In message , Tim
writes
On Thu, 23 Sep 2004 15:57:55 +0000, Peter Masson wrote:

(Can GPS identify which line the train is on if adjoining
platforms are different lengths?)

Not with any certainty.

Of course, what happens if the Pentagon decided to turn off GPS for
civilian use without warning (which they've always stated they have the
right to do)?

Or worse, they have a war and introduce deliberate errors into the system
designed to confuse the enemy?

I can see it now on the 9:24 from Tonbridge: "We will shortly be arriving
at Copenhagen, please mind the step"

I know that Europe is going to deploy it's own GPS sats, but I don't know
when that will be.

Timbo

The European system is already being deployed, the first satellite is
already up (of course you need at least 4 for a good position),
forgotten the name of the system though..
The Russians have their own system called GLASNOSS and the Chinese have
also started sending up satellites so they have their own version as
well.
--
Regards,

James Christie

"In the beginning the Universe was created. This has made a lot of people very
angry and been widely regarded as a bad move."
- Douglas Adams

"James Christie" wrote in message
...



With difficulty, because GPS has an accuracy of +/- 100m, unless of course
you are using Differential GPS, but that is mainly a maritime system.
--

It's been somewhat better than that for a while, since the "random error"
was removed. IME the error is probably nearer 2 metres. Though the powers
that be can reintroduce the random factor, or turn it off entirely, should
they feel the need.

G

In message , at 15:24:24 on Thu,
23 Sep 2004, John Rowland
remarked:
The obvious solution seems to be individual doors which check that there is
a platform adjacent before opening.

No doubt they would also say "glad to be of service" when they open.
--
Roland Perry

In article ,
Tim wrote:
On Thu, 23 Sep 2004 15:57:55 +0000, Peter Masson wrote:

(Can GPS identify which line the train is on if adjoining
platforms are different lengths?)

Not with any certainty.

Of course, what happens if the Pentagon decided to turn off GPS for
civilian use without warning (which they've always stated they have the
right to do)?

Galileo. And, indeed, Glonass (which we have now - and most receivers are
dual GPS/Glonass)

Or worse, they have a war and introduce deliberate errors into the system
designed to confuse the enemy?

Galileo. And, indeed, Glonass.

I can see it now on the 9:24 from Tonbridge: "We will shortly be arriving
at Copenhagen, please mind the step"

Galileo. And, indeed, Glonass.

I know that Europe is going to deploy it's own GPS sats, but I don't know
when that will be.

Galileo, not GPS. A much better system (it'll have to be if it's to do a
fraction of what they're wanting it to do). The programme is being pushed
ahead hard and should be delivering in the next 3-5 years (depends how
fast the constellation goes up, which in turn depends on who'll be
launching). In the meantime there's Glonass, which the Pentagon certainly
doesn't have a veto over.

--
Andy Breen ~ Interplanetary Scintillation Research Group
http://users.aber.ac.uk/azb/
"Time has stopped, says the Black Lion clock
and eternity has begun" (Dylan Thomas)

In article ,
ANDREW ROBERT BREEN wrote:

/GPS-replacement/

Galileo, not GPS. A much better system (it'll have to be if it's to do a
fraction of what they're wanting it to do). The programme is being pushed
ahead hard and should be delivering in the next 3-5 years (depends how

Should have added - first satellite is up, more coming. Not checked in the
last few months on the launch schedule for the rest of it, and the best
accuracy will depend on other stuff in the pipeline - but that's for
things like landing airliners under Galileo control..

--
Andy Breen ~ Interplanetary Scintillation Research Group
http://users.aber.ac.uk/azb/
"Who dies with the most toys wins" (Gary Barnes)

In message , James Christie
writes
In message , Tim
writes
On Thu, 23 Sep 2004 15:57:55 +0000, Peter Masson wrote:

(Can GPS identify which line the train is on if adjoining
platforms are different lengths?)

Not with any certainty.

Of course, what happens if the Pentagon decided to turn off GPS for
civilian use without warning (which they've always stated they have the
right to do)?

Or worse, they have a war and introduce deliberate errors into the system
designed to confuse the enemy?

I can see it now on the 9:24 from Tonbridge: "We will shortly be arriving
at Copenhagen, please mind the step"

I know that Europe is going to deploy it's own GPS sats, but I don't know
when that will be.

Timbo

The European system is already being deployed, the first satellite is
already up (of course you need at least 4 for a good position),
forgotten the name of the system though..
The Russians have their own system called GLASNOSS and the Chinese have
also started sending up satellites so they have their own version as
well.

********, its GLONASS, I ALWAYS get that the wrong way round......
--
Regards,

James Christie

"In the beginning the Universe was created. This has made a lot of people very
angry and been widely regarded as a bad move."
- Douglas Adams

John Rowland wrote:
"Peter Masson" wrote in message
...
"John Rowland" wrote in
message ...

The obvious solution seems to be individual doors which
check that there is a platform adjacent before opening.

Something along the lines of a transponder at the start
of each platform which is detected by each door and
enables the doors on the appropriate side, and another
one at the end of each platform which disables each door.
Some complications for platforms on reversible lines

Ware springs to mind, and most termini. That sounds high-tech enough
to break down a lot, and requires fitting of kit at stations, which
are the most easily vandalised part of the railway. I was thinking of
a projecting metal arm under each train door which prods the platform.

Is it too easy to simply extend the platform?

John Rowland wrote:

"Peter Masson" wrote in message
...
"John Rowland" wrote in message
...

The obvious solution seems to be individual doors which
check that there is a platform adjacent before opening.

Something along the lines of a transponder at the start
of each platform which is detected by each door and
enables the doors on the appropriate side, and another
one at the end of each platform which disables each door.
Some complications for platforms on reversible lines

Ware springs to mind, and most termini. That sounds high-tech enough to
break down a lot, and requires fitting of kit at stations, which are the
most easily vandalised part of the railway. I was thinking of a projecting
metal arm under each train door which prods the platform.

Considering the range of actual platform dimensions, that is
quite a large prod. Plus all the gear to ensure it is proved
retracted and locked whilst the train is moving.....

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.

--- "Roland Perry" wrote:

John Rowland
remarked:
The obvious solution seems to be individual doors which check that there
is
a platform adjacent before opening.

No doubt they would also say "glad to be of service" when they open.

And the buffet serves something that's almost, but not quite, entirely
unlike tea. (Oh, wait. That already happens...)

Chris J Dixon wrote:

Ware springs to mind, and most termini. That sounds high-tech
enough to break down a lot, and requires fitting of kit at
stations, which are the most easily vandalised part of the
railway. I was thinking of a projecting metal arm under each
train door which prods the platform.

Considering the range of actual platform dimensions, that is
quite a large prod. Plus all the gear to ensure it is proved
retracted and locked whilst the train is moving.....

Or one of those detector thingies they have on the back of BMWs to
detect an obstruction whilst you're backing..

No moving parts.

--
Chris Game

"Hopefully the net-dwelling paranoid delusional conspiracy theorists
won't descend upon me " -- Chris Pratley, MSFT.