Eloran long test from now to August or September.
Interesting observation: The Austron 2100F stays locked even
with all my local noise sources turned on and the LORAN pulse being
obscured (on the scope) by noise pulses.
That is by design.
Back when LORAN-C was designed, the VLF spectrum was considerbly
more crowded by non-random RFI than today.
Although they didnt call it that at the time, the combination of
the GRI, pulse-shape and polarity coding makes LORAN-C a spread-spectrum
signal.
With the exception of badly chosen XX00 GRI's there are literally
no man-made noise sources which survive the de-spreading operation.
The European "NELS" switch to four-digit prime-number GRI's were
made to make it even more robust, unfortunately that also made
European Loran-C robust against any users with existing receivers.
The one minor flaw in the design of the Loran-C signal is that
the master signal pulses are not balanced, so only the slave
signal have the deep null at precisely 100kHz.
See:
http://phk.freebsd.dk/loran-c/theoretical_spectrum/
--
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.
Poul
You just explained something to me on LORAN C. This occurred many years
ago. A fellow out of Italy asked if I could create a system to deal with an
additional delay number for an old Austron 2000 receiver. I had done
something with my 2000. Anyhow I coded up the processor and sent him the
code. But I fear I did not understand NELS. Just maybe the solution was not
correct. Who knows it was a lot of years ago.
No luck last night on the austron 2100F at least the 2100 did go to settle
overnight on Saturday.
Regards
Paul
WB8TSL
On Mon, Sep 18, 2023 at 2:50 AM Poul-Henning Kamp phk@phk.freebsd.dk
wrote:
Interesting observation: The Austron 2100F stays locked even
with all my local noise sources turned on and the LORAN pulse being
obscured (on the scope) by noise pulses.
That is by design.
Back when LORAN-C was designed, the VLF spectrum was considerbly
more crowded by non-random RFI than today.
Although they didnt call it that at the time, the combination of
the GRI, pulse-shape and polarity coding makes LORAN-C a spread-spectrum
signal.
With the exception of badly chosen XX00 GRI's there are literally
no man-made noise sources which survive the de-spreading operation.
The European "NELS" switch to four-digit prime-number GRI's were
made to make it even more robust, unfortunately that also made
European Loran-C robust against any users with existing receivers.
The one minor flaw in the design of the Loran-C signal is that
the master signal pulses are not balanced, so only the slave
signal have the deep null at precisely 100kHz.
See:
http://phk.freebsd.dk/loran-c/theoretical_spectrum/
--
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.
paul swed writes:
You just explained something to me on LORAN C. This occurred many years
ago. A fellow out of Italy asked if I could create a system to deal with an
additional delay number for an old Austron 2000 receiver. I had done
something with my 2000. Anyhow I coded up the processor and sent him the
code. But I fear I did not understand NELS. Just maybe the solution was not
correct.
I hacked something up myself with a PIC16C84 for my 2000, and got it to work-ish,
but then I decided to build my SDR-LORAN-C instead.
Austron did presumably make a 2004 model with an extra divider and thumb-wheel.
--
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.