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By: - 21st December 2000 at 08:03 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
I don't understand why the system would have to be adapted to every external loadout. As far as I understand from the article (and others I've read) the only important factor is analysis of the incoming enemy radar pulse. The active ECM sends out an out of phase pulse to cancel the enemy pulse out, regardless of a/c configuration. Can you explain what you mean?
Ference.
By: - 21st December 2000 at 08:12 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
Their informations should be taken with care.
They are not even able to spell Rafale correctly.
By: - 21st December 2000 at 08:35 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
LAST EDITED ON 21-Dec-00 AT 08:39 AM (GMT)[p]Ference,
The article states that;
"Just how complicated it is to cancel a reflected radar signal can be seens from the fact that the original incoming signal from the radar will be reflected from many spots on the aircraft's body. Each spot will produce an individual reflection with its own, often unique, amplitude and phase. The amplitude of the reflection (high amplitude means that the relection would be easier to pick up than the one with lower amplitude) would depend on many factors, such as incident angle, particular type of material, geometrical form of a certain location on the aircraft's body that produced the reflectio and some other factors"
Now I'm thinking that not only would each store have it's own unique signature but also that they would interact with each other {as far as a radar waves are concerned} based on location and aspect angle. You can see the number of variables inherant, I'm wondering if the SPECTRA system can automatically compensate or if different load configurations have to be tested, certified and then programmed into SPECTRA?
torpedo,
That misspelling is fairly common, and I have seen this information elsewhere, it's just that this one explains it more in layman's terms.
By: - 21st December 2000 at 08:42 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
You're right, I have to admit I only read it briefly, must've missed that part. Sorry, you're right!!!
I guess they'll be checking radar signatures with every possible loadout. It's a big job, but not impossibly big. They just need one airframe for testing on a RCS pole or chamber, and after a few months/years of testing they have that data. That'll be before the bulk of a/c become operational.
Ference.
By: - 21st December 2000 at 13:42 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
Active radar cancellation certainly sounds like an interesting concept, but i'm think there will still be a gap between the radar waves hitting the aircraft and the ECM's ability to "mimic"
the wave. I still think the computers could not possibly be sooo powerful as to perfectly mimic the waves, putting them exactly in phase with the emitter radar's waves, although u never know what computer's can do these days.
MinMiester
By: - 21st December 2000 at 14:31 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
I think it is possible. This basic concept was proposed several decades ago, so they had some time to work it out.
Off course the computer needs time to analyse the signal before it can respond. So you'll have a short time when the radar signals will see the a/c, but if that time is short enough that will only be a few pulses, not enough to track an a/c and fire a missile.
Ference.
By: - 21st December 2000 at 14:40 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
I love this thread.
But IMHO it's not that easy : most modern radars are of the pulse compression type. That is they transmit a short wave which is modulated in amplitude. So the "wave pattern" is even more complexe. And you can shift not only the wavelenght but the modulation as you transmit,thus complicating the opponent jamming and probably making signal mimmic a inextricable problem.
By: - 21st December 2000 at 15:05 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
That is a good point. So in a way the jammer will always be one step behind the emmitting radar. If it changes pulse characteristics fast enough the jammer couldn't keep up. But still they ARE developing this type of jammer so somebody must have confidence in it, maybe that somebody knows of a factor we are overlooking.
Ference.
By: - 21st December 2000 at 18:05 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
Yes but one could think that they don't need to calculate the RCS of the aircraft for every position or in real time but only for a selected panel of flight profiles that the pilot (or autopilot) could adopt when facing a determined menace.
One could even imagine that these data were precaculated and loaded before take off with respect to the known threat.
For example if you know that your target is defended by a system you can't avoid you need to rely on active cancellation while if there is a SAM site on the path to the target you pass at distance it or fly behind relief.
By: - 21st December 2000 at 18:22 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
OK that's right
By: - 24th December 2000 at 02:54 Permalink - Edited 1st January 1970 at 01:00
RE: Active radar cancellation
I don't think that would be all that easy to do, SPECTRA has very high angular resolution and only the aircraft doing the emitting would likely be recieving return energy. The AC jammer itself is a solid state phased array, which in addition to being very precise may also possess LPI properties. I think the real problem facing AC is how to counter AESA tech radars, I don't see how they can pull that off...
Sorry Elp, all I've found is bit and pieces, as with the Rafale itself I suspect that the best of what little info available is in French.
Posts: 839
By: Rosco - 21st December 2000 at 02:57
Here's Interesting little article on how the Rafale's active cancellation system functions in principal. Other sources I've seen state that the system "performs as advertised" even in very demanding conditions.
What I'm wondering is if the system needs to be exhaustively tested and configured to each and every external loadout or if it can simply adapt on the fly? Rafale is appearantly second to only the F-22 in amount of onboard computing power, and it looks like it needs it!
Active Cancellation > http://www.geocities.com/CapeCanaveral/9735/rafale1.htm#*