THE GOAL OF THE ADAPTIVE RADAR COUNTERMEASURES (ARC) PROGRAM IS TO DEVELOP THE CAPABILITY TO COUNTER ADAPTIVE RADAR THREATS IN TACTICALLY RELEVANT TIME FRAMES BASED ON OVER-THE-AIR OBSERVABLE SIGNALS. AN ADAPTIVE THREAT IS DEFINED AS AN ADVERSARY S RADAR WHOSE WAVEFORMS AND BEHAVIORS ARE NEW, UNKNOWN, OR AMBIGUOUS. THREATS OF PARTICULAR INTEREST INCLUDE GROUND-TO-AIR AND AIR-TO-AIR PHASED ARRAY RADARS CAPABLE OF PERFORMING MULTIPLE FUNCTIONS (E.G., SURVEILLANCE, CUED TARGET ACQUISITION, TRACKING, NON-COOPERATIVE TARGET IDENTIFICATION, MISSILE TRACK, ETC.) AND EXHIBITING A HIGH DEGREE OF AGILITY IN BEAM STEERING, WAVEFORM, AND COHERENT PROCESSING INTERVAL (CPI) CHARACTERISTICS (E.G., CODING, PULSE REPETITION INTERVAL [PRI], ETC.).