[closed] Number of locations recorded differs between GPS devices

[djonathan]

AlpineQuest 1.4.22 on two GPS Android units, same settings, including 10s recording interval. I walked a short course, no significant stops, one unit says 1.6mi, the other 1.59mi, so lets call that "the same".

One unit saved 172 locations in 25:11min, while the other saved only 122 locations in 24:45min, which brings up two questions. Since a 10s interval over 25 minutes should yield 150 samples, why would the first unit have recorded 172 samples? Since the second unit recorded only 122 samples, what are possible reasons the software discarded about 30 samples?

[Psyberia-Support]

Hi and thanks for your interest in our application.

The recording interval is a guideline that sometimes cannot be exactly followed by the app. For example:

- The GPS chip can temporarily loose the signal from the satellites, so the application do not receive any location update for some time which can be greater than the recording interval. Since the app doesn't "create" missing locations, the final track may have less locations than the expected 1loc/10sec. This is often the case when you're in areas with poor GPS signal (forest, narrow access to sky, sky heavily cloudy, etc) or when using low cost smartphones;

- On the contrary, as soon as the application receive a location with a greater precision than the previous one, it will keep it even if the recording interval is not reached. In this case, you may find more locations than expected. Few other things can also impact the number of locations, like filters.

By browsing the track, you can check the time of each location to get a more precise idea of what's happening.

Finally, 1.6mi and 1.59mi is quite good when using smartphones to track a path. Keep in mind that those devices are not primarily designed as GPS units, usually use cheap GPS chips not always well located inside the device...

Don't hesitate if you have any question.
Best regards