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From: Arno Welzel <usenet@arnowelzel.de>
Newsgroups: comp.mobile.android
Subject: Re: What can't you do on Android WITHOUT a Google Account set up in
 the OS?
Date: Fri, 10 Jan 2025 18:14:25 +0100
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VanguardLH, 2025-01-05 18:34:

> "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.  

A magnetometer has nothing to do with GPS.

> 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.

A-GPS only reduces the time until you have a GPS fix but it will *not*
improve accuracy. In addition to A-GPS Android also uses triangulation
of known cell towers and WiFi networks to determine the current position
when possible.

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

There is no "GPS re-calibration". A GPS reciever can not be more or less
acurate depening on any kind of "calibration". There are units which are
more acurate than others and GPS signals can become inacurate when you
have a lot of big objects around you, like trees, houses and so on.

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

Do you read your own sources?

Quote:

"Assisted GNSS (A-GNSS) is a GNSS augmentation system that often
significantly improves the startup performance—i.e., time-to-first-fix
(TTFF)—of a global navigation satellite system (GNSS). "

And that's it - faster positioning fix, but not better accuracy.

So with A-GPS or A-GNSS the GPS receiver will know what satellites are
visible at all at its current positions and does not have to wait to get
the information with the slow downlink stream via GPS which is only
around 50 kBit/s - which can take up to 12.5 minutes.



-- 
Arno Welzel
https://arnowelzel.de