General question about having 2 GPS sources on the same device and seeing different results

[ovizii]

I found a new GPS app and liked the queueing feature, so I considered switching to it (its named colota) from OwnTracks. I am using geopulse as my backend to store and visualize this data. Since it is able to separately manage the GPS data of different trackers so for a first test to see how colota's battery consumption compares to OwnTracks, I set colota up in parallel with Owntracks and the same settings.

I was quite surprised to see both apps reporting GPS data at almost the same time but with wildly differing accuracy. Sometimes even different altitude data and speed.

Any idea what could cause this? To my understanding, GPS data is collected by both apps directly from the phone, so what could cause this? Not interested in app comparisons, just want to understand where these discrepancies come from?

Here is a sample where colota's results look better, but it randomly changes between the two tools. Are they interfering with each other maybe?

Here is a sample with fluctuating values being reported. The slow speed is accurate, this is me walking my old dog so any speed above 4 km/h is wrong and differences in altitude are also wrong. We covered about 800m on flat terrain, no GPS obstructions around, phone in my hand.

[tess1o]

Hello,

I'm not a mobile developer so this answer might not be correct but I guess that all apps are not allowed to send background data when they want. Android OS in this case allows some time windows when it wakes app the apps and allows them to do network activity in background (send gps data to geopulse). Maybe GPS data is collected by different apps in slightly different time but they send it when allowed by the OS. Probably it's better to check with the Colota developer.

[ovizii]

Thanks for your reply, it was just a stab in the dark asking here :-)

I got a pretty detailed answer over here from the author of colota (an Android GPS Tracker).