CHARACTERIZATION OF OWNSHIP DOPPLER AND TRANSMISSION CHANNEL PARAMETERS BY MEANS OF CLUTTER MEASUREMENTS

IT HAS BEEN FOUND, FROM EXPERIENCE GAINED ON THE CRITICAL SEA TEST (CST) AND THE LOW FREQUENCY ACOUSTICS (LFA) PROGRAMS, THAT THE ACOUSTIC ENVIRONMENT FOR LONG RANGE ACTIVE SYSTEMS IS UNIQUE. A PRINCIPAL CONCERN IS CLUTTER DISCRIMINATION, AND MANAGEMENT, AND ONE OF THE PRINCIPAL CLUTTER DISCRIMINANTS IS DOPPLER. IF ONE CAN ELIMINATE OWNSHIP'S MOTION, CLUTTER CAN BE CHARACTERIZED AS HAVING ZERO VELOCITY OR ZERO RELATIVE DOPPLER. THE FIRST ASPECT OF THE PROJECT PROPOSED HERE, IS TO USE CLUTTER ITSELF AS A MECHANISM FOR ESTIMATING OWNSHIP'S MOTION RELATIVE TO THE BOTTOM. THIS IS A NEW IDEA IN ACOUSTICS, BUT IT HAS BEEN USED IN RADAR (PARTICULARLY SYNTHETIC APERTURE RADARS) FOR MOTION COMPENSATION FOR SOME TIME. WE PROPOSE TO USE APPROPRIATE ADAPTATIONS OF SUCH TECHNIQUES, FOR ACTIVE ACOUSTIC SURVEILLANCE. ANOTHER USE OF CLUTTER STATISTICS WHICH WE PROPOSE, IS IN THE CHARACTERIZATION OF THE TRANSMISSION CHANNEL. THESE CHANNELS ARE CHARACTERIZED AS HAVING ATIME SPREADING FUNCTION. FOR SOME CHANNELS THE SPREADING RESULTS IN DISCRETE MULTIPATHS TO AND FROM A GIVEN RANGE, FOR OTHERS THE TIME SPREADING IS NOT RESOLVED INTO DISCRETE MULTIPATHS BUT IS MORE A CONTINUOUS FUNCTION. WE HAVE DEVELOPED TECHNIQUES WHICH USE THE CLUTTER STATISTICS TO FORM ESTIMATES OF THE TIME SPREAD FUNCTION VERSUS RANGE.