A gps tracklog is a collection of track points along the course of a route. It’s essentially a bread crumb trail of the path of the route to be navigated. Tracklogs can tell us where we have been and therefore how to get back to where we started. More importantly, if prepared in advance, a tracklog can tell us where we need to go.
Tracklogs are most often created by a GPS instrument as the user navigates a desired route or path. It’s a recording of the path navigated. Not all GPS instruments utilize tracklogs. Some instruments only give the user an active tracklog with no ability to save the tracklog as an individual file.
The various GPS instruments handle tracklogs in different ways. Even within a manufacturers product line, the tracklog functions are different mainly due to product evolution. Some instruments only allow the user to work with an Active or Main tracklog. Other units allow the user to save tracklogs.
The Garmin GPS III+ and earlier units do not allow tracks to be uploaded to saved logs, so all uploaded tracks go to the main or active tracklog. It’s important to remember to save each individual tracklog from the Active log if you intend to have multiple tracklog files available on the instrument.
There are limits on how many track points can exist in a tracklog file. Many units allow more track points in the active log than the saved log. When a tracklog is saved the number of track points (resolution) is reduced to a number less than or equal to the maximum number of units allowed for a saved log. Early Garmin units allowed 250 track points in a saved log. Some of the higher end units like the Garmin 176C allow for 500 track points in a saved log file.
On the later Garmin units, you can load tracklogs directly into saved logs in the gps instrument. These files must not be over the maximum number of track points otherwise the file will be truncated. It’s a good idea to have tracklogs stored on your computer in a reduced format (less than or equal to the maximum number of track points allowed in a stored tracklog for the intended instrument).
Also, you must keep in mind that any track uploaded which does not have the name ACTIVE LOG will be sent to a 'saved track' log on the Garmin units capable of uploading to stored log files.