[aprssig] GPS Signals in a Tunnel?
Stephen H. Smith
wa8lmf2 at aol.com
Sun Nov 25 18:31:40 EST 2007
Ralph Milnes wrote:
> I'm curious -- while driving through the Lincoln Tunnel (New York City) the
> other day, my GPS seemed to be accurately tracking where I was in the
> Was it really getting some GPS signals? How?
> I'm pretty sure my 2m APRS beacon didn't make it out of the tunnel, however.
Most GPS devices will dead-reckon for 15-30 secs when they loose the
satellite signals. Typically, in a tunnel, this would tend to be the
same speed and heading you were on before you entered since most tunnels
are straight. This would tend to look as through the GPS is still
Stephen H. Smith wa8lmf (at) aol.com
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