From: <hvanesce@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
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Date: Sun, 23 Apr 2017 06:34:07 -0400
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Subject: RE: VLF: Some natural signals
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Thanks Paul,

What a wonderful sound.

Unfortunate that bird's magnetic sensors don’t have the sensitivity/bandwidth for what you captured; they could perhaps tune their nav systems for reduced sensitivity to the disturbance that chorus indicates.

Do you know if anyone has made audio translations of the mHz to 1Hz ionospheric-TEC waves (which modulate signals in HF and other bands)?  I'm referring to what some folks call ULF waves, where ULF refers to a geophysical-community convention of roughly 1 mHz to 1 Hz.

Or if anyone has made audio translations of the mHz to Hz modulation that magnetic storms can impress on VLF signals?

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, April 23, 2017 5:31 AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: VLF: Some natural signals


 > Is that recorded with antenna direct into soundcard  > (metaphorically speaking ) ?

Yes.  There's no frequency shift, just amplification of the audio frequencies present on the E-field probe.

Not even that much amplification, on the order of x50 voltage gain before the soundcard (which needs 4 volts for full scale).
The only post processing is hum notching, 5 pole high pass at 300 Hz and 3 pole low pass at 10kHz.

--
Paul Nicholson
--