Galileo : US - EC negotiations outputs.

(Henry Spencer) wrote in
:

In article ,
Sander Vesik wrote:
...But in reality, GPS jamming does not appear
to be overly effective - even when used on "home turf"...

In 1992, in tests run by Britain's Defence Research Agency, a jammer
radiating 1W of noise in the GPS band incapacitated civilian GPS
receivers at a distance of 22km. Worse, at somewhat longer distances
the receivers still claimed to be working but in fact lost accuracy
rather badly.


Of course, since it can jam at 22km, it will be detectable by anti-
radiation missle seekers at an even longer range... (be surprising if HARM
didn't work at this frequency).

--
Reed

(Henry Spencer) wrote in
:


Ah, but the situation is not symmetrical. The US would not be
trusting "the Europeans"; it would be trusting an international
consortium which would include the US (and already includes major
non-European countries).


Much like the UN, in other words...

So long as the "single-nation veto rule" isn't in effect, this might not be
entirely awful.

--
Reed

John Schilling wrote:
snip
But that puts it squarely in the technical arena. To what extent does
Galileo use spread-spectrum techniques that make it resistant to jamming?
To what extent can Galileo's operators selectively deny precise targeting
data in one theater without shutting down the whole system globally?

GPS (in the generic sense) has big problems with power budgets.
The GPS signal from each satellite is on the order of 50W.
Over a simple jammer, the spreading code for GPS provides a gain
of 1000, or 10000 for the military version.

Now, divide 50Kw, or 500Kw by the area of a hemisphere of earth, and
work out the power per square meter.
It's not a really large number.
Jamming this is EASY.
You can overcome jamming somewhat by pointing antennas at where you
expect the satellites to be, but this gets complex rapidly.

However, for some sorts of military assets, this is not a problem.

If you have a inertial navigation system then an important use for
GPS is not to tell you where you are, but to null out the errors that
accumulate while you are flying towards the target.
In some cases, if the GPS signal goes away 250Km away from the target
this will be almost as good, as you have relatively little time for
the errors to build up if you'r flying in at near sonic velocity.

(Henry Spencer) wrote in message ...
See above. But yes, it is largely a duplication. The US could save a lot
of time, money, and effort if it joined the Galileo consortium and closed
down GPS. Vice-versa doesn't work, because there is no GPS consortium and
no way to join it.

Sure, the US could save lots of money by shutting down GPS and joining
Galileo. But the Europeans could save lots of money by not building
Galileo in the first place and just continuing to use GPS. The
arguments for and against are largely the same - something that you
and you alone control is preferable to something that someone else
controls, with something that a consortium you are a part of controls
being somewhere in the middle.

And I think that people expecting Galileo to stay functional in the
event of serious armed conflict involving the US are setting
themselves up for a rather unpleasant surprise. Maybe it will be
because the Europeans don't like the other party to the conflict,
maybe it will be because the US leaned on them heavily, and maybe it
will be because American spooks compromised some segment of the
Galileo control system, but the smart money is on it going down.

-jake

"Dr. O" dr.o@xxxxx writes:

Exactly my thoughts. The potential political outfall of Galileo being used
by adversaries of the U.S. in an armed conflict will only result in the
Euros themselves pulling the plug on Galileo instead of someone else (the
U.S.) doing it for them. Now what use is it to spend billions of dollars
just to be able to say 'I want to pull the plug, I don't want anyone else to
do it for me'?

No.

But it might be something along the lines of "I don't want to depend on
US military good will in future. I did so for long enough. The risk of
US pulling a plug on us for not further specified reasons of 'Homeland
Security (tm)' is getting larger and larger these days. Today it's enough
to be a world famous 70+ years old musician happening to live in Cuba,
and you don't get a permission to enter the US. Tomorrow, it might
suffice to allow people to run anything but MS operating systems, or to
use PGP for private communication, to get cut off of the GPS service."

Try to imagine a situation where the control of the only satellite
navigation system is in hands of the EU. Even better: Russia. How long
do you think would it take the US to build and launch own system? Would
you also oppose it, even if it was a mere duplication of the existing
system?

That seems ludicrous to me. I've been argueing this for a
long time but, as always, no one is listening to me.

What, and you never stopped to think of where that comes from? :-)

In short, it means the Galileo system cannot be relied upon for autonomous
navigation (in airplanes or cars)

Care to explain how you came to this conclusion?

and is therefore all but useless.

Sure.


Cheers, alex.

Reed Snellenberger wrote:
(Henry Spencer) wrote in
:

In article ,
Sander Vesik wrote:
...But in reality, GPS jamming does not appear
to be overly effective - even when used on "home turf"...

In 1992, in tests run by Britain's Defence Research Agency, a jammer
radiating 1W of noise in the GPS band incapacitated civilian GPS
receivers at a distance of 22km. Worse, at somewhat longer distances
the receivers still claimed to be working but in fact lost accuracy
rather badly.


