ADAPTIVE RADAR TECHNIQUES FOR IMPROVING CLUTTER SUPPRESSION AND DETECTION OF LOW CROSS SECTION TARGETS

AIRBORNE RADARS FOR THE DETECTION AND TARGETING OF LOW CROSS SECTION GROUND VEHICLES MUST TRANSMIT MORE POWER, USE LARGER ANTENNAS, AND/OR OPERATE AT SHORTER RANGES TO ACHIEVE THE REQUIRED SIGNAL-TO-NOISE RATIOS. IN ADDITION, A MAJOR IMPROVEMENT IN SUBCLUTTER VISIBILITY IS REQUIRED. THIS PROPOSAL DESCRIBES A METHOD OF SIGNIFICANTLY IMPROVING THE SUBCLUTTER VISIBILITY OF SPACE-TIME ADAPTIVE RADARS AT THE COST OF INCREASED DIGITAL SIGNAL PROCESSING. UNDER THE PROPOSED EFFORT, THE ASI COMPUTER SIMULATION OF SPACE-TIME ADAPTIVE RADAR WILL BE EXTENDED TO INCLUDE AN ADDITIONAL DIMENSION OF ADAPTIVITY. THE PROGRAM NOW SIMULATES SEVERAL DIFFERENT RADAR/SIGNAL PROCESSOR ALGORITHMS FOR ADAPTIVELY CONTROLLING THE ANGULAR AND DOPPLER FREQUENCY RESPONSES OF THE SYSTEM. ADAPTIVE WEIGHTING OF CONSECUTIVE SAMPLES (TRANSVERSAL FILTERING) WILL BE ADDED TO THE SIMULATION, IN ADDITION TO THE PRESENT WEIGHTING OF ANTENNA OUTPUTS AND CONSECUTIVE PULSES. SUBBANDING WILL BE ADDED TO THE MODEL AND COMPARED WITH TRANSVERSAL FILTERING. THIS ADDITIONAL ADAPTIVITY WILL COMPENSATE FOR DISPERSIVE DIFFERENCES IN THE ARRAY ELEMENT PATTERNS DUE TO NEAR FIELD SCATTERING FROM THE AIRCRAFT STRUCTURE. BOTH THE ELEMENT PATTERN VARIATIONS WITH FREQUENCY AND INTERCHANNEL RECEIVER MISMATCHES WILL BE MODELED. THE PROGRAM WILL BE USED TO ESTIMATE THE IMPROVEMENT IN SUBCLUTTER VISIBILITY WITH THE ADDITIONAL ADAPTIVITY AND IN SYSTEM COMPARISONS. SIMULATION RESULTS WILL SHOW HOW MUCH ADDITIONAL CLUTTER REJECTION CAN BE OBTAINED WITH TRANSVERSAL FILTERING AND SUBBANDING IN SPACE-TIME ADAPTIVE RADARS. THE IMPROVEMENT IN RADAR CLUTTER SUPPRESSION IS NECESSARY FOR THE DETECTION AND TARGETING OF LOW CROSS SECTION GROUND TARGETS.