Correct me if I'm wrong, but I was under the impression that the gps receivers
were set up to take their position at 1 second intervals.  Since their time is
set by one of the gps receivers in the sky, then they should have taken the
readings at the beginning of each second, which will be within msec of each
other.

Aside from that, the gps receivers select 4 satellites, one to get the time, and
three the triangulate the position.  Both receivers would have to select the
same satelite for time, and the same three for triangulation, in the same area
for very good correlation.  There is a great chance that they would select the
same four satellites, but not necessarily assign the same roles to the same
sats.

So, yes, I know I'm not going to get great positioning.  However, it will be
significantly better than the 100M the SA affords.

Secondly, 1M resolution is unrealistic(ie, low probability of being within 1
meter of the real position given by the mean of the plots) even if you are
willing to stay in one place for an hour or longer.  You can average and get to
5M accuracy if you take one reading every ten minutes for 24 hours, and after 36
hours you can assume 1M.  After 36 hours the results don't improve much UNLESS
you have a receiver which is significantly better than mine.

More info on position averaging (which seems to be the thrust of your
suggestion) can be seen on sci.geo.satellite-nav in the threads
Position averaging, 7/3/99
Averaging, 7/11/99

-Adam

Anne Ogborn wrote:
>
> Running two sets of data will not remove the SA reliably unless you
> move slowly (much more so than normal mtn bike speed)
> and take LOTS of data, in which case you can ignore the SA
> anyway. The jitter is not directly in the position, it's a time jitter
> in the sat signal. So unless the fixes are within millisec of each other
> and are from the same sats this won't work.
>
> And 1M resolution is unrealistic unless you're willing to stay at each
> station for 1/2 hour or longer.
>
> Hate to disappoint, but this doesn't sound do-able from my experience with
> tracking busses with GPS.
>
> --
> Anniepoo
> Need loco motors?
> http://www.idiom.com/~anniepoo/depot/motors.html