On 2 Sep 2004 at 11:19, alex wrote: > I think (have to turn it on, and wait for a while) that my Garmin can > show 15 ft accuracy, which is 4.5m. There are additional (or > different) satellites to achieve such increased accuracy, called WAAS. > But not in all areas. I've seen such accuracy displayed quite often, > and didn't notice it to be incorrect, though such accuracy exceeded > that of the built-in map :-). Sorry, my GPS is pre-WAAS so I never consider those things. You're correct - with extras like WAAS or DGPS, you can get increased accuracy. You also have to consider that some GPS units will do averaging of a position over time - taking lots of readings to cancel out the errors. My comments should be considered in terms of basic GPS functionality when the unit is just turned on. Under those conditions, the basic position error is <15m, 95% of the time. The latter pretty much describes how I use my GPS. It's off almost all the time, but I may turn it on, take a reading and turn it back off. In fact, I only bring my GPS for a long trip or in an unfamiliar area. > And, yes - GPS can be used as a subsitute for compass (but it should > be a supplement, - there is no excuse not to carry at least $5 > around-the-neck compass). Even GPS without a compass can display a > bearing to some map point or waypoint. If you're picking up a GPS for the first time, make sure you know the difference between a GPS with an electronic compass and a GPS that figures out direction based on motion. If you don't have an electronic compass, the compass direction indicated by the GPS relies on the GPS moving at a significant speed to interpret compass directions based on relative locations of adjacent position readings. If you're sitting still or moving very slowly, the apparent compass orientation may be meaningless. A lot of paddlers I know stop paddling to confirm locations with map and compass. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Thu Sep 02 2004 - 14:42:52 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:31:17 PDT