[time-nuts] Advantages of GNSS ???

[Michael Wouters]

Hello Luiz,

(Did we meet at IFCS-EFTF in Orlando? If so, my apologies for not
remembering your name, and for repeating here what you know). I presented
some preliminary time-transfer data for the F9P at IFCS and wrote a short
paper for the proceedings; if you’d like a copy, I am happy to send you one.

For any other time-nuts interested in post processed GNSS time -transfer:

Since the conference, I have been working on and off on adding dual
frequency support to OpenTTP ( www.openttp.org), principally for the F9P/T
and have four F9P receivers under test. The aim is to have a nice long data
set for EFTF next year.

Cheers
Michael

On Sat, 6 Jul 2019 at 2:02 pm, Luiz Paulo Damaceno <
luizpauloeletrico42 at gmail.com> wrote:

> 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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