To continue this thread:
I bought a new Aokatec GPS modul G750 for my D750.
My older version has the previous GPS receiver "u-blox M7" built-in.
The new one has the GPS receiver "u-blox M8".
The M8 has a better sensitivity and therefore a faster satellite tracking.
And the M8 receives simultaneous GPS and GLONASS satellites.
Furthermore it is supposed to has a more stable satellite reception.
I gave the older version to my friend but he damaged it during
a transport in a photo bag. The connection is broken.
That is the reason, why I protect it by a L-bracket.
But now we know the inside of the Aokatec module
Before he damaged it, we could compare both versions.
And indeed the M8 version is faster for the first satellite tracking.
M7, outside in the field, 30-50+ seconds
M8, outside in the Field, 25-35 seconds.
That is not such a big difference, but in the house the M8 found
without problems satellites, the M7 didn't.
That means in critical situations, e.g. in the city with it's high
buildings, the performance of the M8 will be better.
The disadvantage is, that the M8 version don't has anymore
the compass function.
If you have already a G750 and no compass, you can be sure
it's the M8 version.
Who is interesting in technical comparison M7 vs M8:
https://www.u-blox.com/sites/default/files/products/documents/u-blox-M8-7-Multi-GNSS_WhitePaper_%28UBX-14002009%29.pdfGreetings
Thomas