[time-nuts] Re: Does cm accurate GPS via RTK give more accurate time?

[Ole Petter Ronningen]

Hi

As far as I know, the clocks cancel out in the RTK equations:
https://gssc.esa.int/navipedia/index.php?title=RTK_Fundamentals

Meaning; no better time from RTK itself.

BR
Ole

On Sun, Apr 27, 2025 at 6:09 PM drew wollin via time-nuts <
time-nuts at lists.febo.com> wrote:

> Hi All
>
> I have a long-term interest in GPS/GNSS for accurate position, frequency
> and time.
>
> Conventional GNSS receivers are accurate to a few metres and about 10
> nanoseconds.
>
> The accuracy can be improved by using correction information via RTK over
> the internet. The receiver needs to be within about 20 km of an RTK base
> station. The RTK base stations are linked and available as government or
> private correction networks, some of which are free. See the link for the
> Australian RTK network.
>
> The RTK corrections are based on local space weather and the ionosphere's
> effect on the received satellite signal.
>
> It is relatively inexpensive and easy to use these networks to get cm
> accuracy positioning. U-blox and Quectel make RTK-capable receivers, which
> are available from SparkFun and AliExpress. The receiver boards from
> AliExpress cost around US$50.
>
> The receivers can be used with software from the respective manufacturers
>
> With centimetre position accuracy, presumably, time pulse accuracy also
> improves. Does anyone know if that is the case? I looked on the web without
> success
>
> The Quectel LG290P has a 1 PPS output that could be connected to other
> timing equipment.
>
> I have an SRS PRS10 GPSDO cesium clock with an early single-satellite GPS
> receiver. I was thinking of replacing it with a 1 PPS signal from an
> RTK-corrected LG290P.
>
> The other question, of course, is how do I measure if the time is better?
>
> Regards Drew VK4ZXI
>
> https://portal.ga.gov.au/persona/pa
>
>
> https://docs.sparkfun.com/SparkFun_LG290P_Quadband_GNSS_RTK_Breakout/print_view/
> [
> https://docs.sparkfun.com/SparkFun_LG290P_Quadband_GNSS_RTK_Breakout/print_view/%22https://i.ytimg.com/vi/a-aU4-Yodzg/default.jpg%22
> ]<
> https://docs.sparkfun.com/SparkFun_LG290P_Quadband_GNSS_RTK_Breakout/print_view/
> >
> Introduction - SparkFun LG290P Quadband GNSS RTK Breakout Hookup Guide<
> https://docs.sparkfun.com/SparkFun_LG290P_Quadband_GNSS_RTK_Breakout/print_view/
> >
> The SparkFun Quadband GNSS RTK Breakout - LG290P (Qwiic) features the
> Quectel LG290P GNSS module. The board's dimensions, pin layout, and
> connectors are exactly the same as our vary popular SparkFun GPS-RTK-SMA
> Breakout - ZED-F9P (Qwiic); and can be used as a drop-in replacement.The
> board also accommodates users with a diverse choice of interfaces including
> UART, SPI 1, and I 2 C 1.
> docs.sparkfun.com
>
> [https://nonprod.portal.ga.gov.au/cache/images/portal_ga.png]<
> https://portal.ga.gov.au/persona/pa>
> Geoscience Australia Portal<https://portal.ga.gov.au/persona/pa>
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