Defense against UAV's

"Fred J. McCall" wrote in message
...
[ SNIP ]
I learned it the simple way: If you can see it, you can kill it.

Well, not if "it" is capering about merrily in a No Fire Area.

AHS

In article ,
says...

wrote in message
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Hint: Look up the accuracy specifications of GPS.

In 7-10 years it will be Galileo. The specifications are a little bit
eklastic as they depend on integration time. If you are talking about
RELATIVE separation this will in fact be only a few centimers, the
accuracy of DGPS.


The accuracy of the GPS systems isnt the issue anyway. Its
handling the problem of separattion of large numbers of drones.

If they have to communicate with each other that introduces
extra weight, a considerable processing issue and a vulnerability
to jamming and/or spoofing.

Frankly you'd probably be better off accepting a certain percentage
of losses due to mid air collisions


That's my position also. One of these days I'll have to set up a
Monte-Carlo simulation to try to judge the collision probability.
As it is, one of my customers still wants to have their autonomous
flying machines exhibit 'flocking and anti-collision' behavior.
Keeping track of where 49 other systems are and where they are
going IS a considerable processing issue---but you can simplify
by ignoring those that are more than 10 seconds flight away
from the system of interest.

Jamming and spoofing can be an issue---but it is somewhat difficult
to jam a spread-spectrum system that only has to communicate
a few hundred meters (from one drone to another).

Mark Borgerson

Keith W wrote:
wrote in message
oups.com...

Keith W wrote:
wrote in message
ups.com...


Hint: Look up the accuracy specifications of GPS.

In 7-10 years it will be Galileo. The specifications are a little bit
eklastic as they depend on integration time. If you are talking about
RELATIVE separation this will in fact be only a few centimers, the
accuracy of DGPS.


The accuracy of the GPS systems isnt the issue anyway. Its
handling the problem of separattion of large numbers of drones.

If they have to communicate with each other that introduces
extra weight, a considerable processing issue and a vulnerability
to jamming and/or spoofing.

Frankly you'd probably be better off accepting a certain percentage
of losses due to mid air collisions

Keith



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The issue of transmission is the ability of a controller to take
action.

You dont get it. To maintain separation each drone needs to know
where its neighbours are not just its own position

Also you need some degree of defense in depth. If an enemy
swarm approached you, you would need the ability to direct resources to
that are. One UAV with a LMG is not going to stop a swarm. If however
it had communication technoilogy it might.


The USN isnt going to rely on one LMG for defence

Acceptance of losses due to mid air collisions - OK there will be heavy
losses from a variety of causes. This is, of course, acceptable in a
cheap unmanned system.

To me the amazing thing is the sophistication of COTS. You talk about
weight and cost, but I can put a mobile in my shirt pocket which can do
the most amazing things. Spoofing - all converstaions are routinely
encrypted. Jamming - yes OK but if you are the US you simply put the
jammers out of action.


The US is doing the jamming in this scenarion and dont kid
yourself that encryption cant be broken.


In point of fact use of an error correcting code, such as Reed Soloman,
will go a long way to soving the problem of jamming. You transmit in
bursts, the jammers have be on all the time.


And this is a problem because ?

If you were to have a swarm of UAVs with slightly modified mobile
phones with some aircraft being base stations and commumicating via
satellite you would have gone a fair way to building your system
without too much reaearch.


Psst mobile phones require repeaters in line of sight, there arent
too many in the middle of the Gulf


Keith



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I think you misunderstand the concept. It is one LMG per plane not one
LMG. The whole concept rests on low cost, density and because of
density there will be line of sight communication, although not
necessariyy direct. Communication is of course needed to allow
concentration of forces. You can in fact visualize this as an army of
robots.

Encryption - can it be broken? There have been a number of mathematical
articles on this. If it is breakable you can simply use more bits. A
faster code is noltiplication in a modulus and exlusive OR, but you
need to transmit "die Radstellung" by another method (say RSA).

In article ,
says...
Mark Borgerson wrote:
In article ,
says...
Mark Borgerson wrote:
In article ,
says...
Jack Linthicum wrote:
[snip]

I think that a spread spectrum burst type transmission can be
intercepted and given a rough bearing. The money to do this is
miniscule in comparison with making Trident missiles into hand
grenades.
The command post does not move between transmissions. Spread
spectrum/frequency hopping systems return to previous frequencies every
few seconds. Just use several bursts to home in on the transmitter.

