PHASE-DIFFERENCE METHODS IN UNDERWATER ACOUSTIC SIGNAL PROCESSING

摘要

The application of phase-difference methods of signal processing in underwater acoustics is considered. These methods can be successfully used for processing of broadband complex signals from multi-element array in a multi-path channel with random Doppler frequency shifts and stochastic phase fluctuations. The algorithms based on phase-difference methods can be non-sensitive to stochastic phase and frequency variations. The application of phase-difference phase methods for processing of broadband signals from a multi-element acoustic array is considered. The methods based on the phase difference of impulse response estimation from different elements of acoustical array can be used for long term accumulation of this estimation in the case of the random Doppler frequency shifts. The difference of phases from impulse response estimation of neighbor elements for the signals of reclined underwater channel rays can be used for the estimation of the form of a flexible acoustical array. This estimation was successfully applied for the correction of the results of acoustical field measurements by multi-element acoustic array in international experiment THETIS-II in Mediterranean Sea (the voyage of research vessel "Akademik Sergey Vavilov", summer 1994). The synthesis of broadband signal invariant to Doppler frequency shifts and random phase fluctuations in multi-path channels is the another application of considered methods. Such broadband signals can be used for communication and positioning in the high frequency multi-path mobile acoustic channels with the great Doppler frequency effect. The energy of these signals received from a number of paths with the different Doppler frequency shifts in each path can be summed pseudo-coherent and accumulated on a long interval of time. Such signals were successfully used in the remote control communication for acoustical releases and controlled buoyancy underwater buoys.