On Mon, 05 Jan 2009 17:01:19 -0500, Tom Francis - SWSports
wrote:

On Mon, 05 Jan 2009 18:04:26 GMT, (Richard
Casady) wrote:

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?

Metal blocks all radio.

As a strict statement, that is true, however radio signals can bend
around objects (demonstrated by radar's ability to see behind
objects). As such a car presents the opportunity to receive signals
inside by virtue of the physics of radio wave propogation and the
ability to move along the surface of metal.

The only way to completely restrict the reception of radio signals is
to build a grounded solid metal box of some sort or use a grounded
fine wire mesh in which the gaps are less than 1/100th of the base
line wavelength.

That is true enough, but you generally need to have a view of the sky
unblocked by solid metal. The closer to the glass, the more signal you
get. No problem in an open boat, or inside a fiberglass pilot house.
Now tell how me the cell phone worked inside a steel ship a thousand
miles from land. Magic, obviously. Nothing on the bill from either the
ship or the phoneco, so it must have been magic.

Casady