At 8:02 AM -0400 8/26/99, Bill Gunshannon wrote:
>I wouldn't think GPS was legal for most TSD rallyes. Is it?? I have
>played with GPS using both a laptop and a PalmPilot and it seems to me
>it would be a tremendous advantage over a speedometer/odometer that is
>in most cases not even close. Heck, how much air you have in your tires
>can effect it's accuracy. With GPS and my Palm (with no maps loaded) I
>can get extremely accurate speed/distance measurements. You get time too,
>but even my watch is accurate enough for that part.
Funny that this should come up now; the question was raised the other day
on the rally mailing list as well. The bottom line is GPS is not all that
accurate for rallies. The signal is dithered for civilian use, producing an
accuracy of +/- 100 meters. If you use DGPS, the accuracy improves, but my
rally computer will display mileage to 0.001 miles and time to 0.001
minutes. Getting a good factor is the challenge when rallying with a
computer and good teams strive for 1/2 point per control, where 1 point is
0.01 minute error.
Phil Barnes
Cortland, NY
peb3@cornell.edu
|