On Jun 25, 7:34*am, Mike Jr wrote:
On Jun 25, 6:14*am, "Tim Springer"
wrote:

Read the article I wrote on the SVN 49 issue. It is out on the Inside GNSS
"frontpage" (http://insidegnss.com) now and will be included in the
July/August printed version

The article nicely shows and explains what is being done and why that works
(for "ordinary" users).

For the direct link to the article visit my blog at:http://gnss.servolux.nl/gnss_blog.html

Tim

"The tweaking of the satellite broadcast ephemerides and time is
designed to reduce the pseudorange error to within the specifications
for GPS Standard Positioning Service and Precise Positioning Service."

That ain't no .75 meters!

More later when I have time.

--Mike Jr

Tim,
The specification for the GPS Standard Positioning Service is 100
meters.

Some very smart and hardworking people have managed to get the
Unexplained Range Error down to .75 meters. It is this level of
service that people have come to expect and rely on from GPS. Now the
wing wants to throw this brick, the "worst performing block IIA in the
constellation", at the users and try to hide behind a 100 meter
requirement that was long ago left in the dust bins.

The wing is looking for political cover. Lets examine just some of
the consequences.
1. DOT wants to use GPS for real time tracking of railroad train
positions. Just imagine a future crash because someone thought the on
coming train was on the other track.

2. DOT needs to land airplanes.

3. The end users, DOT/DoD/Intel/RTK are going to have to adjust their
equipment to ignore this bad bird. What is that going to cost?

3. The wing's perceived incompetence in managing the GPS constellation
is only stoking the fires for Galileo. Galileo is on the ropes
because their business model doesn't make sense ("We are going to
charge you for precise positioning. What? GPS gives you .75 meter URE
for free. Curse those Americans!") But now they can point to the
wing's handling of SVN049 and say, "See. You need us".

4. The Obama administration would love to take GPS away from the
military and give it to DOT. "Under DOT we can play nice with the
Europeans!". This would be a disaster for the DoD/Intel community who
need a military GPS.

I don't think the wing has thought this through.

Man, that block IIF sure better shine when it gets launched. BTW, how
can Boeing launch eight IIF satellites in 2010 when it takes about six
months to bring the first in a new block online?

These are interesting times.

--Mike Jr