Solomon Islands intervention force

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.


--
A: top posting

Q: what's the most annoying thing about Usenet?

On Fri, 1 Aug 2003 14:54:31 +0100, (phil hunt)
wrote:

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?
The Self Projection jammer pods often represent more than the
available lift capacity of the UAV unless you are talking about
something the size of a Predator or a Global Hawk...

I would guess the radar uses a different "chirp" for each pulse it
sends out; is that correct?
It may, but more likely it is a mono pulse, same chirp, but broadcast
on a different frequency each time...

(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.


(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).
While it could be done, it isn't all that cost effective, to build an
emitter that would look enough like a real radar to be attacked would
probably cost 15-20% of the price of the real thing. That's a lot of
money to spend on decoys!
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.
Depends upon what you are looking for. At fair amount of effort has
gone into reducing both the RF and Visual 'cross section' of aircraft.
A great deal of effort has also gone into reducing exhaust gas
temperatures. You can actually hold your hand in the exhaust stream of
an AH64 Apache while the engine is at idle.

If you are looking for an F4 or a B52, it won't be very hard, it is
big, noisy and smokey. If you are looking for a 100kg UAV at 5000
feet, or a Proteus at 70,000 feet... good luck... one of the reason
sat links are preferred is they only radiate energy upward, so they
don't provide much to listen for from the ground.

Really interesting this evolution of UAV's and other weapons such as JDAM
munitions.
How do the JDAM munitions work? Is it and inertia launch then initial GPS
guidance and an infra-red image for the last stage to home in on.
If a UAV and JDAM weapon where combined that would have to be a fairly
stealthy target?

Is it fairly easy to have a sensor that warns of overhead SAR from a UAV or
such.
Whats the difference between Synthetic Aperture Radar and just radar?
Is there any such thing as active infra-red or is infra-red solely a passive
means of detection. What's its range?

What's the formula for roughly working out the horizon of a radar?
Height in feet squared is the horizon in miles or something.
This new Surface Wave Radar blows it all out of the water.

"matt weber" wrote in message
...
On Fri, 1 Aug 2003 14:54:31 +0100, (phil hunt)
wrote:

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?
The Self Projection jammer pods often represent more than the
available lift capacity of the UAV unless you are talking about
something the size of a Predator or a Global Hawk...

I would guess the radar uses a different "chirp" for each pulse it
sends out; is that correct?
It may, but more likely it is a mono pulse, same chirp, but broadcast
on a different frequency each time...

(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.


(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).
While it could be done, it isn't all that cost effective, to build an
emitter that would look enough like a real radar to be attacked would
probably cost 15-20% of the price of the real thing. That's a lot of
money to spend on decoys!
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.
Depends upon what you are looking for. At fair amount of effort has
gone into reducing both the RF and Visual 'cross section' of aircraft.
A great deal of effort has also gone into reducing exhaust gas
temperatures. You can actually hold your hand in the exhaust stream of
an AH64 Apache while the engine is at idle.

If you are looking for an F4 or a B52, it won't be very hard, it is
big, noisy and smokey. If you are looking for a 100kg UAV at 5000
feet, or a Proteus at 70,000 feet... good luck... one of the reason
sat links are preferred is they only radiate energy upward, so they
don't provide much to listen for from the ground.

"M.R." wrote in message
u
Really interesting this evolution of UAV's and other weapons such as
JDAM munitions.
How do the JDAM munitions work? Is it and inertia launch then initial
GPS guidance and an infra-red image for the last stage to home in on.
If a UAV and JDAM weapon where combined that would have to be a fairly
stealthy target?

Current JDAMS are pure GPS -- no IR seeker. The weapon isn etirely passive
and certainly could be stealthy. The problem is that even the 500-lb JDAM
is really too big for current UAVs. Smaller bombs are in development, and
we may well see UAVs armed with them in the not-too-distant future.

--
Tom Schoene Replace "invalid" with "net" to e-mail
"If brave men and women never died, there would be nothing
special about bravery." -- Andy Rooney (attributed)

"Thomas Schoene" wrote in message
nk.net...
"M.R." wrote in message
u
Really interesting this evolution of UAV's and other weapons such as
JDAM munitions.
How do the JDAM munitions work? Is it and inertia launch then initial
GPS guidance and an infra-red image for the last stage to home in on.
If a UAV and JDAM weapon where combined that would have to be a fairly
stealthy target?

Current JDAMS are pure GPS -- no IR seeker.

They are INS/GPS guided and also have an INS only mode as a failsafe against
GPS jamming.

The weapon isn etirely passive
and certainly could be stealthy. The problem is that even the 500-lb JDAM
is really too big for current UAVs. Smaller bombs are in development, and
we may well see UAVs armed with them in the not-too-distant future.

