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US Army Developing Encrypted Radar Waveform (thestack.com)
An anonymous reader writes: The U.S. army is working on an innovative technology for masking radar emissions in contested territory and environments with heavily congested radio bands. Effective radar system performance is critical in military operations, yet remains a challenge in locations under attack or in areas of high traffic density. Army researchers have now developed a noise-encrypted radar waveform called Advanced Pulse Compression Noise (APCN), which can be tuned in real-time to allow users to adjust radar performance depending on their surroundings. Research scientist, Mark Govoni explained: 'Having the ability to transmit a radar waveform that's continually changing, one that never repeats itself, and looks like noise, is extremely difficult to intercept....and remains anonymous to radar detectors.'
If a spread spectrum signal is below the noise floor, there's no way of telling that it's even there unless you know the pattern.
Will this avoid lock? Probably not. I would imagine that attackers will just lock onto maximum noise rather than maximum signal. May make attacking radars harder though. And I suppose standing near an arcing power line in a war zone might be a bad idea if this becomes common.
BTW, are these things going to play hell with other radio communications?
Won't it make identification problematic though? The big misconception about RW (Radar Warning) sensors is that it they only identify hostile radiation sources when in reality you want to know exactly what is lighting you up even if it is friendly. This has led to some unfortunate incidents. During the Iran-Iraq war the Iranians actually lost some F-14s to Iraqi fighters because the Iranian F-14s had a standard NATO RW unit that did not register the radars of Iraqi Mirage fighters and their Super 530 BVR missiles as a threat. In Europe this was OK since French fighters were not a threat but in the gulf, not so much. I expect the Iranians quickly figured out to change the threat classification of French radar signatures to 'Hostile'. The consequence is that firstly, once all radiation sources on the battle field look like noise, all you'll be able to tell after that situation becomes the norm, is that you are being lit up by an unusually strong source of radio noise. You won't be able to tell if it is friendly or not. Secondly I expect the current crop of anti radiation missile can be fired at a radar source and then lock onto another one if the primary target goes dead or the missile gets confused. For that purpose it would have to do some form of IFF, presumably based on the output of some derivative of a bog standard aircraft RW sensor, like those Iranian F-14s had, so that it does not accidentally choose a friendly radiation source when it picks it's alternate target so if radiation sources, friendly or hostile, all look like noise and the AR missile just gets locked onto strong sources of noise it would be unable to identify the operator of any alternate radiation source and thus unable to choose an alternate target without risking a blue-on-blue incident. I expect that the ROE for engaging radiation sources would be tightened up pretty severely, especially when firing AR missiles at AWAC aircraft.