Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uwm.edu!linac!att!cbnews!cbnews!military From: rh@craycos.com (Robert Herndon) Newsgroups: sci.military Subject: Re: Radars in Fighters, AWACS, etc. Message-ID: <1991Mar22.044326.24054@cbnews.att.com> Date: 22 Mar 91 04:43:26 GMT Sender: military@cbnews.att.com (william.b.thacker) Organization: Cray Computer Corporation Lines: 57 Approved: military@att.att.com From: rh@craycos.com (Robert Herndon) Since the original article <1991Mar12.232220.29870@cbnews.att.com> mentioning that he thought an F-14 could turn off its radar and still see stuff on its radar screens from all the other radars around, I have seen two apparently knee-jerk "nope, can't be done" responses, and no positive responses. While certainly the task would be non-trivial, it is certainly not impossible, either, although the F-14's radar proper might not be running the radar screen. Such an ability would be most useful for many reasons. First, it means that most aircraft in a mission could maintain radio silence. This would help deny the enemy passively obtainable information on how many planes the flight contains, and what kind of planes the flight has (if planes other than the F-14 can also do this). Second, radar & ECM take power. Why waste it, even if you do have lots? ECM in particular requires pods which normally generate their own power from the airstream (read "drag"). Third, though there are probably other solutions for this, why clutter up the spectrum so much with every aircraft's radar? It is that much more junk the radar and ECM systems must notice and decide to ignore. As to how it can be done, I'm sure there are E&M, radar, and ECM persons who are much more familiar than I on this topic, but: 1) Every combat aircraft these days has multiple receiver antennas. Timing information correlated from three on a signal source gives notice and bearing, which in a dogfight situation is 80% of the battle. (viz. "Modern Air Combat"; in 80% of all fighter-fighter kills, the victim is taken unaware; only 20% occur after initial engagement has failed to produce a kill.) 2) If the emitter's characteristics are known to the receiver, then much more could be gleaned. If the emitter's frequency and velocity are known, doppler analysis should provide rate of closure; if its strength & relative position are known, then the strength of the reflection can provide approximate range/size information. It seems that if all characteristics of the emitter are known, then anything the radar can normally ascertain should be ascertainable. It also seems like there are lots of tricks that can be played to ensure that friendlies know emitter characteristics while unfriendlies don't; e.g., slave radar frequency-scan to the IFF transponder codes, so that friendlies can reliably ascertain information about the emitter, etc. Anyone with more knowledge care to comment? -- Robert Herndon -- not speaking officially for Cray Computer. Cray Computer Corporation 719/540-4240 1110 Bayfield Dr. rh@craycos.com Colorado Springs, CO 80906 "Ignore these three words."