An Approach to Active Sonar Suppression Using a Dynamic Interference Model
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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This report summarizes preliminary work in the suppression of interfering active sonar for enhancement of underwater transients. The active sonar is modeled as an amplitude-modulated and frequency-modulated chirp signal. The estimation and suppression of the AM-FM chirp is performed in the framework of an analysissynthesis technique that is based on a sine-wave representation of signals with components characterized by time-varying amplitudes, frequencies, and phases. Parameters of the chirp model, estimated within the sine-wave analysis, are used to reconstruct a chirp over short-time intervals, according to its dynamics. The contribution of the chirp is then subtracted from the sine-wave components of the received signal i.e., the sum of interfering signal and desired transient, and the enhanced signal is obtained by sine-wave synthesis of the remaining contribution due approximately to the transient. Significant interference suppression is obtained because chirp dynamics are preserved over short time segments.
- Acoustic Countermeasures