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In article ,
Hobo wrote: This NG loves to talk about whether or not stealth aircraft can be detected. What about the issue of detecting SAM radar? If LPI, or Quiet Radar techniques are used on the ground radars guiding SAMs this will make it difficult to find and destroy the radars. The problem with LPI is that most of them are just very low power, continuous-wave radars with a huge chunk of signal processing gear tacked on. Smaller output, harder detection, right? Except that defensive measures are getting better, too, for the same reasons, and with that low power, jamming becomes much easier. And if you get the power low enough, a cheap, disposable white-noise jammer takes the whole thing out of the equation (most LPI sets are pretty darned close to the noise threshold to begin with, which is what makes them hard to detect). Even with frequency hopping or broadband techniques, you're still broadcasting a signal of *some* sort, and the smarter ECM systems will still find you. -- cirby at cfl.rr.com Remember: Objects in rearview mirror may be hallucinations. Slam on brakes accordingly. |
#2
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![]() "Hobo" wrote in message ... I tried asking this question before and got zero responses;( This NG loves to talk about whether or not stealth aircraft can be detected. What about the issue of detecting SAM radar? If LPI, or Quiet Radar techniques are used on the ground radars guiding SAMs this will make it difficult to find and destroy the radars. Similarly, if the same pseudo-random noise techniques are used for the datalink the SAMs guidance will be harder to jam. If one cannot bomb SAM radar or jam the datalink than flying in enemy airspace becomes vastly more difficult. The basic ideas behind LPI radar seem to come from the same information theory behind much of the cell phone industry so the knowledge base is widespread. Most modern SAM guidance techniques are heading towards an active homing system. The French have a common active hommer on the AAM mica and the SAM aster. The SAM is launched preloaded with the co-ordinates and velocity of the target and the missile guides itself using an inertial guidance system to the vicinity of the target at which point the radar lights up. Usually a data link is also available for midcourse corrections. In the case of AMRAAM there is I believe only 1 midcourse update provided if at all. In this way: 1 The command link can be of low bandwidth and is easily given the characteristics of security and LPI. It is not neccesary to provide feedback to the missile since it has an inertial guidance system. 2 Little warning is given since there is no tracking and illuminating radar 'spiking' the target. 3 Jamming and stealth against the missile is less effective as the radar's illuminating power increases as the missile active radar approaches. 4 Multiple missiles can be launched. The next stage of radar appears to be impulse radar. This AFAIKS requires cryogenics. It consists of sequences of impulses of around 1 wavelength that contain broad spectrums of frequencies that can excite any resonance's within a stealth structure. It also is extremely capable of resolving chaff or terrain like ocean waves and ripples. |
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The problem with LPI is that most of them are just very low power,
continuous-wave radars with a huge chunk of signal processing gear tacked on. Smaller output, harder detection, right? As long as you use radar,or any kind of EM energy as a binary detection method,right. But if you start processing,for example, polarimetric data,you can easily seperate signals reflected by man made objects from the others. |
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#5
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And signals of any polarization are easy enough to generate with jamming
equipment, so if you're relying on that, you've got to worry about being spoofed. So,ECM,predicted to be dead after arrival of stealth platforms are "in" again. |
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#7
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In article ,
Hobo wrote: Great. Now what if the SAM radar is undetectable? No such thing. If it emits, it's detectable. -- cirby at cfl.rr.com Remember: Objects in rearview mirror may be hallucinations. Slam on brakes accordingly. |
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