Mon Dec 15, 2014 9:57 pm (PST) . Posted by:
Hardly natural radio, but a good test of a VLF receiver.Wolf's vlf6 has been picking up an amateur transmission
by W4DEX at around 9kHz from 35.27N,80.37E which is a new distance record for amateur VLF signals: 6918 km.
Thanks to the streamed signal and the recording 'loop' onthe stream server, it is quite easy to analyse the timestamped signal to tease out these ultra weak signals.
The signal strength at Bielefeld is equivalent to about4 extra electrons on the E-field probe.
It is interesting that the vorbis compression used by the uplink to the server does not noticeably degrade the S/N ratio of weak signals buried in the noise.
W4DEX is only about 250km from Mike Smith's receiver at Forest VA, which picks up the signal very well indeed.
Spectrogram from vlf35 from a recent transmission
For comparison this is how an amateur VLF receiver picks up
W4DEX at a range of 210km,
which shows well how good Mike's natural radio receiver is.
I think at the moment, Kevin's receiver at Hawley holds the
USA distance record for over-land reception.