[time-nuts] Thunderbolt code phase measurement

[Michael Wouters]

Hello Mark

By "hosing" do you mean that you lose messages for the next second? That
was a problem with the Resolution T too. I wanted to get ephemerides from
the receiver so I ended up minimising lost messages by tracking satellites
as they popped into view, and then requesting an ephemeris after a suitable
wait. This problem went away in the SMT 360.

Regard resolving the ms ambiguity, you could look at the code in mktimetx,
which does just what Magnus D describes.
The code lives at
https://github.com/openttp/openttp/tree/master/software/gpscv/common/process/

Cheers
Michael

On Wed, 16 May 2018 at 4:02 pm, Mark Sims <holrum at hotmail.com> wrote:

> Many thanks Peter for confirming what I suspected.   The problem with the
> Trimble receivers is that requesting the satellite C/A code data can hose
> up a lot of them.  So, I'm stuck with calculating the integer number of
> milliseconds.   How to do that?  I do know my position to a few feet.
>
> I have Lady Heather generating RINEX files for the Ublox timing receivers,
> the NVS-08, the Furuno GT-87, and the Ashtech Z12 (with both L1/L2 data).
> It would be nice to be able to support the Trimble receivers.   With L1
> only data I am getting results in the < 200 mm range.  The Z12 with L1/L2
> data gets me to around 40 mm.
>
> ----------------
>
> > If you know your position to within 150 kilometers (0.5 ms), you can
> dispense with the pseudorange-assembly arithmetic and just use the code
> phase directly, after adding in the appropriate integer number of
> milliseconds, only one of which will put you within your known
> 300-kilometer-diameter (1 ms) sphere.
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