morris

Moeilijkheidsgraad   Gemakkelijk

Tijd  één uur 44 minuten

Coördinaten 501

Geüpload 13 februari 2008

Uitgevoerd mei 2007

-
-
94 m
3 m
0
6,3
13
25,38 km

4202 maal bekeken, 109 maal gedownload

nabij Nederzwijnaarde, Oost-Vlaanderen (Belgique)

3 commentaren

  • Foto van VIM

    VIM 10-apr-2008

    Hello morris!
    (Ik ga verder in het Engels omdat ik begot niet weet welke je moedertaal is. Ik stelde voor aan de beheerder van Wikiloc om dat in onze profielen te laten opnemen voor als we eens kommentaar willen geven... zoals nu).
    Although this is a circular track, the starting point has an altitude of 160m and the end point is at 13m. The last point in the track is even at -23m: hope the GPS did not fall into a deep pit ;-)
    Is there something wrong with the uploaded file or with Wikiloc?

  • morris 10-apr-2008

    Hi,
    We could continue in Dutch, but maybe somebody else is also interested in the reply, so I'll continue in English:
    The track is captured with a Garmin GPSMap60CSX, a device with build-in pressure/temperature based altimeter. So next to the altitude as measured via a GPS-signal, it takes into acoount changes in air pressure and temperature to measure more acurately height changes.
    In order to have, from the moment you switch on the device, a good altitude measurement, you should callibrate the altitude by typing in the correct altitude. If you don't do this, the device might measure wrongly the altitude (eg you get out of a warm car, temperature drops so the device thinks you are higher)
    But how is it possible that at the end of the track the height is correct ? Well, because the device callibrates itself, over a longer time, via the GPS-height it receives from the sattelites.
    To summarize: the absolute altitude comes from the GPS-signal, changes in height come in first instance from measured changes of temp/air pressure, and this meaurement has priority, but is corrected over a longer time via the GPS altitude.
    Hope this clarifies,
    Morris

  • Foto van VIM

    VIM 10-apr-2008

    Hello Morris,
    (Will continue in English too!)
    Now I understand the reason.
    I too used to have a (ETrex Vista) GPS with a built-in altimeter.
    And indeed: I had to calibrate it each time I switched it on at a new location in order to have correct altitude readings during my trip.
    But even then: if the barometric pressure was changing fast, my recorded track altitudes were often further away from reality then by using the GPS altitude.
    That's why, when I switched to a GPSMap60C, I chose a model without altimeter, just because I had little profit from such a device. On the other hand; the built-in compass of the ETrex was useful when standing still.

    ANYHOW: will certainly download some of your tracks as they look promising!