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Hi Jim,
>my spectrogram data was captured at ~ 1mHz
resolution (715 uHz bin width),
Your resolution is actually similar enough to
Paul's 833 uHz bins, and the excursion on the unid signal (around 0.010 Hz,
not uHz) would be clearly visible. Could you post your spectrogram around 16 UT
yesterday?
Best 73,
Markus
Sent: Friday, December 12, 2014 4:17
PM
Subject: RE: VLF: 8819.9 Hz in
Virginia?
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: [email protected][mailto:[email protected]] On Behalf Of Paul
Nicholson
Sent: Friday, December 12, 2014 3:25 AM
To: [email protected]Subject: Re: VLF: 8819.9 Hz in Virginia?
Spectrogram covering
24 hours yesterday
http://abelian.org/vlf/tmp/141211c.gifA 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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