Whats the difference between the .gpx files and .NMEA files?
Which is the best one to use with RealSpeed?
NMEA has doppler info as well as trackpoint data, wheras GPX only has trackpoint (I think!)
Use NMEA, or if you've got a NAVI then use .SBN -- SBN is a binary format with better precision.
That's my understanding anyway, happy to be proven wrong.
For practical purposes that is pretty close.
Actually, .GPX file format can contain all the NMEA data if it is available from the GPS but in practice the Garmin GPS's produce .GPX data without the extra satellite, HDOP or Doppler data.
The .SBN and .SBR formats from the GT-11 are best to use in RealSpeed (and other programs) because, as Nebbian says, they contain data with more precision (to more decimal places).
Also, RealSpeed processes the .SBN and .SBR formats faster than .NMEA
As an aside, RealSpeed can save the other file types in the .GPX format and of course it then contains the same precision and data as the original format.
Bottom line: if you have a GT-11, best to use the .SBN or .SBR file format.
Thanks for that 
I have been using the NMEA data but will probably start to use the .SBN files now. May as well use the most accurate one.
If you want to load your track onto Google Earth, i think you can only use .gpx files. So just save it somewhere else as that different format if you want to look where you have gone that way. Thats how i work it anyway. However when you quit Google Earth after loking at a track, do not to click the yes button to save. Thats what i have been told so i figure just listen to the pros lol.
Cheers
Bubs
