ANTI-JAM METHODS FOR RF RECEIVER

DETECTION, LOCALIZATION, AND CLASSIFICATION OF SUBMARINES IN ASW OPERATIONS CAN BE ACCOMPLISHED THROUGH THE USE OF AIR-DROPPED SONOBUOYS. ACOUSTIC SIGNALS SENSED BY SONOBUOYS ARE TELEMETERED BACK VIA AN RF LINK TO AN OVERHEAD AIRCRAFT FOR ASSOCIATED SIGNAL PROCESSING. HOWEVER, THE TELEMETRY PROCESS IS SUBJECT TO RELATIVELY UNSOPHISTICATED RF JAMMING WHICH CAN RENDER THE OVERALL SURVEILLANCE SYSTEM INEFFECTIVE. THIS PROPOSAL IS AIMED AT IMPROVING THE IMMUNITY OF SONOBUOY-BASED ASW SYSTEMS TO RF JAMMING THREATS. THE PROPOSED APPROACH IS TO UTILIZE AN ANTENNA ARRAY AND DIGITL PROCESSOR FOR AUTOMATIC SPATIAL NULLING OF RF JAMMERS. PAST WORK CONDUCTED BY ATLANTIC AEROSPACE IN RAPIDLY-CONVERGENT ADAPTIVE NULLING ALGORITHM DEVELOPMENT, HIGH -RESOLUTION DIRECTION FINDING FOR MULTIPLE COCHANNEL EMITTERS, AND REAL-TIME BEAMFORMING/NULLING BRASSBOARD DEVELOPMENT PROVIDES A STRONG FOUNDATION AND RELEVANT BASE FOR THE PROPOSED EFFORT. PHASE I WORK WILL DEFINE CANDIDATE SCENARIOS, QUANTIFY EXPECTED PERFORMANCE GAINS FROM SPATIAL PROCESSING, DEVELOP A JAMMER NULLING ALGORITHM WHICH AVOIDS ERRONEOUS NULLING OF THE DESIRED SIGNALS, AND SPECIFY A HIGH-LEVEL ARCHITECTURE FOR IMPLEMENTATION. THE BASIS OF THE APPROACH IS TO EXPLOIT A SERIES OF WEIGHT-AND-SUM ADAPTIVE BEAMFORMERS WHICH ARE APPLIED TO EACH NARROWBAND SONOBUOY CHANNEL.