Paul,
In small VLF horizontal TX antenna simulations (NEC and FEKO) I have noticed
that comparatively small inclinations (10 to 15 degrees) from horizontal can in
some cases make a substantial difference (5 to 10dB) in far-field signal
strength. Not sure how real those NEC/FEKO simulation results are,
notwithstanding best efforts on ground parameters and ground model. I guessed
that your LWPC simulation of Stefan's 5170 Hz antenna had the LWPC TX antenna
inclination parameter set for horizontal; and with the experimental and model
results so consistent I couldn’t resist asking.
Nice to see history in the making with the 5170 Hz tests; well done all.
Speaking of LWPC and hopes/reservations thereof: the (safe) link below provides
free download of an interesting first-pass on a new type of LWPC
amplitude/phase model for flares/SIDs:
http://www.ann-geophys.net/31/765/2013/
The flare-induced amplitude/phase characteristics in the above model differ
somewhat from observations made in:
https://arxiv.org/abs/1603.07300
but both papers have some interesting new perspectives
73,
Jim AA5BW
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Paul Nicholson
Sent: Tuesday, January 3, 2017 3:07 AM
To: [email protected]
Subject: Re: VLF: Back on 5.17 kHz / 58 km...
Stefan wrote:
> f = 5170.000000 Hz
> Start time: 02.Jan.2017 17:00:00 UTC
> Symbol length: 40 s
> Characters: 5
> CRC 16
> Coding 16K25A
Received 'HELLO', BER 41.1%, constant reference phase.
Carrier Eb/N0 = +1.0 dB, S/N: 15.57 dB in 22.3 uHz,
A little weaker than expected.
S/N -64.9dB in 2.5kHz after sferic blanking. Before the blanker, the signal
measures -74.8dB after hum removal.
Markus wrote:
> SpecLab resets the phase of it's GPS-locked signal > generators at midnight.
Ah, that would explain it, thanks. Now you mention it, I think we've hit that
problem before but I had forgotten.
I measure a phase advance of 131 degrees at midnight.
We had better stick to frequencies that are a whole number of
cycles per day. That also simplifies coherent stacking of
daily transmissions.
Jim wrote:
> Was the LWPC TX antenna angle parameter fairly close to > actual angle?
I'm not sure what you mean there.
--
Paul Nicholson
--
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