Attempting to resend...

 

From: Markus Vester

Sent: Saturday, October 04, 2014 1:18 AM

To: [email protected]

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:

http://df6nm.bplaced.net/VLF/ELF/elf_140903_1855-2055_60Hz_82Hz.png

http://df6nm.bplaced.net/VLF/ELF/elf_140904_0541-0741_60Hz_82Hz.png

 

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)

 

From: wolf_dl4yhf

Sent: Saturday, October 04, 2014 12:41 AM

To: [email protected]

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 .