There are certain technical limitations related to the different ways how data is represented in the file formats. tcx2hrm takes care to perform any calculations necessary with the highest accuracy available. However, depending on the setup the user can significantly influence data accuracy by taking the following tips into account:
- Many Garmin devices support the „intelligent“ data record mode. This reduces the amount of data stored per time unit and saves memory but it is the most common reason for inaccuracy. In contrast to TCX files, HRM files only support fixed time interval data records, hence tcx2hrm must heavily use data interpolation during conversion. Use the per-second mode instead to enable tcx2hrm using the input data directly.
- Stick to metric units, as TCX does not support US units – no matter which unit you selected within your Garmin device. In case you require US units in HRM, a recalculation is necessary.
- Only request a different file version and monitor type for the HRM output, if you really require. The default settings (file version 1.07 and S725X as monitor) provide the most advanced setup and should be applicable for likely any situation.
tcx2hrm supports one seconds interval for HRM output, however this might cause issues with some applications, as the file format specification only supports five seconds interval. Finally in case you stick to the latter, it is worth for accuracy to have more data and generate less than vice versa. However, to be as near to the specifications as possible, five second interval is default.
I’m following those rules, but…
Even you where following the rules above, there is still space for data inaccuracy. This can hardly be prevented, because…
- TCX allows data inconsistencies (non recorded data columns). tcx2hrm does a lot of afford to overcome this.
- TCX stores certain data in different way. E.g. TCX does only record the distance, HRM requires speed. tcx2hrm uses high accuracy methods for calculations, rounding is done according to the file specifications
However, the level of inaccuracy should be considerable low for the application of training data.
For all those guys, who are still not convinced: tcx2hrm uses double precision values (64 bits) for any calculations…