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Re: [RC] Accuracy of GPS - Jim HollandYes, it WILL follow you down into the ravine and out of it, depending on the quality of the GPS you're using and bird visibility. Since Selective Adaptability has been turned off, my Garmin GPSIII is amazingly accurate, even over mountainous terrain...as long as it can see at least 4 birds. It will tell you with an on-screen message whether it is in "2D" mode or "3D" mode. As long as it can see 4 or more birds, you will get Lattitude, Longitude and Altitude. The accuracy of the GPSIII approaches that of the old Trimble Commercial Units. I doubt that many people ride as many hills as I do. I have tested on rolling mountain clear cut (good reception) with the GPSIII, then checked it with my truck. It provides great repeatability...it was as consistent as my truck odometer over 15 miles. They key is you MUST BE ABLE TO SEE 4 BIRDS CONTINUALLY. If I take it down into the valleys with rock walls and tree cover, the accuracy drops off significantly...almost useless in heavy cover. (It shows you on-screen a graphic of each bird and it's signal strength) A powered helmet antenna adds to the accuracy, but they eat batteries and for normal purposes, IMHO, are not worth the trouble. In addition, the GPSIII has built in Topograpical Maps that actually SHOWS you where you are on the map. Think Hertz Never-Lost on a Topo Map. <grin> I don't know the how sophisticated the Timex Watch is, but if it has the Garmin GPSIII guts, it WILL track 3 dimensional distances, if bird reception is good. Jim, Sun of Dimanche, and Mahada Magic k s swigart wrote: April said:Yeah, I'm saying that if properly set up, the GPS will measure the distance traveled into the ravine and out of it. If the GPS is taking a waypoint measurement every 5 minutes instead of every 5 seconds, you're going to get very different mileage. And the 5 second one is more accurate because it will follow you down into the ravine.No, it won't. The GPS distance traveled measurement does not take altitute into account in its calculations. It assumes a straight line between the two points on a flat plane that it measures. So it won't "follow you down into the ravine" it will assume that each point it took (even if it takes you longer than 5 seconds to get across) that you were not going down and back up again, but rather that you went "as the crow flies" between each of its measurements. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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