Why are you assuming that the command post does not move? I see no
reason that a mobile command post and multiple mobile transmitters
could not be used.

This comes down to the definition of mobile. If the command post stays
in the same place for half an hour it is static. A constantly moving
command post would need a vehicle the size of a bus to hold the
operators and long range transmitters, possible but hard to camouflage.

So you don't think the Iranians have buses or semi-trailers? Suppose
there are 100 semis on the coastal road. Which one do you target?

The one with the big aerial.

Small aerial to small aerial on moving objects gives a short range.

You can put a pretty large antenna (at 900Mhz or higher) inside the
back of a semi trailer. (Probably best to use fiberglass panels
rather than aluminum on the outside, though!)

Spread spectrum and frequency hopping systems do use a finite number
of frequencies---but the sequence of freqencies used may not repeat for
many hours. That leaves you with a broadband collection problem
and having to sort out multiple emitters on the same bandwidth with
different hopping schedules. I suspect that is a problem handled
offline and after-the-fact, and not in real time. However, the
technology has probably advanced a bit in the 30 years I've been
out of the sigint world. ;-)
If we are trying to destroy the command post we do not need to receive
the entire message we can simply wait until that frequency is reused by
that transmitter. If the equipment is hopping over 100 frequencies it
should be back within the next 200 transmissions.

With spread-spectrum transmitters, the time spent at one particular
frequency may be only a millisecond or two. If you can provide a link
to a system that can accurately track a moving spread-spectrum
transmitter, I'd be interested in reviewing its specifications.


Try
http://klabs.org/richcontent/MAPLDCon98/Papers/d3_haji.pdf

Thanks for the link. It looks very interesting. I couldn't find
any data on the angular resolution of the DF, though.


For DFing you do not need to accurately track a spread-spectrum
transmitter's hops. You only need to guess one of the frequencies.
To intercept and decode a signal you need (almost) all the frequencies,
providing it can tell the difference between static and modulated signal
the above machine may be able to reconstruct the signal by listening
on hundreds of frequencies simultaneously.

The problem with intercepting spread-spectrum signals is that the
receiver KNOWS where the next signal will arrive. It can tune it's
receiver software for that frequency. The intercept receive has to be
able to recieve ALL frequencies---and thus cannot use the same signal
processing techniques as a receiver that knows the sequence.
The computers will need programming to treat transmissions from two
widely separated locations as two targets. Home in on them one at a time.

How do you work with one continuously moving target transmitting on
256 different frequencies? I suppose it could be done with large
enough antennas and enough processing power on a number of different
ships. It's not going to be easy, cheap, or widely available, though.

You can deal with frequency hopping by listening on hundreds of
frequencies simultaneously. When one of the frequencies is known very
accurate direction finding equipment can tune to that frequency and wait
for the transmitter.

How accurate is 'very accurate'? Back when I was working with HFDF,
one or two degrees angular resolution was considered reasonable.
The system I worked with is described he

http://www.nrl.navy.mil/NewsRoom/images/75awards.pdf
(look at the award citation for high frequency direction finding)

Where the target is physically moving whilst transmitting something like
a radar display is needed. PCs can be programmed to act in this
fashion. Five years ago the army was working on things like this.


Mark Borgerson

"Jeroen Wenting" jwenting at hornet dot demon dot nl wrote in message
...

"Jim Yanik" wrote in message
.. .
wrote in
ups.com:

According to:

http://en.rian.ru/onlinenews/20060530/48833304.html

An Iranian UAV was able to circle a U.S. aircraft carrier undetected
for 25 minutes.

With U.S. forces making increasing use of UAV's, the inevitable
question becomes:

How can we protect our forces against UAV's when other countries or
terrorist
organizations start using them against us?


Was the Iranian "UAV" a small drone like ours,or was it a FULL-SIZE
aircraft that was remote controlled?

most likely it was a genie out of some Persian story, and dreamed up by
some
Russian journalist.

Assumptions like that get people killed.

Underestimating an enemy, or potential enemy, is a very dangerous thing to
do.

