Re: Garmin and the D

Happy Trails <nomail@xxxxxxxxxxx> wrote:

Besides carrying a time stamp indicating the epoch to which it first
applies, and the satellite it applies to, each differential correction
carries a range correction for the satellite, in meters, usually
something in the neighbourhood of +/- a fraction up to several dozen,
or even hundreds of meters, and a "range rate of change" correction,
telling +/- the amount by which it is expected to change per second
over the next few seconds in case there is not a new correction
available immediately for any given satellite.

are you sure it is just that? for example: here at W23,S46 we are far
away from any WAAS ground station, but if I turn WAAS on I do get the
corrections (and the "D" to prove it!);

how is my receiver supposed to know that it should *not* use those
corrections because they were taken by a ground station too far away;
(I'm assuming corrections could be due to *local* causes like the shape
of the ionosphere);

You may not have a "D" showing for any given sat for the reason you
mentioned, or because it's signal has just been interrupted
temporarily as you pass under a tree, or it is below a preset mask
angle, or either you or the base has not yet been tracking that sat
long enough to have determined that a clean, filtered signal suitable
for DGPS is available, or . . . .

should'nt *all* "D"s disapear at once when you lose your connection to
the geostationary WAAS sat ?

[]s,

--
Otavio Exel /<\oo/>\ oexel@xxxxxxxxxxxxxxxxxx
.

Relevant Pages

  • Re: Light Clock Nonsense
    ... Paul. ... >> If it is so easy to turn off the correction it must also be easy to alter it. ... > of the very first satellite. ... clocks behave in microgravity so perhaps Paul ...
    (sci.physics.relativity)
  • Re: GPS versus source dependency / ballistic theory
    ... Are you FINALLY willing to admit that the GR correction of deltaF/F = ... are due to inherent limits of the atomic clocks, ... insertion, irregularities in the Earth's gravitational field, etc. amount ... per day are cumulatively recorded and broadcast along with the satellite ...
    (sci.physics)
  • Re: GPS versus source dependency / ballistic theory
    ... Are you FINALLY willing to admit that the GR correction of deltaF/F = ... are due to inherent limits of the atomic clocks, ... insertion, irregularities in the Earth's gravitational field, etc. amount ... per day are cumulatively recorded and broadcast along with the satellite ...
    (sci.physics.relativity)
  • Re: The Cost of Relativity
    ... >>relativist idiot misprogrammed them and the need constant correction to ... adjustments for relativity. ... the atomic clock in each satellite, so the signal from a fourth ... If they mean actual time values are sent to the Earth clock then the ...
    (sci.physics)
  • Re: The Cost of Relativity
    ... >>relativist idiot misprogrammed them and the need constant correction to ... adjustments for relativity. ... the atomic clock in each satellite, so the signal from a fourth ... If they mean actual time values are sent to the Earth clock then the ...
    (sci.physics.relativity)
Quantcast