Forum: General F-22A Raptor forum

Just to set the record straight, the 800 mile EODAS demonstration was aboard the Bac1-11 testbed, not CATBIRD.

http://www.es.northropgrumman.com/solut ... video.html

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wrightwing wrote:

river_otter wrote:

It will frequency hop almost at random 40+ times per second, and no jammer is going to be able to flood the sky with several MW of radar energy in each frequency slot across that whole spectrum simultaneously. In at least some frequencies the radar will hop to, the radar will illuminate the target's area of sky with a huge amount of energy against a zero background, and only the target will reflect an appreciable amount of that energy back. Huge signal plus very low noise equals massive advantage in detection range over the best possible IRST.

I agree with your conclusions, but the APG-77 hops freqs at >1000 per second, making it very difficult to jam. This is also one of the reasons why it works well for LPI too.

Thank you. I knew it was waaaay north of 40/sec but was too lazy to look up the actual public number. Better to be under than over.

Good point with the LPI, too. Unless you're the one emitting and you know the exact moment and frequency and output power of each beam, a sub-microsecond burst will look very much like thermal noise or background static in any system trying to detect it. Tune discrimination down to let your detectors "detect" the APG-77's LPI output, and you pick up so much other actual static and noise you still don't see the APG-77. I would not be surprised if the APG-77 and APG-81 were also not at all random in their frequency hopping, but actually listened for and tried to mimic the real background signals in their vicinity, making it even harder for would-be detectors to tell the difference.

Forum: General F-22A Raptor forum

IRST vs Raptor