Track distance

You can't change how your device, Basecamp or Mapsource calculate the differences. Small variations are not uncommon and can be due to numerous reasons.

I suspect that over the years Garmin Support has spent an incredible amount of time dealing with the question “Why is the distance on my device different from the value seen in BaseCamp/MapSource?” Recently, they have added a header to tracks that copies the summary data seen on a device. There have been some problems which I suspect they are still addressing. Anyway, MapSource predates the gpx extension that added the device summary data, so it ignores it and calculates everything based on the data stored in the Track. This is why it gives a different result from BaseCamp and your device and why your device and BaseCamp give the same numbers.

The Track data differs from the device summary data because of the number of points used. Devices are capable of updating positions every second. So, the moving time in seconds represents the maximum number of points used to determine distance on the device. This will be far larger than the points in most Track files (unless you set your device to log every second). The GPS does not give true positions. If you were to walk a straight line and then look at the track, you would see that the track is not a straight line. These deviations add error to the total distance and the more points, the larger the accumulated error.

To bring your stored data inline in BaseCamp with what you see in MapSource, all you need do is delete a single point and the summary data will be recalculated based on the saved track points. (There was/is and issue with stopped/moving time that may affect results if you had actual non-moving time in your activity). What point to delete? I would choose one that was obviously off or one along a section I considered to be straight.

No, you can’t change the real-time interval on a device, so the summary data on a device will show a longer/less accurate distance than the logged track data (exceptions being the track logging every second or possibly the track of a stationary position).

This is excellent information, thank you, BTLAAKE.

When I run or ski, etc. with my friend who uses Garmin GPS of Forerunner series, his track distance shown on the device is shorter than mine. Does it mean that the unit does not update its position as frequently as my Fenix?

Many devices can be set to update on time, distance or on auto. On time or distance various times/distances can be set, so unless the 2 devices are working on the same settings there will inevitably be a difference, and even if they do use the same settings there will still be a variation as the devices won't calculate exactly the same position each time.