Galileo : US - EC negotiations outputs.

Derek Lyons wrote:

(Henry Spencer) wrote:

And as others have noted, one-watt noise jammers will not be large or
costly, and could easily be sprinkled around generously.

Only so long as you don't have to account for the power source.

D.

D. Hmmm.

A "D" primary alkaline cell of the "lasts longer" brand will give around
21,000 mAh over 24 hours. Probably more now, that figure's a few years old.
Well enough to power a 1W jammer for a day.

They are ridiculously expensive though. £3.52 for two! A scandal! Buy the
cheaper ones instead. 19,000 mAh or so is still enough for a day.

How long will the war last?
--
Peter Fairbrother

Henry Spencer wrote:

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,

That's a cost for a re-transmitter on a balloon. The signal to be
re-transmitted would come from a complex system involving dishes and lots of
computers working out where the retransmitters were and what an enemy
incoming would see if it was in the desired wrong place. Or something like
that, I haven't gotten it clear in my mind yet.

I was thinking about directed repositioning, rather than just messing things
up. Lots of retransmitters spread around the sky on balloons, and a computer
system, so the enemy would see the signal coming from the right direction.
Localised as well, with each target in a different meaconing space, so you
can divert many targets at the same time, perhaps to different destinations.
And get the missiles to land back on the people who fired them.


One thing that has often puzzled me is why the simpler types of radar,
especially antiair radar, where the beam is not finely steered, do not
separate the transmitter from the receiver and associated circuitry. You
have three or four transmitters and put them 200m from the truck with the
expensive electronics, only using one at a time. You keep the genny in the
truck too.

After the HARM comes in, you just switch another transmitter on. No harm
done. Transmitters like that, just a power amp and an antenna, maybe some
coarse steering servo's, should be a darn sight cheaper than HARM's.

(Henry Spencer) wrote


(Generating coherent radiation is easy at microwave frequencies -- most
microwave transmitters are coherent -- but generating a really tight beam
is inherently hard regardless of the exact type of transmitter. Microwave
wavelengths are 4-5 orders of magnitude longer than that of light, and the
beam's inherent tendency to spread due to diffraction is larger by the
same factor... so you need *optics* that are larger by the same factor to
generate an equally tight beam.)

Late in their run, our friends the Soviets were considering a sparse
coherent array of microwave transmitters (several biggish dishes
distributed over a field a few kilometers in extent with some sort
of phasing scheme) for an ASAT weapon. I don't think they got very far,
and don't remember what the targets were if I ever knew.

The Sovs were, however, generally interested in taking out GPS -- it
was one of the proposed targets for the SS-19-based ASAT that
subsequently evolved into ROKOT/BRIZ.

"Sander Vesik" wrote in message
...
Dr. O dr.o@xxxxx wrote:

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

Yeah right.


In short, it means the Galileo system cannot be relied upon for
autonomous
navigation (in airplanes or cars) and is therefore all but useless.


In short it means you have no clue on the issues.


I will be proven right. As always.

"Alex Pozgaj" wrote in message
...
"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."

That's a ludicrous accusation with no prior record to back it up.


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?

The GPS system was originally devised for military purposes and that is
still it's 'official' role. Any nation who devises a similar system (apart
from the EU) would probably do so for military reasons foremost and it
wouldn't surprise me if the U.S. had duplicated Glonass if the Soviets beat
them to it (actually, the Soviets duplicated GPS with Glonass).

However, since the EU and US aren't military adversaries and the proclaimed
primary usage for the Galileo system will be commercial, non-military
applications I cannot see any viable reason for duplicating the US system,
ESPECIALLY if there isn't a guarantee that the system availabillity will be
greater than the US system. Ditto for the accuracy.

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

"Alex Pozgaj" wrote in message

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."

That's a ludicrous accusation with no prior record to back it up.

It was a bit of a stretch, or course, to make my point clearer.

On the other hand, it was actually not *that* ludicrous, if you take
a look at the current developments in the US. As already mentioned,
refusing the bunch of world-famous (Buena Vista Social Club) granpas
the permission to enter US *on a business trip* for reasons of
national security is almost as unbelievable as what I suggested
above.


Cheers, alex.

In article ,
Peter Fairbrother wrote:
One thing that has often puzzled me is why the simpler types of radar,
especially antiair radar, where the beam is not finely steered, do not
separate the transmitter from the receiver and associated circuitry. You
have three or four transmitters and put them 200m from the truck with the
expensive electronics...

Interesting question.

One reason that immediately comes to mind is that there is a problem with
where to point the receiving antenna: only from the immediate vicinity of
the transmitter are the things currently illuminated by the beam all in
the same direction. Seen from a receiver 200m from the transmitter, a
target 1km away and a target 2km away, lined up so they are in the beam
simultaneously, are 5-6deg apart.

The military has long been *interested* in "bistatic" radar, with
transmitter and receiver well separated, but the technical problems are
serious and it's not yet in wide use. (There have been some interesting
experiments, mind you, with tracking aircraft using things like commercial
TV transmitters as the signal source -- that way, the tracking system
itself doesn't emit at all.)
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

In article ,
Derek Lyons wrote:
And as others have noted, one-watt noise jammers will not be large or
costly, and could easily be sprinkled around generously.

Only so long as you don't have to account for the power source.

Depends on whether you want them to last for a day or two, or months. As
others have noted, for short-term operation, batteries are neither costly
nor heavy.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |