Dear LF Group,
Thanks for the reports on the 73k Beacon last night. It would appear that
Laurie's extra few dB of ERP makes all the difference, and also that QSB is
something of a limiting factor with very long dot lengths, as was the case
with 136k last winter.
Running the 73k TX in Wolf mode should be OK; I have not done it before,
but all the necessary circuitry is in place. I am not sure how effective it
would be - earlier in the year I compared Wolf to QRSS by adding white
noise to locally generated signals and comparing the SNR required to
produce usable signals with each mode. The result of this was that Wolf
worked at signal levels that would produce readable QRSS with 30 - 60
second dots. At this level, the advantage was with Wolf in that it is much
quicker than QRSS30, however there is a fairly sharp threshold between Wolf
producing perfect copy and no copy at all. So I suspect that, in it's
current form, Wolf would not be able to produce any copy with the signals
I can achieve on 73k. However, there are many variables, and if people are
interested, I could try running a Wolf beacon on 73k. I would need to know
what frequency would be suitable - the bandwidth of the BPSK signal is much
wider than QRSS of course, and so a reasonably clear 40Hz or so would have
to be identified on the western side of the pond before making a realistic
attempt.
I like VE1ZJ's idea of simultaneous 73k and 136k tests - So I think I will
try a 136kHz beacon tonight, assuming Laurie and/or Peter can be QRV on 73k
this evening, hopefully we can take advantage of the current fairly good
conditions. I will try 135.923kHz, QRSS30 with approx 1W ERP, from about
2230 onwards, unless anyone has a better idea.
Cheers, Jim Moritz
73 de M0BMU
|
