Paul,
Thanks for great data and analysis.
Comment 1: based on a best-guess loose extrapolation from Davies
(Ionospheric Radio) pp 382-383, the phase slope and total phase shift shown
in your measurements from 00:15 to 07:00 seem roughly consistent with a
March transatlantic path length near 6,000 Km and 29kHz. For such a path
(extrapolating loosely from Davies), the phase characteristic would (very
roughly) be triangular from ~22:00 to ~12:00, with a peak (null) at ~05:00,
which seems to generally fit your measurements. This is a very loose
extrapolation, offered only for any potential value in validating the signal
origin (i.e. not intended to suggest anything regarding accuracy of phase
models).
Comment 2:
My rough guess regarding winter 29MHz diurnal amplitude change would be a
(roughly) 12dB drop in amplitude by full daylight, preceded by some
potentially larger fluctuation or bidirectional fluctuation near sunrise.
For purposes of validating signal origin: a westward non-transatlantic
signal would drop less than 1.2dB by full daylight; a westward transatlantic
signal would drop (roughly) 12dB by full daylight.
Again, the above are rough numbers intended for validation of signal
origin; but even rough diurnal amplitude numbers may be useful in supporting
T/A origin in this case.
Comment 3:
All of the above subject to many variables including details of TX antenna
pattern and modal interference (which are still significant at 5425km)
Thanks Paul and Bob; very interesting evening.
73, Jim AA5BW
-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Paul Nicholson
Sent: Sunday, March 2, 2014 2:33 AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: U.S. VLF License WH2XBA
2014-03-02_06:00:00 0.10 fT 8.3 deg
2014-03-02_06:15:00 0.11 fT 20.2 deg
2014-03-02_06:30:00 0.13 fT 29.4 deg
2014-03-02_06:45:00 0.08 fT 28.4 deg
2014-03-02_07:00:00 0.04 fT 33.9 deg
Phase lead is showing signs of increasing as path
shortens. Expecting the signal level to plummet
now that it is daylight here.
> and *intended* to switch back on at 2330.
If so then the signal was lost in the noise.
> I believe that Bob is at: NL 42-40-05; WL 77-04-28
Thanks, that's 5424.7 km from here, bearing 289.2 deg.
Unfortunately must go out now until about 12:00 UT but the receiver will
continue recording. Will have a closer look at the signal this afternoon.
--
Paul Nicholson
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