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Attempting to resend...
Sent: Saturday, October 04, 2014 1:18 AM
Subject: Re: LF: ZEVS RX ant question, now success - 60 Hz in
Europe
Hi Wolf, Stefan,
yes I also noticed a weak 60 Hz line during my ELF
experiment, and it is there in the accelerated wav files. Here are two
spectrograms with 15.3 mHz bin width:
Unlike Zevs, 60 Hz seems to be more pronounced
during 1855-2055 UT recording, ie our evening when the Atlantic was still in
daylight. It was hardly visible in the morning, 0541-0741 UT.
During the two evening hours, the 60 hz line
drifted up and down by about two pixels, 30 mHz. That frequency instability
may actually be a unique signature which can be used to exclude local origin,
simply by comparing simultaneous traces from two different receive
sites. I think there may even be an online log of American line
frequency history, but couldn't find it on the web - any hints from
the group?
Best 73,
Markus (DF6NM)
Sent: Saturday, October 04, 2014 12:41 AM
Subject: Re: LF: ZEVS RX ant question, now success
Hi Stefan and all,
you wrote:
Yes, a
good idea. I will try to catch it :-) But how do i know that it is the US mains
instead of a 60 Hz monitor? Is the 60 Hz from the mains more stable?
I
guess the opposite: Similar to our Eu mains frequency, the US 60 Hz signal
"wanders around" very slowly, as the load changes, but in the long run they also
keep the frequency stable, nation-wide. Not sure about the maximum excursion
from the nominal frequency (I lost the notes and screenshots years ago when a
harddisk died) and how many mHz per minute the frequency may drift. But you can
see the weak 60 Hz trace in Renato Romero's ZEVS spectrogram at
http://www.vlf.it/zevs/zevs.htm
73,
Wolf .
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