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

[kb8tq at n1k.org]

Hi

Unfortunately there's a bit more to it than what the RTK stuff handles. 

A quick simple / easy approach for this sort of thing is to do post
processing of RINEX files through one of the various outfits that does that
over the internet. Depending on where you live, that may be easier or less
easy to do.

A Trimble NetRS is an "oldie but goodie" way to get started. 

Time out of a "conventional" GNSS receiver is subject to a lot of issues.
The post processing and the phase locked clock in the NetRS (plus the dual
band operation) get you started on taking care of them.

Bob

-----Original Message-----
From: drew wollin via time-nuts <time-nuts at lists.febo.com> 
Sent: Sunday, April 27, 2025 4:52 AM
To: time-nuts at lists.febo.com
Cc: drew wollin <drew_wollin at hotmail.com>
Subject: [time-nuts] Does cm accurate GPS via RTK give more accurate time?

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_v
iew/
[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.spar
kfun.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/p
rint_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>
This portal (Geoscience Australia Portal Core) provides full access to
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project requirements.
portal.ga.gov.au

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