Radar Electronic Countermeasures in Stand-Off Task (Stand-Off-Jammer)
A Stand-off Jammer (SOJ) is a Jammer System installed on board a special mission airborne platform (or in one or more external PODs) with the purpose to reduce long-range radar coverage on friendly intruders, and consequently to delay their engagement, allowing the intruder package to enter in the enemy area.
A SOJ system is capable of automatically intercepting and processing received radio frequency signals.
Signals that will be identified and pinpointed also for Electronic Order of Battle (EOB) definition and SIGnal INTelligence (SIGINT) purposes.
Any consequent jamming action to interfere the received signals is automatically set up but, being a form of fire, has to be cleared by the operator to respect the rules of engagement.
Figure 1: Weapon Systems Detection Range reduction due to EA
There is a large variety of Electronic Attack techniques, which can be categorized as interference.
The objective of these techniques, known as noise jamming techniques or deception jamming techniques, is to produce an interference signal that masks the target signal in a way to hide it to the target radar (noise) or to confuse or overload the processing of the radar (deception).
Figure 2: Effect on Radar PPI of different Jamming Techniques
Since the SOJ is more distant from the radar than the platforms to be protected it receives the radar signal with a significant delay.
The jamming action must start before the reception of the radar signal, enough in advance to cover the radar echo of the planes to be protected with a limitation in the possible jamming techniques.
This implies that coherent techniques deception (DRFM based) can be done only in case of frequency stable radars; otherwise, for frequency agile radars, only non-coherent techniques (noise jamming) can be used.
With the correct balance of distance and power it is possible to reduce weapon system detection range more than 70% and weapon system azimuth coverage more than 20°of safe corridor (Fig.2).
Countermeasures often used to perform the Stand-Off Task are:
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Noise jamming Techniques:
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Barrage Noise
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Spot Noise
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Swept Noise
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Cover Pulse Noise
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Deception Techniques:
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Spoofing
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Multiple False Targets (MFT)
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