That experiment is happening, too. Folks will be monitoring WWV and CHU
in narrowband mode with the same tools they use in the frequency
measuring tests. (You can't really do direct phase comparisons on HF
frequencies because between the noise and the ionospheric effects,
including doppler shift, it's really hard to lock to the RF cycle the
way you can at VLF.)
We were originally going to put a 5071A-locked beacon on three ham
bands, but decided WWV and CHU would be better sources, and logistics
were turning into a problem: I'm going to be doing my wideband recording
from a cottage in northern Michigan. But I'm still a time-nut, so the
receiver will be GPSDO-controlled, and there will be a stratum 1 NTP
server in the cottage to provide timestamps. :-)
John
----
On 08/03/2017 03:57 PM, Alan Melia wrote:
A Time Nut would measure phase change across the path of totality using
GPS locked SDR receivers :-)) As was done on the Eclipse that passed
between the UK and Iceland a couple of years ago. Keflavik NRK's
ionospheric signal was returned from inside the path of totality to most
of the north of the UK, giving a good measure of the change in height of
the "apparent reflection height" in the D-layer.
The quoted program looks a bit scattergun......lets record everthing and
see what's there.
Hopefully it will involve a lot of school kids and maybe interest them
in science and electronics. If it does that it will be more useful that
we could imagine.
Alan
G3NYK
----- Original Message ----- From: "John Ackermann N8UR" <j...@febo.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Thursday, August 03, 2017 8:10 PM
Subject: [time-nuts] Fwd: [hpsdr] SDR experiment for the solar eclipse
This is a little off-topic, but thought some of the group might be
interested... so please forgive the interruption.
John
-------- Forwarded Message --------
Subject: [hpsdr] SDR experiment for the solar eclipse
Date: Thu, 3 Aug 2017 15:07:57 -0400
From: John Ackermann N8UR <j...@febo.com>
To: fmt-n...@yahoogroups.com, HPSDR list <hp...@lists.openhpsdr.org>
***** High Performance Software Defined Radio Discussion List *****
I've been working with the "HamSci" group to set up an experiment for
the solar eclipse: wideband recording of several HF bands before,
during, and after the eclipse to look for propagation changes (or
anything else that happens). All are welcome to participate in the
experiment, and this is a *perfect* application for our SDRs!
Here's the HamSci web page:
http://hamsci.org/2017-eclipse-hf-wideband-recording-experiment
Various SDRs and programs have wideband recording capability.
Radios that support the HPSDR "old protocol" (which include
Hermes-based boards as well as the Red Pitaya and possibly others) can
do an even better trick: they can record multiple slices of the HF
band simultaneously, thanks to work by Tom McDermott N5EG.
Hermes can do 4 receivers (tested), Mercury/Metis/Atlas systems should
handle 3 (not tested), and the Red Pitaya can support 6 (tested).
This means that we can record most of the 80M band, and all of 40, 30,
and 20M, in one gulp to look for effects of the eclipse -- frequency
shift, propagation enhancement/reduction, noise floor, etc.
I've written a Gnuradio .grc program that used N5EG's driver to record
multiple receivers. By default it's configured for four receivers on
80/40/30/20M, but that's easy to change. I'll be posting that
software to the TAPR github at https://github.com/TAPR as soon as
we've done a bit more testing.
This software runs on Linux and may work on Windows (I haven't had a
chance to try, but Gnuradio has been ported to Windows). Recording 4
384kHz channels does take some computing horsepower and uses a lot of
disk space -- about 3MB per receiver per second. My prior-generation
i7 machine with solid state drive seems to handle it OK.
If you're interested in participating in this experiment, please (a)
check out the HamSci web page; (b) check the ttps://github.com/TAPR in
a day or two to grab the software and docs; and (c) feel free to
contact me directly with any questions.
73,
John N8UR
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