Edge 800 or Basecamp data - which is right?

Former Member over 12 years ago

When comparing history on my Garmin 800 with the corresponding data imported into Basecamp, there is a discrepancy. For example, today 9.64 miles covered on the Garmin appears as 9.9 in Basecamp; max speed of 24.6 becomes 24. On another trip average moving speed is 9.3 on the Garmin, 10mph on Basecamp.

Which should I trust?

Ian

0 SUSSAMB over 12 years ago

Basecamp rounds up/down so both are 'correct' but the Edge is more exact :)

0 Former Member over 12 years ago

Thanks. Not sure that I'd consider the "rounding" Basecamp is doing as either logical or consistent. What happens with DIY Audax data - how would you turn the .fit file into an 'accurate' .gpx?

0 BTLAAKE over 12 years ago

SUSSAMB may well be correct, but it looks a little odd for rounding errors. I am not at all familiar with the Edge line or what types of files it stores. I am also not sure exactly what you are referring to by device vs. BaseCamp. But here are some questions off the top of my head you can think about:

Does device mean real time display?

Is the real time display purely gps data or is it based on a sensor (I have no idea if sensors are applicable, but it would be an interesting idea to incorporate)?

What is downloaded to BaseCamp (a gps track)?

Real time display vs. a stored file for purely GPS data will differ if one logs more points than the other (real time data may update every second, while the saved data is less frequent). More points will translate to a longer distance. The GPS distance should be greater than the true distance.

If the device is displaying data based on a sensor (wheel radius/diameter and revolutions) and downloading a gps track, then you are looking at results obtained by two different methods with different associated errors.

0 SUSSAMB over 12 years ago

SUSSAMB may well be correct, but it looks a little odd for rounding errors.

Looking at it again I think you're correct and I'm wrong, didn't look closely enough at all the figures, think I must have done it on my phone and probably misread some of them :(