Garmin users. Check out SportTracks. It's great and there's a lot of info about the Garmin 'problem' at start up(elevation jump).Other Garmin stuff discussed. Sadie K, thanks for your help earlier...., I'm a convert now




Posted: Fri May 01, 2009 4:30 pm Post subject:
Question:

Garmin (barometric) devices specific notes?

Answer:

* There is a "noise" from the measurements, the value can toggle +/- 0.48 m on flats. Therefore one second recording gives inflated values. See this thread going into detail. It is established that Edge 305&705, Forerunner 305&405 do record the elevation in steps of approx. 0.481 meters. ALL elevation differences in the ORIGINAL record from one point to the next will be 0 OR a multiple of 0.481 meters. Due to this, notably grade values and graphs might be very inaccurate locally, however, they get reasonable if averaged over some time.
* Barometric changes may give absolute differences (so passing a certain point gives different values each time). The device auto calculates during the ride, but if the pressure changes fast enough, the device will not calibrate enough.
* Beware of the "kludge" when starting - the device syncs the barometric elevation to the GPS height then.
* An elevation "jump" may be observed with an Edge 305 at start of a record. This thread goes into details.
http://www.zonefivesoftware.com/Spor...pic.php?t=6121