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

[dk4ww at gmx.net]

Hi,

F9T need RTCM from F9T RX. Have a look to Manual.
Works fine.

cheers 
Uwe

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Am 17.10.22 um 13:20 schrieb Marek Doršic via time-nuts

> Hi,
> 
>     to you first question, real-time RTK would be fine, but as far as I know and tested F9T does not accept RTCM streams.
> So I am aimimg for the post processing with PPP or PPP-RTK as I have at hand observation data of a near-by static geodetic reference station.
> 
> I already analyzed the NRCAN output clock file, but It gives same information as the ublox NAV-CLOCK message in real-time. So I assume, ublox FW is already using this local clock offsets in the routines for generating output PPS and qErr.
> 
> BIPM uses GPSPPP program or there is Atomium in ORB (Belguim), anybody as access to it and the experience?
> 
> Replacing the ZED-F9T oscillator is nice experiment, but for now I have only one and I would like to stay with of the shelf products. Maybe I try with an older M8T.
> 
>    .md
> 
> > On 16 Oct 2022, at 17:10, John Ackermann N8UR via time-nuts <time-nuts at lists.febo.com> wrote:
> > 
> > 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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