Re: [gpsd-users] Using a known location instead of WAAS/GLONASS/RTK/... for corrections

[Greg Troxel]

"Jobs, Steve" <address@hidden> writes:

> Is it possible to pass a know location to gpsd and have it use that
> for error correction?  I may be asking this question wrong so allow me
> setup the scenario.  I have two matching receivers, in this case
> LS20031, one of which will be a base station and the other will be on
> a rover.  Both will be running their own instances of gpsd.  The rover
> will never travel more that 400 feet from the base station so they
> should almost always be sharing the same satellites.  If I place the
> base station at a known location can I just find the difference
> between the signal and the known location and pass that to the rover
> as the correction? Or even better would be to have the base gpsd take
> the known position and then the rover could query the base gpsd for
> the correction and apply it to the signal it has received from its own
> gps receiver.

Basically to do differential one has to compute the errors in the
individual pseudoranges.  Trying to compute errors from the computed
solution is not robust against choosing different satellites.   There
are receivers that will generate corrections, and one can in theory do
this with receivers with raw data outputs, but most cheap receivers do
not do this.

You won't really be sharing the same satellites unless you have the same
obstructions.

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