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Re: VLF: 8819.9 Hz in Virginia?

To: <[email protected]>
Subject: Re: VLF: 8819.9 Hz in Virginia?
From: "Markus Vester" <[email protected]>
Date: Fri, 12 Dec 2014 09:47:12 +0100
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Hmm 8820 Hz is a 60 Hz multiple, so maybe not the best choice for American observers. On the other hand, the trace at Forest seems to be too stable for a direct mains harmonic.
What I often see here both at VLF and LF are crystal controlled carriers, accompannied by sidelines at 16.7 or 50 Hz multiples, presumably from railway power converters which are driven by a microcontroller.
Best 73,

Sent: Friday, December 12, 2014 9:24 AM
Subject: Re: VLF: 8819.9 Hz in Virginia?

Spectrogram covering 24 hours yesterday

A wandering signal from a crystal source of average stability.
These are fairly common when you dig deep enough into the noise.
Fortunately easy to distinguish from a GPS locked amateur signal.

Demonstrates how useless an undisciplined xtal osc is for VLF
(tx and rx).

Paul Nicholson

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