Defense against UAV's

Mark Borgerson wrote:
In article ,
says...
wrote:
Andrew Swallow wrote:
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.
?? You transmit only when you want to issue new command to the swarm,
not to control every little thing. You can have minutes without
transmission, then 10ms transmission, followed by another long silence.

A machine can get a fairly accurate bearing in 10ms. Machines can be
made to be very patient so the several minutes is only a minor problem.
Several minutes allows wide angle receivers to be replaced by narrow
angle receivers sufficiently accurate to allow the targeting of weapons.


Narrow angle receivers require larger antennas or arrays of antennas.
Granted, that is easier at 900 Mhz than at 9Mhz.

Several minutes between hits on a narrowband frequency is different than
several hours---particularly if your platform is moving. Then you
get into problems with how accurately you know the position and
heading of the platform. Much more difficult than DF from a fixed
land base.

Mobile targets probably have to be attached by a plane that can chase them.

And you can also have plenty of cheap decoy trasmitters, just to make
it easier to intercept ... something. ;-)

Try brute force and ignorance - destroy the lot.
How many missiles will that take?

About 3 for every transmitter, depending on the accuracy of the DFing.
You will soon have a civilian population that is suspicious of decoy
transmitters.

Andrew Swallow

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

In which case they would use mines, ships are more easily sunk by
letting water in the bottom than by letting air in to the top. Mines
really are cheap and effective weapons.

Not necesarily. You have to lay mines.

Easily done by anything from a traditional dhow to a helicopter

The US could blow the ship out
of the water.

They'd have to know you were laying mines. The straits of Hormuz are passed
by dozens of Iranian vessels every day (and night). Covert mine laying
is old hat.


UAVs are mobile. You can launch them from deep inside
Iran. Also mines being static can be swept.

Not a simple task, especially if the minesweepers are subject to attack

A mobile mine (a USB) would
be quite a threat.


Floating mines have existed for many decades


Note that the Iranians are as dependent on free traffic movement through
the straits as everyone else.

True, but

1) They might be prepared to hurt themselves to hurt us. In a full
scale war they wont care.


I suspect they will when they run out of money and food

2) They will time the passage and routes of their own vessels so that
they don't get attacked.


And you dont think the USN would interict their ships huh ?


If deterrence really did work defense policy would be a lot simpler.


Keith



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I think we have some hisory here. During Iran - Iraq Iran did indeed
lay some mines. The US was in a much more difficult position legally
from what would be the case were the US to be a belligenent. "Blow it
out of the water" assumed US belligerent status. The US while "neural"
did sink some minelayers and very nearly became a belligerent on Iraq's
side.

Te USN would be a lot more aggressive with a defined legal position.
The US sank ships but did not mount strikes on Iranian naval facilities.

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.

wrote in message
ups.com...



I think we have some hisory here. During Iran - Iraq Iran did indeed
lay some mines. The US was in a much more difficult position legally
from what would be the case were the US to be a belligenent. "Blow it
out of the water" assumed US belligerent status. The US while "neural"
did sink some minelayers and very nearly became a belligerent on Iraq's
side.

Te USN would be a lot more aggressive with a defined legal position.
The US sank ships but did not mount strikes on Iranian naval facilities.



Covertly laying mines is less likely to attract strikes than overt
attack using drones.

Keith



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In article ,
says...

wrote in message
ups.com...

In which case they would use mines, ships are more easily sunk by
letting water in the bottom than by letting air in to the top. Mines
really are cheap and effective weapons.

Not necesarily. You have to lay mines.

Easily done by anything from a traditional dhow to a helicopter

The US could blow the ship out
of the water.

They'd have to know you were laying mines. The straits of Hormuz are passed
by dozens of Iranian vessels every day (and night). Covert mine laying
is old hat.


UAVs are mobile. You can launch them from deep inside
Iran. Also mines being static can be swept.

Not a simple task, especially if the minesweepers are subject to attack

A mobile mine (a USB) would
be quite a threat.


Floating mines have existed for many decades


Note that the Iranians are as dependent on free traffic movement through
the straits as everyone else.

True, but

1) They might be prepared to hurt themselves to hurt us. In a full
scale war they wont care.


I suspect they will when they run out of money and food

I wouldn't hold my breath if I were you. High oil prices have
allowed Iran to build up about $40Billion in foreign capital
reserves. As for the hunger factor--according to the FAO,
Iran is a net exporter of food.

http://www.fao.org/countryprofiles/i...so3=IRN&subj=4

2) They will time the passage and routes of their own vessels so that
they don't get attacked.


And you dont think the USN would interict their ships huh ?


Probably---but would they stop Japanese and Chinese ships loaded
with Iranian oil that has already been purchased?

If deterrence really did work defense policy would be a lot simpler.


Keith


Mark Borgerson

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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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.

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


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.

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.

Andrew Swallow

In article .com,
says...

wrote:
This implies 1000 km of constant wind and cloud.

Not necessarily. They could be further apart in good weather and closer
toghether in bad. As far as wind is concerned COTS provides cheap (1m
or less) GPS. They could stay in formation unless the wind speed
exceeded forward speed. Unlikely.

Wind is never homogenous and never from the same direction, especially
over 1000klicks, all the 100 or 500 or whatever comms checks on
position would certainly excite someone on the Elint watch. Those
people are good, by the way, and have a real ear for the rare and
unusual.

Do you have a range (distance) for communications in this manner by the
way?


The $179, spread-spectrum, 1W, 900Mhz radios we use for telemetry
have line-of sight ranges up to 40 miles.

You can check out the state of the art in commercial products at

http://www.maxstream.net/products/


That would be fine for covering the Straits of Hormuz. For that
you don't need a 1000km swarm in any case.

Mark Borgerson

In article ,
says...
wrote:

:Not necessarily. They could be further apart in good weather and closer
:toghether in bad. As far as wind is concerned COTS provides cheap (1m
r less) GPS.

Hint: Look up the accuracy specifications of GPS.


Hint #2; consider that the improvements due to WAAS are not
available outside North America.

Hit #3: Consider the difference between accuracy and relative
precision. The accuracy needed to transmit a target location
is different from the relative precision you need to keep
from colliding with other UAVs in the swarm.


Mark Borgerson

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. 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.

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.

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.

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.

To do peer-peer communication is something which has been considered, a
lot of development would be needed.

What I think is amazing is the pace of COTS development. It provides a
very good arument against secret projects. What in fact I had in mind
was the provisions of contracts to the perveyors of COTS to advance
their act in military directions. The military could make the new
generation of Internet appear faster. The experts talk about

1) Specificicity. This will involve linguistic research. If you put in
"lock" it will know whether you mean "eclusia" or "cerradura".

2) This is relevant here. The ability of a mobile phone to read a
nearby screen. This is the whole concept of connectivity.

Why not provide funds to get this done? No secrecy required. Tell Al
Qaeda about the strength and breaking strain of the rope.