[time-nuts] update on SATRE TWSTFT decoding

[jeanmichel.friedt at femto-st.fr]

Dear time-nuts community,
following my end-of-March request for SATRE/MITREX information which led to very interesting
information (https://febo.com/pipermail/time-nuts_lists.febo.com/2022-March/105351.html), I have 
mostly completed Two Way Satellite Time and Frequency Transfer (TWSTFT) signal decoding which might
be relevant to this audience since as a side project I am wondering whether this signal can be of
any use in one-way communication. 

I will be discussing at the upcoming GNU Radio Conference the topic with the video of the
presentation
at http://jmfriedt.free.fr/grcon2022_jmfriedt.mp4 with the slides at
http://jmfriedt.free.fr/grcon2022.pdf 
and the manuscript for the proceedings at http://jmfriedt.free.fr/glmf_satre_eng.pdf (for the
French speaking audience, this is an English translation of http://jmfriedt.free.fr/glmf_satre.pdf
to be published in the special issue of GNU/Linux Magazine France in a couple of weeks). The github
repository is at https://github.com/oscimp/gr-satre

I am still struggling to try and measure the satellite motion to try to compensate its impact on
the
time of flight. I was informed that C. Rieck published a couple of papers on the topic, and indeed
C. Rieck, P. Jarlemark & K. Jaldehag, Passive Utilization of the TWSTFT Technique, Proc EFTF (2018)
does mention "by a GPS ICD [7] compatible Kepler model, which is estimated using iterative
nonlinear least 
squares" which does not tell me much on the technical challenges, with the paper just going on with
results but no way to reproduce the actual computations (of course). [7] is a general specification
of
NAVSTAR/GPS with hardly any relevant information. At about the same time 
C. Rieck, P. Jarlemark & K. Jaldehag, Utilizing TWSTFT in a Passive Configuration, Proc. 48th
Annual 
Precise Time and Time Interval Systems and Applications Meeting (2017) was published but
unfortunately 
ION publications are not (yet) collected by Library Genesis nor accessible through SciHub so I
cannot 
find a copy. I am not sure I'll find any more technical information there than in the EFTF
proceeding, 
but if anyone can send a copy I'd be grateful.

Thanks, Jean-Michel

--
JM Friedt, FEMTO-ST Time & Frequency, 26 rue de l'Epitaphe, 25000 Besancon, France