The following trackpoint elements and attributes are supported:
| TPX Name | Description | Name | Type | Units | Resolution |
|---|---|---|---|---|---|
| Time | Date + Time | ts | float64 | s | 1 x 10-3 |
| LatitudeDegrees 1 | Latitude | lat | float64 | deg | 1 x 10-7 |
| LongitudeDegrees 1 | Longitude | lon | float64 | deg | 1 x 10-7 |
| AltitudeMeters 2 | Elevation | ele | float64 | m | 1 x 10-3 |
| HeartRateBpm | Heart Rate | hr | uint16 | bpm | - |
| Speed 3 4 | Speed Over Ground | sog | float32 | m/s | 1 x 10-3 |
Notes:
It is worth noting that TCX files will sometimes include as many as 16 decimal places for longitude and latitude. This is simply an artifact of the floating point arithmetic used by Garmin Connect, whilst generating the TCX file.
GPS / GNSS chips typically output the equivalent of 7 decimal places. For example, SiRF and ublox binary formats both provide latitude and longitude with exactly 7 decimal places.
7 decimal places provides a resolution equivalent to 1.11 cm at the equator so it should be easy to see that providing more than this level of precision is highly misleading, given the accuracy of GPS technology.
Elevation is recorded to the nearest 0.2m in Garmin TCX files and the same resolution in FIT + GPX files from Garmin Connect.
However, TCX files from Garmin Connect will often show as many as 16 decimal places despite the true resolution being 0.2m.
This spurious precision is ignored by the GPS Wizard when it loads TCX files into memory.
Garmin added support for speed in ActivityExtensionv1 and ActivityExtensionv2 for use with TCX.
It should be noted that the native TCX units are m/s, but COROS are using km/h. This is obviously a bug on the part of COROS.
The TCX schema clearly draws some inspiration from the GPX schema. There are however some fundamental differences in structure, primarily around the concepts of activities, laps, and tracks.
GPS Wizard is capable of reading TCX files which contain multiple activities, including multisport activities. Each activity within the TCX is simply treated as a separate track by GPS Wizard, so a single TCX may be regarded as containing multiple tracks.
Laps have no meaning within GPS Wizard, so an activity within a TCX file is simply a single track containing a collection of track points. De-duplication has been implemented, such as when the last point of one lap is identical to the first point of the following lap.