title: Clutter reduction using Doppler sonar in a harbor environment.
abstract: A high frequency experiment was conducted in the Woods Hole Harbor in Massachusetts to evaluate the effectiveness of Doppler sonar for discriminating targets from reverberation. Using a pulsed linear frequency modulated signal, one finds that the matched filtered outputs are filled with high-level discrete backscattered returns, referred to as clutter, which are often confused with the target echo. The high level non-target returns have an amplitude distribution that is heavy-tailed. Using a Doppler-sensitive binary-phase-shift-keying signal coded with an m-sequence, the target echo and clutter can be separated by Doppler and delay, and tracked using the Doppler spectrogram (Dopplergram). The Doppler filtered time series show a background reverberation with a Rayleigh-like amplitude distribution, with an improved signal-to-(peak) reverberation ratio compared with that without Doppler filtering. The reduced reverberation level with Doppler processing decreases the probability of false alarm (Pfa) for a given threshold level. Conversely, for a given Pfa, the higher signal-to-(peak) reverberation ratio implies a higher probability of detection. Transmission loss measurement was conducted to estimate some of the system parameters, e.g., the source level and target strength relative to the noise level.
authors.affiliation: Acoustic Division, Naval Research Laboratory, 4555 Overlook Avenue, Washington DC 20375, USA. tsihyang@gmail.com
authors.forename: T C
authors.initials: TC
authors.lastname: Yang
authors.forename: J
authors.initials: J
authors.lastname: Schindall
authors.forename: Chen-Fen
authors.initials: CF
authors.lastname: Huang
authors.forename: Jin-Yuan
authors.initials: JY
authors.lastname: Liu
mesh_terms: D003198:Computer Simulation; D004301:Doppler Effect; D008962:Models, Theoretical; D009038:Motion; D009716:Numerical Analysis, Computer-Assisted; D009792:Oceans and Seas; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014465:Ultrasonics / Q000379:methods*; D014732:Vibration