Re: LF: VLF dj8wx on 8970.022Hz

[Roger Lapthorn <rogerlapthorn@gmail.com>]

Hi Stefan,

I enclose here the full wider band 3 day plot of the noise (and mystery signal) as received in 424uHz BW here in JO02dg near Cambridge. Do you have any comments please? The mystery signal appears on all three nights at 8.9701kHz. It looks like a little "hook" shape over about 4 hours.

BTW, the loop/preamp system is receiving the alpha beacons very well, typically 20dB over the noise. See http://www.youtube.com/watch?v=TDxRhQYg7lQ for a video showing alpha beacon reception using the SM6LKM software VLF receiver.

If the interference/noise at 8.9701kHz was natural then surely it would be amazing for such signals to exactly repeat 3 nights running at exactly the same frequency? OK, I agree the general background noise floor may be partly man made and partly the natural noise floor changing diurnally but the oddity at 8.9701kHz?

The grabber is currently OFF as I shall be away for a couple of days, but still in email contact.

73s
Roger G3XBM

2011/3/9 Stefan Schäfer <Stefan.Schaefer@iup.uni-heidelberg.de>

Hello Roger,
Am 08.03.2011 20:51, schrieb Roger Lapthorn:

Nothing visible on my grabber https://dl.dropbox.com/u/15047843/xbm_grab.jpg yet this evening but I have a high noise level in the evening hours from lights, TVs etc.Leave the TX running overnight please as I hope to see your signal after midnight and through tomorrow morning. In the 423uHz bandwidth and with the slow scroll speed it will be more difficult to see than when you were sending a continuous carrier a few days ago.

Are you sure it is local QRM? Maybe its just the usual QRN that risies strongly in the evening. It is as strong as never before within this year now :-( And things will get even worse. We have to make QRO, faster than nature does it ;-)

To check the local QRN/QRM situation it would be helpful (and interesting!) to have a wideband screen from you. If you want, you could run a second SL instance simultaneously and upload the pictures. You know how the wideband windows looks, from grabbers like TF3HZ which is most interesting each day :-)

Also you may arrange a real website and store it on your dropbox. There you can include several pictures in one link, the link to the website :-)

Best 73, Stefan/DK7FC

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424uHz_8970_march7to9_2011s.jpg
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