PASSIVE SENSING USING ELECTROMAGNETIC ARRAY

SENSITIVITIES IN MAGNETIC AND LOW-FREQUENCY ELECTROMAGNETIC BANDS HAVE BEEN LIMITED BY AMBIENT NOISE. SENSORS ARE AVAILABLE WITH EXTREMELY LOW NOISE LEVELS (ABOUT FIVE ORDERS OF MAGNITUDELOWER THAN THE AMBIENT NOISE). WE PROPOSE TO USE SUCH SENSORS IN AN ARRAY CONFIGURATION WHERE IT IS POSSIBLE TO OBTAIN SENSITIVITIES APPROACHING THOSE OF THE SENSORS THEMSELVES. ALGORITHMS FOR SUCH NOISE CANCELLATION HAVE BEEN DEVELOPED, AND DURING PHASE I WE PROPOSE TO DEMONSTRATE THE FEASIBILITY OF THE NOISE CANCELLATION SCHEME IN AN EXPERIMENTAL FIELD. REMOVAL OF THE LARGE NOISE FIELD WILL ALLOW LARGE INCREASE IN SENSITIVITY AND CONSEQUENT INCREASE DETECTION RANGE FOR VARIOUS TARGETS. THE SCHEME ALSO ALLOWS TRACKING AND POSSIBLE IDENTIFICATION FROM THE NATURE OF THEIR RESPECTIVE EMISSIONS. AN EXPERIMENT USING ONLY THREE MAGNETOMETERS AND A GROUND VEHICLE IS PROPOSED DURING PHASE I TODEMONSTRATE THE FEASIBILITY OF THE SCHEME. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - PROPOSED MAGNETIC ARRAY SCHEME WILL HAVE SEVERAL COMMERCIAL APPLICATIONS THAT INVOLVE EARTH RESOURCE SURVEY, GEOPHYSICAL MONITORING, ETC. MOST SIGNIFICANT APPLICATION IS THROUGH VARIOUS DOD AGENCIES. THE CONCEPT COULD BE USED FOR DETECTION, TRACKING AND IDENTIFICATION OF VARIOUS OBJECTS RANGING FROM MINES TO MISSILES.