Clarifying my previous question..
There's no doubt that multipath exists, and how to test is fairly
straightforward, whether with multiple antennas, cables, or waving
cookie sheets around..
What I was really asking is if anyone had observed this in the output of
their GPS receiver.
That is, say you were watching the 1pps output and comparing its to your
ensemble of active hydrogen masers.. As you place and remove the cookie
sheet, do you see any (fraction of a nanosecond) change in 1pps?
(unlikely, since I assume the 1pps has a fairly long time constant).
Or more interesting, if you happened to have a GPS receiver that puts
out raw observables of carrier or code phase, would you see a bump? Or
if you were experimenting with your KF implementation, where you were
comparing filter output (i.e. estimate of where it "should be") and
tracking loop output (i.e. "where it is") would you see any discontinuity.
Ultimately, the way to find out is just to get a GPS sampler, record
some raw bits, and then run the correlator and look for the second peak
from the reflection.
There's been a lot of discussion over the years about good and bad
locations for the antenna, and how multipath is a big issue with getting
very good timing performance. I was wondering if someone had a
practical anecdote of better or worse performance that could be
attributed to something on the order of a square meter. (position
inaccuracies in urban canyons are a good example of multipath from
hundreds of square meters)
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