The Small Diameter Bomb was due to be deployed in around 2006 i think. The
250lb weapon would be ideal for fitting to smaller platforms such as UAVs -
the probuction X-47, if there is one, would be able to carry a number of
them - and they have a high penetrating power fora small weapon. Looks
like it could be a good weapons system.

--
Tom Schoene Replace "invalid" with "net" to e-mail
"If brave men and women never died, there would be nothing
special about bravery." -- Andy Rooney (attributed)


BMFull

"Ben Full" wrote in message

"Thomas Schoene" wrote in message
nk.net...
Current JDAMS are pure GPS -- no IR seeker.

They are INS/GPS guided and also have an INS only mode as a failsafe
against GPS jamming.

You're right, of course. I meant only that they have no terminal imaging
seeker.

--
Tom Schoene Replace "invalid" with "net" to e-mail
"If brave men and women never died, there would be nothing
special about bravery." -- Andy Rooney (attributed)

On Fri, 01 Aug 2003 20:34:07 -0700, matt weber wrote:

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

The Self Projection jammer pods often represent more than the
available lift capacity of the UAV unless you are talking about
something the size of a Predator or a Global Hawk...

Why would it need to be so big? Is it the receiving equipment, the
transmitting equipment, or the electronics in between that takes up
the space?

(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).

While it could be done, it isn't all that cost effective, to build an
emitter that would look enough like a real radar to be attacked would
probably cost 15-20% of the price of the real thing.

How much do real radars cost?

Certainly there are some radio transmitting equipments that are
cheap -- for example mobile phones and wi-fi stations -- and I'd
imagine that scaling up the transmitting powrer on such a device
would be too expensive either.

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.

Depends upon what you are looking for.
[...]
If you are looking for an F4 or a B52, it won't be very hard,

That's exactly the sort of thing I had in mind (or an F-16 or
Tornado or F-22, etc, bascially any modern supersonic aircraft)

--
A: top posting

Q: what's the most annoying thing about Usenet?

On Wed, 6 Aug 2003 02:31:28 +0100, (phil hunt)
wrote:

On Fri, 01 Aug 2003 20:34:07 -0700, matt weber wrote:

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

The Self Projection jammer pods often represent more than the
available lift capacity of the UAV unless you are talking about
something the size of a Predator or a Global Hawk...

Why would it need to be so big? Is it the receiving equipment, the
transmitting equipment, or the electronics in between that takes up
the space?
All of the above, you need a receiver that can receive almost
anything, and enough electronics to be able to analyse the
transmission in real time (which requires very FAST A/D, identify the
characteristics of the emitter so they can be matched against the
threat library, and then you need a transmitter of sufficient power
and ability to generate an appropriate rep rate and modulation scheme
to be able to jam the threat, if it is a threat. All up, if you are
lucky, perhaps only a few hundred Kg...

(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).

While it could be done, it isn't all that cost effective, to build an
emitter that would look enough like a real radar to be attacked would
probably cost 15-20% of the price of the real thing.

How much do real radars cost?
Depend upon how fancy you want to make them. The military is famous
for 'gold plating', and what you have now is a computer that happens
to have a radar attached. Some of them have 8 figure price tags, the
problem is in producing an emitter that will be identified as a
potential threat, it really has to produce an output that looks like a
threat, which means you probably need just about the entire transmit
package.

Certainly there are some radio transmitting equipments that are
cheap -- for example mobile phones and wi-fi stations -- and I'd
imagine that scaling up the transmitting powrer on such a device
would be too expensive either.
Those however are very simple emitter that don't depend upon complex
modulation schemes, fast frequency hopping, or monopulse designs...
The bind is that todays ADF and Fire Control Radars control radars are
depend upon complex modulation schemes to extract a great deal of
information. For example they can tell the difference between a
737-200 and a 737-300, a helicopter and similar weight jet fighter,
and it isn't based upon the strength of the radar reflection, it is
based upon the assortment of doppler shifts they see in the return,
they really can see the fan on the engine, the rotor on the
helicopter, and propeller...

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.

Depends upon what you are looking for.
[...]
If you are looking for an F4 or a B52, it won't be very hard,

That's exactly the sort of thing I had in mind (or an F-16 or
Tornado or F-22, etc, bascially any modern supersonic aircraft)
Passive detections at this point is in two parts. At the moment only a
limited amount is done via EO, as a friend who in the business put it,
it is very limited because our heart really isn't in it. Otherwise it
is mostly based upon EMI that is generated on the other end. So if the
other aircraft is electrically quiet, and doesn't have a big visual
image, or create massive air flow disruptions, passive sensing won't
see very much.

Light the burners, or engage in some fancy maneuvers, or turn on the
search radar, and that is another story...

Passive detection is very useful if you have enough information, i.e.
if your threat library says that is a model XX-YY radar, and you know
those are only carried on a single type of airframe...