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Thanks to all who responded to this unusual news.
Unlike other some other stories told today, this one is completely
true!
It was triggered by the beautiful description of
the oscillator on
www.leapsecond.com/museum/earth
However
the frequency given there is slightly incorrect, as it was calculated from a 24
h solar day, instead of the slightly shorter rotation period in an inertial
system.
The electromagnetic signal is caused by the earth's
magnetic dipole moment (8e22 Am^2) rotating around the N-S axis at an 11 degree
tilt angle. The radiation power from the rotating component can be calculated
as
2 * 0.5 * 31171 ohm * (8e22 Am^2 * sin(11°) )^2 / lambda^4 = 16
µW,
with the first factor of 2 for the "turnstile" configuration, equivalent
to two loops fed in quadrature.
A report from the far field (1 lightday / 2pi)
would certainly be good news for the SETI community ;-)
Congratulations to Jim for uncovering the Doppler
modulation caused by annual motion of earth, an effect which I hadn't thought
of. Depending on the position of an observer relative to the ecliptic, the 31.7
nHz sidebands due to this "Moritz effect" could be up to -35 dBc, which should
be quite noticable ;-)
Happy springtime to all in the group,
Markus (DF6NM).
Sent: Sunday, April 01, 2012 8:28 AM
Subject: ULF: 11.6 µHz transmission
Dear LF,
in a joint project including a number of radio amateurs, our group is
working on a large experimental earth-antenna system, which is able to radiate
an ultra-low frequency signal at low power.
We are currently transmitting an unmodulated test carrier on 11.60576 µHz,
and (according to our measurements) are achieving a radiated power of 16
microwatts. Frequency stability is on the order of 1e-8, which should enable
narrow bandwidth observations with high sensitivity.
The transmission has been on air for a while. Any reception reports
(especially of far-field detections) would be much appreciated.
Best 73,
Markus (DF6NM)
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