This is most interesting. I wonder if they do this sort of thing
often, for maintenance perhaps. At 25dB down they are pretty much
below the noise floor here. I use a Wndel&Golterman SLM,
modified to provide audio output, to listen to the various stations,
and a 96kHz USB soundcard and Spectrum laboratory to see the
spectrum from DC to 48kHz. The Alpha stations normally are all well
above the noise level day and night.
Also interesting to see that some of the stations I see over here
are visible on the other side of the world. Now if only I could also
see the amateur stations.......
73
Con
On 27/10/2010 6:15 a.m., Stefan Schäfer wrote:
It seems the Alpha TX at 11904 Hz is/are not
completely OFF but rather about 25 dB weaker in the moment! I
still receive a signal, 20 dB above noise in 176 µHz here...
73, Stefan
Am 26.10.2010 13:40, schrieb Stefan Schäfer:
Hello Con,
Thank you!
The Alphas are currently off.
You can check it on my VLF grabber if you want, it is running
24/7:
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html
There is a grabber window (RSDN-20_F1) which shows the Alpha
trace at 11904.7619 Hz. You can see it is OFF since 2 days. The
lower window (wideband) shows the VLF spectrum, as received here
in Heidelberg. There, you can see all 3 Alpha traces, if they
are ON, at about 15 dB S/N, depending on daytime but always
visible...
Good luck in experimenting down there :-)
73, Stefan/DK7FC
Am 26.10.2010 11:29, schrieb ZL2AFP:
Hello folks,
I am new to the group and have been following with great
interest the VLF experiments. Congratulations to Stefan on
such great DX (1000+km). This is really good stuff.
I have noticed in recent days that the Alpha stations at 11.9
and 14.8kHz seem to have stopped transmitting. I can normally
hear seven stations but they have all disappeared. So I am
wondering if propagation has taken a dive, or perhaps the
stations have gone QRT?
Has anyone over there heard the Alpha stations recently?
73
Con ZL2AFP
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