On Tue,2/23/2016 1:26 AM, Paul O'Kane wrote:
That is normal. Any station 60db above the noise appears,
and is, wider at the noise floor than one that is 6db above
the noise. If the stations have similar levels of clicks,
those from the first station will be 54db stronger - and
54db more irritating.
"Wider at the noise floor" is a dumb way to define occupied bandwidth.
But the view on the spectrum display DOES show the effect of a station
with strong clicks or phase noise on an adjacent station trying to copy
a weaker one. Consider a station running 1,5kW into antenna with 7 dB
gain pointed at you. That's 7,5 kW. 40 dB down from that is 0.75W ON
YOUR FREQUENCY! 30 dB down is 7.5W. I ran 5W this weekend and made about
200 EU QSOs.
The louder your station is, the more occupied bandwidth matters. I live
5 miles from K6XX who runs k3s with tube amps that he carefully tunes,
and about 15 miles from another station who uses a 7600 with several
different amps. I also run K3s with well tuned tube amps. All three of
us are running 1,5 kW. K6XX and I can run 500 Hz apart on CW and barely
know the other is there. That other station with the 7600 burns nearly
10 kHz.
Jukka is a member of the CQ WW Contest Committee. I have
suggested to this committee that a way to deal with clicks
would be to define "excessive bandwidth" in terms of width
at 30db or 40db down - easily measured on a P3 or similar.
This is an excellent suggestion, but I would suggest that the number be
AT LEAST 40 dB down for the reasons noted above. 50 dB would be even
better, but is far more difficult to measure under crowded band conditions.
The committee could take the lead on this issue, if it so
wished. Signal widths could be verified with the committee's
SDR recordings.
The committee SHOULD take the lead on this issue. Randy and the
committee have done contesting a major service by taking action against
flagrant cheating, and I think we all hope that work will continue.
Signal cleanliness is the next big issue, and should definitely be
attacked head on. I've made some contributions in the form of
k9yc.com/TXNoise.pdf and measurements displayed in a Power Point
format http://k9yc.com/P3_Spectrum_Measurements.pdf
Education is also a major part of the solution. Contesters need to
understand that fast rise times CAUSE clicks, that some rigs are FAR
cleaner than others, and that power amps that are poorly tuned, or
overdriven, or that use AGC to set TX power, ALL cause clicks. Also,
some amps that use "automatic bias" also cause clicks. I've recently
written a piece for NCJ that will run in the issue that mails next month
that addresses this issue for SSB, and the discussion of the
contribution of power amps to the problem applies directly to CW.
73, Jim K9YC
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