Non-Cooperative Bistatic Sonar for Underwater Environmental Monitoring: a Model-based Approach

In this contribution we consider the simplified bi-static case in which the source waveform is known, and in particular is a chirp signal of known duration and bandwidth. The unknown source position is estimated by exploiting the multi-path structure of the received signal, in particular by extracting the acoustic channel impulse response at the receiver (through matched-filter and automated envelope peak extraction) and matching it with the one predicted by a ray-tracing model [4]. Environmental parameters (bathymetry, sound speed profile) are assumed known. Not having knowledge of the emission time of the source signal, the impulse response matching is based on computing the difference in time between the first and the subsequent arrivals. Source position estimation is obtained by minimizing a measure of discrepancy between the measured and the predicted time-difference sequences as a function of source depth and range from the receiver.