From: <hvanesce@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
References: <5489EFBC.3050401@abelian.org> <5489F474.4030904@abelian.org> <5489FA44.3010709@abelian.org> <548AA644.4030707@abelian.org>
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Date: Fri, 12 Dec 2014 10:17:42 -0500
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Subject: RE: VLF: 8819.9 Hz in Virginia?
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Paul,

I've been monitoring near 8820 since Dex's prior transmission (assessing and
mitigating noise in case Dex switches on again). I don't have good
absolute-frequency calibration at this northern Virginia location, and I'm
interested in whether the signal captured at Forest (near 8819.9) is the
same signal that I have seen almost continuously for the past 6 days (I have
seen occasional small frequency shifts that do not seem like utility power
line frequency shifts). I tried to correlate the ~0.01Hz delta-f feature
shown in your spectrogram link (below), between 1400 UTC and 1700 UTC, with
my local spectrogram. This raised a Spectrum Lab question: my spectrogram
data was captured at ~ 1mHz resolution (715 uHz bin width), and accordingly
I can't quite discern 0.01uHz features (like the one shown in your Forest
link) in my waterfall display. Can I inspect previously captured Spectrum
Lab data at higher resolution by accessing a data file, or perhaps by
opening a new waterfall-display window? Apologies for bothering you with
this detail-level question; I wanted to try to correlate my data with the
data in your link below while the data is still in my Spectrum Lab buffer,
and without corrupting or erasing the data in the attempt to inspect it at
higher resolution. 

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: Friday, December 12, 2014 3:25 AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: VLF: 8819.9 Hz in Virginia?

Spectrogram covering 24 hours yesterday

  http://abelian.org/vlf/tmp/141211c.gif

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
--