On Mon, 05 Jan 2009 09:40:21 -0500, Dave Brown
wrote:

Does anyone have any experience with working the GPS from the centre of
a moving vehicle? Does it need to be near glass to receive signals?

As a general rule, yes.

You can receive signals away from windows depending on where the
constellation is at any one given time, but that can be a hit or miss
situation. If it's located near the floor, probably not. If it was
sitting on your lap though, it will work, but not with the same
accuracy - it all depends on the location of the constellation at the
time, where the GPS is located, etc.

There are situations where even situated near glass it will struggle
with finding satellites - something about how the glass is coated or
the composition of the substrate film used to make safety glass. Some
RFI devices (like Easy Pass transponders) don't work on certian cars
for that reason.

I can receive GPS signal in the middle of my house - then again, I'm
located fairly high and it's a one story ranch.