On Thu, 31 Jul 2003 21:38:38 -0700, matt weber wrote:
On Thu, 31 Jul 2003 16:11:48 +0100, (phil hunt)
wrote:

On Fri, 25 Jul 2003 22:44:02 +1000, RT wrote:

The Raven wrote in message ...
My only concern is that the Aerosonde UAVs will be over hyped to the point
people will get the wrong impression of what they are and what they are
capable of.

Yair. Well.

Not helped by the hype on the Aerosonde web site rabbiting on about its
radar disruptive capabilities - shortly after saying the total power
available is 30 watts or similar. It's not my field but I have a severe
problem believing 30 W in a UAV will disable your average anti-aircraft/G-A
missile radar......

Why?

Couldn't the UAV check for radar emissions, and then broadcast a
signal on the same frequency the radar is using? wouldn't that
disrupt the radar?

Depends upon the type of radar. There is very little 'CW' radar in
use anylonger. most is "chirp" frequency modulated, so if you don't
appropriately modulate the signal, it is simply ignored.

That makes sense. How easy would it be for the UAV to listen to thre
incoming signal, and match its response to it?

I would guess the radar uses a different "chirp" for each pulse it
sends out; is that correct?

(Think about
why the AM radio hears the ignition noise on the cars as they go buy,

I can't say I've ever noticed that effect, but I'll take your word
for it.

but an FM radio does not. Ignition noise is amplitude modulated, and
FM detectors do not detect amplitude.

Others are monopulse. they fire a single pulse. The next pulse they
fire will be on another frequency. There are all sorts of modulation
and transmission schemes to extract additional information from the
target, and to make the radar more difficult to jam. EF-111's and
EA6-B use the entire payload for Electronic counter measures.

It seems to me the best way to counter a radar is to fire a missile
that homes in on the radar's signals -- since a radar, to work, must
emit signals.

(Of course, an adversary could build lots of cheap boxes that give
off signals that appear the same as a real radar, to soak up lots of
anti-radiation missiles).

This is why ECM system are so complex. To defeat the other radar
effectively, you have to figure out exactly what it is (and the USA
and it's allies have a long history is doing things to 'excite' the
air defenses of less than friendly countries so they can characterize
the radar, and build a threat library.

How good are passive sensors compared to radar? I would imagine that
visual light and infra-red would be quite good ways of detecting
aircraft (and if you have 2 detectors some distance away you can use
triangulation to get the exact position), at least when there are no
clouds.


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