Communications, Radar & Electronic Warfare (201.. - Index of

132 Commul11calion, Radar and Electronic WarfareCover jamming uses transmissi on of noise to raise the noise floor of the victimreceiver. Because the noise has no distinguishing features from noi se, it is difficult forthe vi cti m radar system to determine that it is beingjammed at all. This is si milar to thecase of communications jamming.As well as the active jamming techniques described, decoys are also used. Thisranges from the Penetration Aids (Penaids) used by ballistic mi ssile re-entry systems,in which mUltiple decoys indi stingui shable from the real warheads, to the use of chaffto produce false targets. These are described in Part Two.Table 7.2methodsCommon ECCM techniques and the part of the radar system used to counter jammingECM method counteredNoise False RGPO VGPO AngletargetstealingRadar sub-systemECCM methodAntenna Reduce sidelobes x xMonopulse angle trackingMinimise cross-polar responsexxSidelobe blanking x xSidelobe cancellationxElectronic scan x x xAdaptive receivepolarisationCross-polarisation cancellationTransmitter Increase power xPulse compressionFrequency diversityFrequency agIlity x xPRF jitter x xRPGO memory nullingReceiver Increase bandwidth x xBeat frequency detector x xCover pulse channel processingHome-on-jamLeading/trailing edge trackxxxxxxNarrowband doppler noise x xdetectorVelocity guard rate x xVGPO reset x xSignal processing Coherence processlI1g x x xCFAR x x xDoppler/range rate x xcomparisonTotal energy testxxx