JF
jeanmichel.friedt@femto-st.fr
Tue, Aug 5, 2025 11:47 AM
Thank you for all the replies.
If it can be of any interest to others, I have started
https://github.com/jmfriedt/kiwisdr_timetransfer/
to address the various VLF time transfer signals I am familiar with,
ideally recorded from a same location.
ALS162 and DCF77 are easy enough but just to make sure reading the KiwiSDR
IQ records and GNSS timestamps is achieved correctly (and an opportunity to
see sunrise/sunset on DCF77). LORAN is new to me so I am struggling with
the GRI not leading to an integer number of code copies in each second: I
have seen that there is a Z counter providing the code index within each hour,
but have not decoded this information and am at the moment relying
instead on the GNSS timestamp to identify the code position. I have
read that one improvement of eLORAN is to disseminate a UTC timestamp
message, probably making time transfer somewhat easier than what
I am experiencing at the moment. The +/-1 us PPM should be seen as a
+/-36 degree phase shift I expect, still detectable even at the rather
slow sampling rate of 12 kS/s provided by the Kiwis. Still work in progress...
Thanks, Jean-Michel
--
JM Friedt, FEMTO-ST Time & Frequency, 26 rue de l'Epitaphe, 25000 Besancon, France
August 3, 2025 2:43 PM, "Poul-Henning Kamp via time-nuts" time-nuts@lists.febo.com wrote:
Poul-Henning Kamp writes:
The snapshot attached show the I+Q plot of that modulation, without
the eLORAN modulation, the dots would form a straight line.
forgot the picture...
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Thank you for all the replies.
If it can be of any interest to others, I have started
https://github.com/jmfriedt/kiwisdr_timetransfer/
to address the various VLF time transfer signals I am familiar with,
ideally recorded from a same location.
ALS162 and DCF77 are easy enough but just to make sure reading the KiwiSDR
IQ records and GNSS timestamps is achieved correctly (and an opportunity to
see sunrise/sunset on DCF77). LORAN is new to me so I am struggling with
the GRI not leading to an integer number of code copies in each second: I
have seen that there is a Z counter providing the code index within each hour,
but have not decoded this information and am at the moment relying
instead on the GNSS timestamp to identify the code position. I have
read that one improvement of eLORAN is to disseminate a UTC timestamp
message, probably making time transfer somewhat easier than what
I am experiencing at the moment. The +/-1 us PPM should be seen as a
+/-36 degree phase shift I expect, still detectable even at the rather
slow sampling rate of 12 kS/s provided by the Kiwis. Still work in progress...
Thanks, Jean-Michel
--
JM Friedt, FEMTO-ST Time & Frequency, 26 rue de l'Epitaphe, 25000 Besancon, France
August 3, 2025 2:43 PM, "Poul-Henning Kamp via time-nuts" <time-nuts@lists.febo.com> wrote:
> --------
> Poul-Henning Kamp writes:
>
>> The snapshot attached show the I+Q plot of that modulation, without
>> the eLORAN modulation, the dots would form a straight line.
>
> forgot the picture...
>
> --
> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG | TCP/IP since RFC 956
> FreeBSD committer | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe send an email to time-nuts-leave@lists.febo.com
