[time-nuts] Re: Reducing time-interval noise with RNCAN PPP?

[John Ackermann N8UR]

That's an interesting question, and I'm interested in what other might 
have to say.

The first question is, are you thinking of using RTK for real-time 
correction, or post-processing for after-the-fact?

If real-time, you might want to look at Ole Petter Ronningen's work 
about using PPP RTK (not necessarily NRCan) to make an extremely good 
GPSDO -- check out https://www.efos3.com/GPSDO/GPSDO.html (and he has 
some other very informative pages as well.  That project isn't quite 
what you're asking about, but it's close enough to give you some 
starting points.

If post-processing, you can extract clock offset data from the NRCan 
results that will let you see your local clock performance compared to 
the GPS constellation with time lags from a few hours for the 
ultra-rapid corrections to about 17 days for the final corrections.  I 
think the shortest measurement interval that NRCan PPP supports is 30 
seconds.  From what I can determine, the noise floor of the measurements 
is in the mid e-13s at 30 seconds, improving with longer intervals at a 
-1 slope.

If you're brave enough to unsolder the top of the ZED-F9T module, you'll 
find a 64-ish MHz TCXO.  Replacing that with a signal synthesized from a 
better standard might (and I stress "might") provide better short term 
performance.  It's not an experiment I've tried!

John
----


On 10/16/22 02:55, Marek Doršic via time-nuts wrote:
> Hi,
> 
> I am measuring time-interval between Ublox RCB-F9T PPS ouput and another clock (e.g. Cs clock), where Ublox is set to time mode with fixed surveyed antenna position and data from time-interval counter are corrected for quatization error using ublox TIM-TP receiver message.
> 
> How can results from RNCAN PPP procesing be used to further reduce noise in the time-interval data?
> 
>     .md
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