Patent ID: 6847588
Filing Date: 2005-01-25
Classification: G01S,G01V,G10K

Abstract:
1. A method for processing sonar information from an underwater hydrophone array, which array has a known spacing between adjacent hydrophones, at frequencies having wavelengths less than two times a spacing between adjacent hydrophones, the method comprising: a) providing an underwater hydrophone array comprising a plurality of receiver hydrophones, which array has a known length and known spacing between adjacent hydrophones, wherein λ b) providing forward motion for the hydrophone array underwater with a vessel at a velocity of the hydrophone array in water V c) selecting a synthetic upper frequency f d) defining a synthetic hydrophone spacing Δd e) determining the time interval for the hydrophones to travel the distance of the synthetic hydrophone spacing; f) calculating the number of sonar signal wavefronts predicted to be encountered by each hydrophone in the time interval for the hydrophones to travel the distance of the synthetic hydrophone spacing; g) selecting a telemetry sampling rate for the predicted number of sonar wavefronts, wherein the telemetry sampling rate is selected such that each wavefront is sampled more than once; h) detecting samples of a first sonar wavefront with each of the hydrophones at a time t i) detecting samples of N subsequent sonar wavefronts with each of the hydrophones at ≧2N equally spaced times in a time interval Δt; summing and recording the samples from each of the hydrophones with a beamformer to provide beam sets for the number of samples taken in the time interval Δt; and j) combining the beam sets into an assembly of beams at a time t