Dear Andy, LF group,
Thanks for the tests - I received the G4JNT Jason beacon last night for a
few hours. With a loop antenna aligned on Andy's QTH , the signal started
off as "nearly audible", and strong enough to produce full quieting on the
Jason waterfall display. So as a crude test of low SNR conditions, I turned
the loop until the signal was almost nulled out, and copy was marginal.
Under these conditions I found the KK7KA decoder produced consistently
fewer errors, corresponding to an advantage of a few dB, I suppose. I found
that a signal that would be "M" copy viewed as 10s/dot QRSS would give
almost perfect copy (a few % of corrupt characters) using Jason with the
KK7KA decoder. I also found that my old P133 computer gave results
consistently a few dB better than my newer laptop - this was true both with
Jason and with the Spectrum Lab waterfall display, so would seem to be due
to the different sound card hardware rather than any software issue; worth
investigating further. As it got dark, the noise level rose by about 20dB,
so by the end of the session, I had to gradually turn the loop so it was
lined up with G4JNT again to get good copy.
Cheers, Jim Moritz
73 de M0BMU
At 08:27 07/08/2002 +0100, you wrote:
I will be transmitting another Jason test transmission at low power tonight
137.500000 kHz < 500uW ERP. Start time at least by 1900z, and probably
earlier.
Andy G4JNT
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