Electronic Counter-CounterMeasures (ECCM)
Electronic Counter-CounterMeasures (ECCM) is the method by which you endeavor to combat the ECM systems of the enemy by either making your equipment ECM-resistant or by using techniques to nullify his jamming and/or decoy systems. It is an extremely sensitive area in that any disclosure of ECCM measures designed into a system is likely to inform the enemy of its vulnerability to ECM.
Against jamming systems, the most commonly used method is frequency agility, whereby the transmissions are made to “hop” over a large frequency band in a random fashion. This means that either the jammer has to spread its power over the entire band with the inevitable loss of strength on any particular frequency, or it must attempt to follow the signal as it hops randomly.
The latest technique is the use of “stealth” techniques to combat the radar system. This is beginning to be employed in aircraft and consists of several methods to reduce the radar cross section of the aim. The main techniques employed are
- to design the airframe itself to avoid sharp corners and flat surfaces which act as radar reflectors, and
- the use of radar-absorbent material which minimizes the amount of energy reflected back to the radar.
At the aircraft, the most important parts of the fuselage can be covered in radar-absorbent material to make it extremely difficult to detect.
Many anti-radiation missiles have been developed. The missile is passive in operation so that it cannot be picked up by ESM systems, and normally locks on to the sidelobes of the radar transmission. The main countermeasures against this type of missile are low sidelobes, frequency agility, and the use of decoy transmitters which must be positioned close enough to the surveillance radar to “seduce” the missile but not so close as to endanger the main system.