--
William Black

I've seen things you people wouldn't believe.
Barbeques on fire by the chalets past the castle headland
I watched the gift shops glitter in the darkness off the Newborough gate
All these moments will be lost in time, like icecream on the beach
Time for tea.

Paul J. Adam wrote:

Stealth aircraft aren't generally trying to play Kamikaze into warships
at sea.

True, but I have been thinking more in terms of getting no closer than
is required to identify the target and illuminate it with a laser. For
a ship near to the shore, you could that with a very small UAV, I
think: not easy to knock down, even if you're able to detect it.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk

Moritz Wünsch wrote:
schrieb:

The responses so far all point to several things:

snip
3. It is always likely to prove difficult to spot a small, stealthy UAV
by any means - visual, IR or radar. Furthermore, existing gun/missile
systems are not designed to engage such targets and may have great
difficulty in doing so.

What about using lidar?
In bad weather the drone/UAV might be degraded as well as your lidar-system.

And for defence/shooting them down maybe something like THEL could be
used, and I believe the range of THEL being superior to that of most gun
systems.

That sounds like a promising approach - but I believe it would be quite
a few years before such a system could be in service. Which is, of
course, the crux of the problem: the threat is relatively low-tech,
cheap, proven and available now, the responses to it are high-tech,
costly, unproven and available "sometime in the future".

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk

wrote:
Ken Chaddock wrote:


Block 1B CIWS has an infrared and optical tracker that would do nicely
against any UAV within it's range...the question is finding the UAV in
the first place. An Infrared search system with the ability to designate
to a B1B Phalanx would work quite well I think...


But a prop-driven UAV with a small engine and some attention to exhaust
masking would not be an easy IR target.

If all you want to do is locate and identify a ship, and beam an
illuminating laser at it to guide the incoming ordnance, then the UAV
can be very small and very hard to detect.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk

Have you ever seen the radar return from a prop ? Looks like a bloody
747...a prop-job wouldn't be a particular problem and contrary to
popular misconception, most modern IR trackers don't rely on a hugh heat
gradient but rather on the difference in emissivity between the target
and the background, IOW it's tracking the delta, not the absolute IR
output of the target...

....Ken

wrote:

:
:Fred J. McCall wrote:
: wrote:
:
: : Hint #3: A fighter with a 20mm Vulcan will flat mess up a "small,
: : slow UAV" and actually has a radar on board so that he can see it and
: : some actual training on how to do an air intercept, neither of which a
: : helicopter has.
: :
: :Always assuming that the radar is capable of getting a lock on the UAV.
:
: No such assumption is necessary. It's not like in the movies.
:
:What makes you so certain that gunnery radar WILL lock on to a stealthy
:UAV?

What makes you think that fighter aircraft use gunnery radar?

:The UAVs are designed, after all, to avoid being picked up by
:radar. For defence planning purposes the assumption has to be that
:radar will not probably work against them, unless and until it is
roved to be capable of doing so. To take any other attitude would be
:foolish complacency.

Which means nothing, since a fighter attacking with a gun uses
EYEBALLS to get the target and they're way up close.

: :If not, his chance of scoring a hit is remote - the speed differential
: :is so huge that he could do no more than 'spray and pray'.
:
: Hint #1: What do you think the landing speed of a jet fighter is?
:
: Hint #2: Guns work off the pilot's eyeballs.
:
:And exactly how will the pilot aim his guns, if the radar gunsight
:won't lock on and the sights he's got are no better than WW2 standards?

He'll aim them the same way he aims them against anything else. Times
have changed since WW2 and no 'radar gunsight' is required.

:Hint #1: in WW2 the Luftwaffe found that only between 2% and 5% of the
:shots they fired hit the target - and they were shooting at B-17s! Now
:scale down the target size to a UAV with a wingspan of a couple of
:metres, and work out how much ammo would have to be fired to nail one.

About 5 rounds.

:Hint #2: unlike the Luftwaffe's ammo, the current standard US 20mm
:aircraft SAPHEI shell, the PGU-28/B, does not have a tracer - so the
ilot will have no idea where his shots are going.

Nor does he need to. It's NICE to have radar, but it's hardly
necessary in order to score a lot of hits with a modern gun and HUD.

