Garmin Glo - How many satellites?

Hi. Newbie question.
My Garmin Glo detects up to 20/21 GPS and/or GLONASS birds with good S/N but it never seems to use more than 12 in calculating a fix according to the BluetoothGPS app used for mock position on android.
Garmin support say there's no limit to the number it can use.
Can anyone give me an explanation please?

 

Thanks for the reply. It ties in with what I thought but Garmin Support are saying there is no limit.
I've tried to upload a screenshot and would appreciate any comments on whether the selected 12 sats (solid green bars) are indeed the "best" ones.

I'm very happy with the Glo but just curious to understand how it works.
TIA.
Ken

 

Thanks again.
It seems to me though that some of the satellite choices are a bit strange in the example I attached. There are a couple of overlaps that seem to offer no advantage that could be swapped for other satellites and give an improved fix.
Or am I missing something else?

 

I've watched the dynamic situation and it seems that if one of the 12 satellites "in use" is lost, one of the others is immediately substituted and its block goes solid colour. So its data must already be acquired. If the satellite is visible but no data is acquired it appears as shown on the attached. See numbers 30 15 18 & 50.


So it appears that the Glo just picks what it regards as the best 12 and keeps the others on hot standby.
It just seems to me that it isn't always selecting the best 12!
It's a pity that Garmin don't seem to have this publicly documented and indeed their own support seem to think there is no limit to the number of satellites it uses in computing the fix.
There is a noticeable improvement in accuracy between using 8 and 12 satellites so I'd expect some further, albeit smaller, improvements going from 12 to say 16 or 18 and still have some in reserve.