[time-nuts] Advantages of GNSS ???

[Graham / KE9H]

I have several questions for the group, since there are several members
that have been able to start evaluating the uBlox F9P and perhaps the F9T
GNSS receivers.

For the purposes of time and frequency determination, is there an advantage
to using the GNSS receivers, relative to just the US GPS?

It appears that a really good GPS (only) based GPSDO can get into the 1e-11
and perhaps the 1e-12 accuracy range.

Does using the signals from GPS (USA), plus GLONASS (Russia), plus Beidou
(China), and plus Galileo (Europe), actually provide any improvement in
time/frequency accuracy?

Is that what the F9P actually does, or only some sub-combinations of the
above?

Down at that level of accuracy, do the four systems agree within 1 e-12,
anyway?

Is there any advantage to using the GNSS for time/frequency?

Does using the RTCM Corrections, needed to achieve the ~ 1 cm positioning
accuracy also improve time/frequency accuracy?

The underlying question I am trying to get at is: Will a GNSS based GPSDO
have any advantage over a GPS-only, or a dual band L1/L2 GPS-only GPSDO?

Thanks,
--- Graham

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