Von: Roger Lapthorn <[email protected]>
Gesendet: 05.06.2010 21:49:29
An: [email protected]
Betreff: LF: 1.5kHz earth-mode update
Attached is a map showing the coverage around the village using 4W TX to a 20m baseline earth electrode pair receiving on an 80cm 30t loop.
Green dots show signal received
Orange dots show signal just copied (limit of range)
Red dots show no signal copied (either too weak or buried under 50Hz fog)
As mentioned yesterday, I tried to receive the signal (by ear only at this stage) at various places around the TX out to about 0.8km but maximum range across open fields was 0.5km. In the village itself coverage was solid due to conduction of the signal through metal water pipes out to about 0.25km in most directions. Across the open fields reception was by pure induction judging by the loop direction. At some test points the signal was buried in 50Hz "fog" despite quite good active high pass filtering and copy was impossible.
These results do suggest that this TX/RX system is capable of greater than 1km despite the 4W low power if using QRSS and a PC receiver. This I shall confirm after my grandson goes back home to London in about 7 days's time and I get my shack back. Further distances will then depend on more power, better electrode spacings, possibly a large loop at the TX end, or even a Marconi antenna as the German stations have been trying.
Despite Mal's concerns there is now a "head of momentum" building in sub-9kHz experimentation, whether looking for super-DX by true radiation or more limited testing by induction and conduction. It is all fascinating stuff and quite possible to do with very modest test equipment and gear.
73s
Roger G3XBM
--
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