Of course, since it can jam at 22km, it will be detectable by anti-
radiation missle seekers at an even longer range... (be surprising if HARM
didn't work at this frequency).


A mobile phone was a peak power output of over 1.5W. Considering we are talking
about something simpler and equally mass-producable, putting one such with a
rechargable battery and PVC every 5sq.km (and more densly in urban centers etc)
would not really be a major expenditure of money yet be extremely annoying
and expensive to remove with HARMs.

--
Sander

+++ Out of cheese error +++

Jake McGuire wrote:
(Henry Spencer) wrote in message ...
See above. But yes, it is largely a duplication. The US could save a lot
of time, money, and effort if it joined the Galileo consortium and closed
down GPS. Vice-versa doesn't work, because there is no GPS consortium and
no way to join it.

Sure, the US could save lots of money by shutting down GPS and joining
Galileo. But the Europeans could save lots of money by not building
Galileo in the first place and just continuing to use GPS. The
arguments for and against are largely the same - something that you
and you alone control is preferable to something that someone else
controls, with something that a consortium you are a part of controls
being somewhere in the middle.

It is not "just" a question of control - control is merely one part of it,
and GPS would need a lot of redesign to meet those. Which is unlikely
to happen, and similarily, a system that would use GPS for navigation and
use add-on satellites for the rest is unlikely as it would broadly cost
the same as Galileo and still have all the drawbacks of GPS.


And I think that people expecting Galileo to stay functional in the
event of serious armed conflict involving the US are setting
themselves up for a rather unpleasant surprise. Maybe it will be
because the Europeans don't like the other party to the conflict,
maybe it will be because the US leaned on them heavily, and maybe it
will be because American spooks compromised some segment of the
Galileo control system, but the smart money is on it going down.

Galileo is not really a EU navigation system, its a EU + ESA + Russia +
China + India navigation system.


-jake

--
Sander

+++ Out of cheese error +++

In article ,
Reed Snellenberger wrote:
In 1992, in tests run by Britain's Defence Research Agency, a jammer
radiating 1W of noise in the GPS band incapacitated civilian GPS
receivers at a distance of 22km...

Of course, since it can jam at 22km, it will be detectable by anti-
radiation missle seekers at an even longer range...

Not necessarily. GPS signals are *really* faint; it takes advanced signal
processing (which they are specifically designed to permit) to pull them
out of the background noise at all. I wouldn't be surprised if you could
raise the noise level enough to make them unusable without radiating enough
power for a distant seeker to lock onto reliably.

And as others have noted, one-watt noise jammers will not be large or
costly, and could easily be sprinkled around generously.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Reed Snellenberger wrote in message 3.121...
(Henry Spencer) wrote in
:

In article ,
Sander Vesik wrote:
...But in reality, GPS jamming does not appear
to be overly effective - even when used on "home turf"...

In 1992, in tests run by Britain's Defence Research Agency, a jammer
radiating 1W of noise in the GPS band incapacitated civilian GPS
receivers at a distance of 22km. Worse, at somewhat longer distances
the receivers still claimed to be working but in fact lost accuracy
rather badly.


Of course, since it can jam at 22km, it will be detectable by anti-
radiation missle seekers at an even longer range... (be surprising if HARM
didn't work at this frequency).
Hmm. How many 1W jammers can you make? How much would they cost? How
many HARMs are there? How much do they cost?

Of course, military receivers are more difficult to jam for several
reasons, including directionality. But then again how much does it
cost to launch hundreds of weather balloons, each carrying a few W
jammer?

Stefan

In article ,
Peter Fairbrother wrote:
Meaconing jammers, if I may call them that, would cost more and require a
receiver as well as a transmitter. Say $20 each.

I think they would be significantly harder to build, if you want them to
meacon the encrypted precision code and not just the coarse acquisition
code. (Warning, slight oversimplifications follow...)

Ordinary GPS receivers essentially use statistical techniques which rely
on knowing the digital pattern used; that way, they can pick out signals
which are lost in the background noise by any normal standard. But if you
want to meacon an encrypted signal (whose pattern you don't know), you
can't do that. I'd guess you'd have to use a steered directional antenna
to receive a clean signal from one particular satellite without any
advance knowledge of the signal. That's certainly feasible, but it does
make a GPS meaconing system a rather larger and more expensive piece of
hardware.

Mind you, just meaconing the coarse code (which is public knowledge) of a
few of the satellites will still make things difficult. Civilian and
cheap military receivers use only the coarse code, and even the fancier
military ones which use the precision code mostly need the coarse code to
help them get synchronized with the satellites.

One extra advantage of war-time meaconing was that you could lure the enemy
into your killing zone, rather than just sending him astray.

That's harder than just messing things up at random, but it's not
unthinkable.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |