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LF: The 137MHz RTTY station

To: "rsgb_lf_group" <[email protected]>
Subject: LF: The 137MHz RTTY station
From: "Alan Melia" <[email protected]>
Date: Sat, 12 Jun 1999 23:26:41 +0100
Reply-to: [email protected]
Sender: <[email protected]>
I left my receiver running into FFTDSP4 at Friday midnight, with the longterm monitor storage enabled (by about 1000Z on Saturday it had accumulated a 24 meg file) The 137.0 RTTY signal was not apparent when I went to bed at about 2330Z. It appeared on the screen at about 0015Z and was quite strong between 0100Z and 0330Z with a peak in strength at about 0300Z. During this part of the night (well morning I suppose) there was a steady background 'crackle' like distant storm activity. At its strongest it was reading 20dB S/N on FFTDSP's 'measuement'. This is about the same as I see for the strongest G stations in good conditions. There is a noticable decline to 0330Z with a marked reduction in the background noise. By 0340Z it was down to 10dB S/N and by 0400 it had totally disappeared from the screen to background noise virtually disappeared at the same time. An interesting point was that the signal faded into the noise for several minutes then rose out of the noise again for about 5 minutes and then faded away all together. This reminds me of the way I have heard the HF bands close to DX when I used to be more active up there. I have not yet investigated the Grey-line for 10th/11th June but I suspect that this may explain why we are not hearing the Halifax N.S. (??) station as much as we used to earlier in the year. (just for identification purposes I make the shift about 75-80Hz  in the 2Hz resolution mode of FFTDSP)
Unfortunately I am unable to log signal strength as only the lightning crashes move the s-meter using my passive loop. As an indication of my sensitivity, I could see DF2PY (136.9 kHz) on my screen on Sat morning at about 6dB S/N but I could not copy his morse. I know it was him from the Cluster spot he put up and I think PA0LQ worked him later.
General activity seemed to start about 0515Z, with the first qso I observed at about  0524Z.
 
In conclusion this observation would suggest that the best time for Transatlantic QSOs would be about half an hour before dawn ( I dont know whether that is the visible dawn or a sort of 'radio' dawn) It looks like we will need some insomniacs to work the States.
I understand the AMRAD beacon is operating now.....is it on 136.75?? as was projected.
I will try to set up some signal strength logging, but also calibrate the sensitivity of my loop aerial.
Hope that was interesting
Cheers de Alan G3NYK
 
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