[time-nuts] Advantages of GNSS ???

[Luiz Paulo Damaceno]

Hey Graham,

I'm gonna start a project soon to evaluate a F9P as a Time Transfer GNSS
receiver. For now i haven't too much answers for you but only i know is:
the BIPM uses all labs that participate from UTC to make corrections of
GNSS satellites frequency, also for the TAI use. I think GNNS T&F is a good
and reliable source for many projects. Here in my lab with Septentrio's
Pola RX 3 Tr we have a very low Time Dilution Of Precision when the Glonass
and all anothers becomes enabled, so our frequency if compared to all GNSS
constallations is good, i think the same logic can be applied for frequency
generation / distribution. What i want to say is: with more satellites of
different constellations you can have a better end signal (more stable and
reliable). Tests should be done. I hope can help more in the future.

Best regards,

Luiz

Em sex, 5 de jul de 2019 às 23:00, Graham / KE9H <ke9h.graham at gmail.com>
escreveu:

> 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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