained according to Doppler frequency shift of single line spectrum. Besides, the parameter ratio line can be obtained by the interference fringe. And the two-parameter estimation result can be illustrated by the intersection point of these two curves. Numerical simulation estimates the speed and the range at the closest point of approach of the sound source, and the average estimation error is 0.71% and 0.87% under the condition of the signal to noise ratio of 6dB respectively. The method was applied to the sea experiment data of Dagong Island in June 2021, and the average errors of the target motion speed and the range at the closest point of approach were estimated to be 2.5% and 4.4% respectively, which proved the effectiveness of the method.