Passive Sonar Signal Simulation In Time-Space Varying Environment

The fact that the passive sonar works in time-space varying environment causes the temporal and spatial changes of passive sonar signal. To provide the diversified and realistic simulation signal for array signal processing system, the passive sonar signal simulation methods in time-space varying environment are studied according to the working principle of the passive sonar. And the underwater array signal simulation system is developed on the TigerSHARC201 processor, which is implemented in real-time. The main work of the essay is as follows:The requirements and implementation methods of the sonar array signal simulation are studied and analyzed. The entire simulation system can be divided into several main modules including simulation of the moving target track, simulation of the target radiated noise, simulation of the underwater acoustic transmission channel, simulation of the array element signal and simulation of the ocean ambient noise.Due to the constant motion of the sonar target and platform, the working environ-ment of passive sonar system keeps changing, which contributes to the temporal and spatial varying characteristic of the passive sonar signal, including the nonstationary of target radiated noise, the significant Doppler frequency shift and the towed linear array shape distortion caused by sonar platform maneuvering.To improve the performance of the traditional simulation system when describing the temporal and spatial changes of passive sonar, the passive sonar signal simulation methods in time-space varing environment are proposed in this thesis. The parameter varying model, including time-varying spectrum level, continuous spectrum and line spectrum, is proposed to simulate the nonstable target radiated noise. To imitate the Doppler frequency shift caused by the relative motion of sonar target and plateform, the Doppler real-time simulation method based on precise time delay filter is invesitagated. Forthermore, the passive sonar simulation method using circle arc and sine is proposed to imitate the towed array shape distortion when ship maneuvering.Passive sonar signal emulation system is designed and build on TigerSHARC201 high speed parallel signal processing board. The entire framework of the system and the implementation method of each module are dicussed in the thesis. The system achieved real-time passive sonar simulation signal output when the acoustic environment changes in time and space. And the target and ocean characteristic of the system can be set according to different requirements. Finnally, the simulation performance of the system is verified through the analysis of the output data.