: :The basic problem is that naval self-defence systems are designed to
: :deal with large, fast objects which produce a nice big radar echo. We
: :know that they have problems picking up stealth planes - that's the
: :whole point of stealth planes, after all - so it is obvious that
: :they're going to have a hell of a lot more problems dealing with a very
: :much smaller and inherently stealthy object. I don't doubt they will
: :eventually find a means of coping with them, but that's probably years
: :away - and the threat exists now.
:
: Hint #4: The sky is NOT falling, Chicken Little....
:
:I sincerely hope that you have absolutely no connection with the
lanning of USN defence systems, because that sort of sneering
:complacency gets the wrong people killed.

I sincerely hope that you have absolute no connection with the
planning of ANY systems used by the military, because such abysmal
ignorance leads to unexecutable programs designed to counter
non-existent threats.

: :Note that according to the website above concerning the half-hour
: :terrorist flight over Israel "the Israeli army could also do nothing to
: :shut down the plane though they observed the entire flight over their
: :territory."
:
: And just why was that? It's a preposterous claim. If you can see it
: you can kill it.
:
:How, exactly? Ordinary MGs with eyeball sights stand hardly any chance
f connecting with a small plane at an unknown distance and travelling
:at an unknown speed, unless it comes very low and close. Radar FCS
:would probably not even pick it up.

And none of that applies to most modern aircraft, or even most modern
air defense weapons in general.

:The report I referenced has this to say: "According to a statement of
:Hezbollah leader, the flight over Israel to Nahariya lasted 14 minutes.
:Israeli side confirms this claim."
:
:The report also says: "Currently no country has an efficient defense
:against small low-flying UAVs, because existing air defense systems are
:not designed to counter threats of this type. Air defenses are mainly
:aimed at relatively large and fast planes. Thus, it is not surprising
:that Israeli air defense turned out to be weak against "Mirsad 1" UAV.
:Israeli army could also do nothing to shut down the plane though they
bserved the entire flight over their territory."
:
:Unless you have evidence that the report is a fabrication - in which
:case please post it here - what are your grounds for dismissing it,
:except of course that you don't want to believe it?

Because it's from an untrustworthy source and doesn't seem to fit the
facts of our current reality, however much it might accord with yours.

: :The situation is analogous to that posed by the first Russian anti-ship
: :missile, the Styx. It was around for years and no-one took much notice
: :until one sank an Israeli destroyer in 1967 -
:
: And was totally ineffective only 5 years later, although dozens were
: fired, with one even being downed by a 75mm gun.
:
:That's right: the Styx was a very big and quite slow missile which made
:a nice big target. Modern anti-ship missiles are in a completely
:different league. Please note that the Israelis now fit Phalanx to just
:about all of their warships.

So noted. So what? What does this have to do with the current
discussion?

: :then the USN woke up to
: :the need for a short-range defence system, and Phalanx was the eventual
: :answer.
:
: You have an interesting view of history is all I can say.
:
:So please explain - why in your opinion was Phalanx developed?

I was referring to your apparently belief that everyone was ignoring
everything up until 1967. This is merely a stupid belief, totally at
odds with the reality most of us live in.

:Just to help you, I have a copy of an article by the US technical naval
:historian Norman Friedman, which describes the Phalanx as "specifically
:designed to destroy incoming missiles which have survived other fleet
:defences."

Just to help you, we build the ****ing thing.

:Your basic attitude seems to be that the USN defences will work
erfectly as they do "in the movies", while their attackers will be
:easily defeated.

I don't feel particularly responsible for how things seem to you. I'd
attribute that to your meds, not anything to do with me.

:Try asking the crew of USS Stark about that. NO weapon
:system, offensive or defensive, can be relied upon to work all of the
:time, for a variety of technical and human failure reasons.

That's right, but again it's irrelevant to the current discussion.

--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn

"Paul J. Adam" wrote:

:In message , Fred J. McCall
writes
wrote:
::That's because ships haven't had to deal with UAVs before.
:
:Air targets are air targets. Helicopters are neither trained nor
:equipped to do air intercepts.
:
:Perhaps not in the USN, but there *are* other navies...

Really? Who? Of course the French come close, but other than them?
:-)

The only reason I can come up with to be training helicopters to do
air intercept work is a total lack of any ship much larger than a
destroyer. That's not a navy....

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney