Re: What can't you do on Android WITHOUT a Google Account set up in the OS?

"R.Wieser" <address@is.invalid> wrote:

(1) a test with the GPS of a tablet I had didn't give me much
confidence in its accuracy.

The magnometer periodically requires re-calibration (the 3-D figure 8
roll) to get compass readings correct. 

Similarly, sometimes the A-GPS table needs to get re-downloaded.  There
are lots of GPS apps available, and some have an A-GPS reset function.
I use:

https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2

This is one of those apps that don't have a gear icon to get at
settings.  Instead you drag from the left edge of the screen to get at
its config panel; however, with a armor case on the phone, it is hard to
drag from any edge of the screen.  There is a help page at:

https://mobiwia.com/gpsstatus/

but it presumes you already know a lot about this stuff.  You can swipe
from the left to get the config panel to switch between the Status,
Radar, and Locations panels, or swipe in from the right to move between
them.

This app guides you through the compass re-calibrate.  In its main
screen, there is a bubble you center to get the phone level to eliminate
discrepencies.  It also has a pitch/roll calibrate function.

Its status panel shows to how many GPS satellites you are connected (the
green dots).  The dots, their colors, and shapes is described at their
help page.  If you can't reach the GPS satellites, there won't be any
green circle dots, and a constantly spinning "Looking for GPS location"
message is displayed.

For GPS re-calibration, this app lets you reset the A-GPS table, and
download new data.

https://en.wikipedia.org/wiki/Assisted_GNSS

(2) I never was able to find an authorative source to what this "diff"
file should look like though.

For GPS traces, I'd start here:

https://wiki.openstreetmap.org/wiki/Mapping_techniques

I saw uploaded traces, and where you upload them, at:

https://www.openstreetmap.org/traces

For editing the database, I'd start here:

https://wiki.openstreetmap.org/wiki/Editors

For help from their community, I'd try here:

https://community.openstreetmap.org/

I didn't find (but didn't look that hard) for info on the structure of
the database, or of exported data (which I suspect is XML).  Remember
that I quit using OSMand, so the above is what I found in online
searches.