Accuracy of track statistics and inaccurate track exchange

Hello guys,
on weekend i recorded a MTB track. When I checked the track details I got some unexspected behaviour:

- Max. speed of the track is 49,8 km/h. When I look trough the parts of the track I get a max. speed of 42,5 km/h.
How this can happen ? What is the correct max. speed ?
- When I do an upload to trainingstagebuch.org and compare the track details elevation gain and the distance slightly differs. Whats the reason for this?
- When I send the track to via GXP export to my girlfriends oruxmaps I get huge difference in the track details when opning the track there. It is not a slightly difference(~ 5m difference in elevation gain). There are big differences in max. speed (about 10%), in elevation gain/loss(around 30m until 50m) and small differences in the distance. How this can happen? Is there a better way to exchange the tracks?

Would be please about any answers!

Best regards,
Patrick

schmpat wrote:Hello guys,
on weekend i recorded a MTB track. When I checked the track details I got some unexspected behaviour:

- Max. speed of the track is 49,8 km/h. When I look trough the parts of the track I get a max. speed of 42,5 km/h.
 How this can happen ? What is the correct max. speed ?
- When I do an upload to trainingstagebuch.org and compare the track details elevation gain and the distance slightly differs. Whats the reason for this?
- When I send the track to via GXP export to my girlfriends oruxmaps I get huge difference in the track details when opning the track there. It is not a slightly difference(~ 5m difference in elevation gain). There are big differences in max. speed (about 10%), in elevation gain/loss(around 30m until 50m) and small differences in the distance. How this can happen? Is there a better way to exchange the tracks?

Would be please about any answers!

Best regards,
Patrick

 
Some tips:

Each data obtained by the application from the GPS provides speed data. This data is used by OruxMaps for maximum speed.

But when you export the track to gpx format/kml, this data, which is the closest approximation to the maximum speed is not used, because gpx/kml has no tags to save this data. When you upload the track to a website (or OruxMaps, if you import the track again) the application must recalculate the maximum speed based on distance/time between each two points of the gpx/kml. This value may be different from the maximum value obtained by the GPS that was saved by OruxMaps.

When you see OruxMaps statistic sections, OruxMaps has also to calculate the maximum speed of each km/mi using each two track points. 

Elevation ascent/descent. Because of altitude inaccuracy of GPS, each website (also oruxmaps) implements algorithms to try to correct this error. So every website provides a slighty different value. But you can use OruxMaps + DEM files to get a value close to reality.

orux