The nail in the coffin: TIS and Mode-S

Paul Tomblin writes:

Wanna bet?
http://gps.faa.gov/FAQ/index.htm
"These correction messages are then broadcast through communication
satellites to receivers onboard aircraft using the same frequency as GPS."

The communication satellites mentioned are not GPS satellites.

But that's just the FAA, what do they know. Obviously you got better
information from your flight simulator manual.

No, I got my information from the original GPS specifications, years ago,
along with some later reading to try to keep up on trends. That's one reason
why I'm able to distinguish between communication satellites and navigation
satellites when I read about them, which helps prevent me from saying foolish
things in open discussions.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Roger writes:

The only thing I found was slightly different. "These corrections
messages are then broadcast to receivers onboard the aircraft using
the frequency as the GPS". It said nothing about being broadcast
through communications satellites, or I missed it.

As I recall, the WAAS correction data are broadcast over large areas by
relaying them through communication satellites. However, these communication
satellites are not part of the GPS system, and they are not GPS satellites.

IF correction messages can be sent from local areas back to satellites
that would make they very vulnerable to tampering with the data.

Yes. But the satellites in question are not part of GPS, fortunately.

It _is_ a bit unfortunate that WAAS is using the same frequencies to create
pseudosatellites, which is essentially spoofing GPS, and it's not a good idea
to have spoofing technology in such widespread use, no matter what the
justification.

--
Transpose mxsmanic and gmail to reach me by e-mail.

In a previous article, Mxsmanic said:
Paul Tomblin writes:
Wanna bet?
http://gps.faa.gov/FAQ/index.htm
"These correction messages are then broadcast through communication
satellites to receivers onboard aircraft using the same frequency as GPS."

The communication satellites mentioned are not GPS satellites.

Your statement, I quote was "They do contribute to WAAS, but there are no
satellites in that." There *are* satellites in that, so you are wrong.
100% wrong. Admit it and stop weaseling.


--
Paul Tomblin http://blog.xcski.com/
Today is a good day. Not because anything wonderful is happening, so
much, but because my definition of a 'bad day' has been revised.
-- Chris Klein

In a previous article, Roger said:
On Tue, 27 Mar 2007 18:43:48 +0000 (UTC),
(Paul Tomblin) wrote:
"These correction messages are then broadcast through communication
satellites to receivers onboard aircraft using the same frequency as GPS."

The only thing I found was slightly different. "These corrections
messages are then broadcast to receivers onboard the aircraft using
the frequency as the GPS". It said nothing about being broadcast
through communications satellites, or I missed it.

If you were using WAAS, you should get to know the WAAS satellite coverage
areas. I think they fixed the problem, but for a while there the coverage
was **** poor is in New Hampshire and Maine.

IF correction messages can be sent from local areas back to satellites
that would make they very vulnerable to tampering with the data.

At one time the FAA was talking about using ground based broadcast
stations, called LAAS (Local Area Augmentation System). (Which, by the
way, used different frequencies than the GPS constellation.) As far as I
know, none have been deployed yet or they dropped the idea.

--
Paul Tomblin http://blog.xcski.com/
"Of the many tragedies of Vietnam, this raw class discrimination strikes
me as the most damaging to the ideal that all Americans are created equal
and owe equal allegiance to their country." - Colin Powell (pre-sell out)

"Paul Tomblin" wrote in message ...

At one time the FAA was talking about using ground based broadcast
stations, called LAAS (Local Area Augmentation System). (Which, by the
way, used different frequencies than the GPS constellation.) As far as I
know, none have been deployed yet or they dropped the idea.


That reminds me -- I miss hearing from John "WAAS-is-dead" Tarver.
He was almost as amusing as the manic simmers.
Maybe we ignored John too much and he went away.
Our loss, I guess. :-/

Paul Tomblin wrote:
If you were using WAAS, you should get to know the WAAS satellite coverage
areas. I think they fixed the problem, but for a while there the coverage
was **** poor is in New Hampshire and Maine.

I don't know if I'd call it "**** poor", but much of Maine and
ocasionally the rest of New England lose LPV coverage often.
Southern California often loses out, too. Here's a real-time
coverage map:

http://www.nstb.tc.faa.gov/vpl.html

On Mar 27, 9:33 pm, (Paul Tomblin) wrote:
In a previous article, Mxsmanic said:

Paul Tomblin writes:
Wanna bet?
http://gps.faa.gov/FAQ/index.htm
"These correction messages are then broadcast through communication
satellites to receivers onboard aircraft using the same frequency as GPS."

The communication satellites mentioned are not GPS satellites.

Your statement, I quote was "They do contribute to WAAS, but there are no
satellites in that." There *are* satellites in that, so you are wrong.
100% wrong. Admit it and stop weaseling.

Not to mention "contribute to WAAS" being off the mark.

It's worth pointing out that the GEOs also being used to provide a
separate ranging source (bent pipe) in addition to the information
being supplied (corrections, integrity, etc.) in the WAAS messages.

--
Paul Tomblin http://blog.xcski.com/
Today is a good day. Not because anything wonderful is happening, so
much, but because my definition of a 'bad day' has been revised.
-- Chris Klein

Regards,
Jon

John R. Copeland wrote:
"C J Campbell" wrote in message news:2007032711300622503-christophercampbell@hotmailcom...
On 2007-03-26 23:13:16 -0700, scott moore said:

Let's say, just say, that the FAA disappeared. WAAS would die, right?
Are you sure that the FAA funds GPS satellites?


He said WAAS.


Excellent. Someone who reads.

Scott

In article ,
(Paul Tomblin) wrote:

At one time the FAA was talking about using ground based broadcast
stations, called LAAS (Local Area Augmentation System). (Which, by the
way, used different frequencies than the GPS constellation.) As far as I
know, none have been deployed yet or they dropped the idea.

I think there were two deployed. The manufacturer was a Canadian company
that was bought out by Honeywell.

At one time the FAA was talking about using ground based broadcast
stations, called LAAS (Local Area Augmentation System). (Which, by the
way, used different frequencies than the GPS constellation.) As far as I
know, none have been deployed yet or they dropped the idea.

I think there were two deployed. The manufacturer was a Canadian company
that was bought out by Honeywell.

http://gps.faa.gov/programs/laas/currentnews-text.htm