Paul,
Thank you for the excellent data and processing, and the inspiring results!
Bob, thank you for your TX work and excellent signal!
I should leave well enough alone but:
The nominal (which never happens) night-to-day increase in attenuation over
this path may be around 14dB in early March. By midsummer, night-to-day
increase in attenuation might nominally be 35dB. Paul's optimized
spectrograms (below) show (~13dB?) SNR. If the nominal numbers are somewhere
close to reality, this could be a window of opportunity for demonstration of
24-hour TA capture. Since the daytime window for this path is gradually
closing (0.2dB per day if processes were linear, which they're not), I
thought I'd mention it. Easy for me, I don't need to hold the corona-spray
can round the clock.
73, Jim AA5BW
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Paul Nicholson
Sent: Monday, March 3, 2014 11:18 AM
To: [email protected]
Subject: Re: LF: 29.499 QRSS 180 for remainer of night...
I made a spectrogram of the Morse transmission using a transform width equal
to the 180 second dot length, advancing the transform by 60 seconds each
time
http://abelian.org/vlf/tmp/29499_140303_180_60_rect.png
As expected, the signal is now 'in the yellow'.
Markus advised me that using a shorter transform aids readability
even though it discards some S/N. Here it is with 90 second
transform advancing by 45 seconds,
http://abelian.org/vlf/tmp/29499_140303_90_45_rect.png
and sure enough it is now quite easy to read the Morse letters.
There is one 'B' where the dash is broken into two dots by a noise spike.
I tried Hann and some other windows but rectangular seemed to do best.
The 10mHz shift was very effective and ought to ID the signal
even if the trace was very faint on a spectrogram. Fingers
crossed for some reports from further into Europe.
The signal was showing no sign of fading out by 08:00 UT so I guess it would
still come through for another hour or maybe two.
--
Paul Nicholson
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