Electronic Countermeasures (ECM)

Abstract

Because it finds and measures noncooperative targets, radar motivates various countering actions. Motorists might want to deprive the highway patrolman of information about their speed. Certainly, nations want to deny other nations all kinds of information, particularly in times of tension or war. An obvious way of denying radar information is to disrupt the very small amounts of received signal with spurious energy—either actively, by radiating energy in the radar’s frequency band (called “jamming” or “active ECM”), or passively, by dispensing various extraneous objects (called “passive ECM”). Both classes of ECM are aimed at obscuring the target or confusing or misdirecting the radar or its operator. In the United States military a culture has arisen which is based upon the development of ECM and responses to it (called “electronic counter-countermeasures,” ECCM). All types of electronic transmissions, not just radar, are involved. A national professional society, called the Association of Old Crows, thrives.