Tom, "on point" ....... I am, almost exclusively, a CW and Digi op in that
order. I will say, anecdotally, that I have not experienced any
interference caused by one or the other to the other on 160. I admit that
I am not THE most active op on 160, but I am there a fair amount of time.
Every experience will be different because of geographical location, antenna
and equipment, noise floor, and operating habits.
Proper frequency planning requires understanding potential problems and how
to handle them, not pretending if everything works perfectly and appears OK
at the moment, it will always be OK.
Again, a good thing to consider is Collins. They assumed running a clean
audio tone into the audio of SSB transceivers and transmitters was a good
way to generate CW, and a good system to release into the field.
They must have assumed carriers were always balanced, there was never
harmonic distortion, and there was never hum or noise. They probably assumed
equipment would always perform like new, and always be properly operated.
They got bit pretty hard by that. The lesson from that should have been
audio injection of tones produces a limited signal-to-distortion ratio and
is subject to equipment and operator malfunction.
If It goes in the front of a SSB bandwidth system, it should be treated as
SSB bandwidth for distortion products.
Yaesu, for a more recent example, generated an almost square rise and fall
waveform CW signal and processed it through a SSB system as a CW signal. The
filter BW used was a few kHz. If they didn't waveshape properly later in the
system, they should have ran it through a CW filter.
There is also a problem with NDB harmonics on 160. This is another case of
poorly engineered systems that depend on perfect linearity to prevent
interference. For all who think low level modulation followed by linear
stages is a good system to prevent spurious, we can find many examples where
that assumption caused problems. I can hear some 5th and 7th harmonics from
25-50 watt NDB transmitters from over 1000 miles away, and getting them
fixed is like telling a digimode guy he has an issue with spurious.
This isn't a new, or unheard of, engineering problem. I would think Hams in
particular would be more in tune with proper planning that considers less
than perfect systems.
Since most 160 band plans, like the DX window, seem to have gone by the
wayside, it would be incumbent upon us as those who love the band, to come
up with one that includes the newer modes. The reason? Better
utilization by those who have WAY LESS than optimal stations for 160.
The real concern I have is growth in popularity of multiple modes that all
go into a SSB transmitter audio channel, and that are all dependent on
virtually no distortion or noise to maintain modest quality.
An example I would use for this is PSK31, where many users almost lynch
other users who run more than a barely discernable signal. While the blame
is placed on amplifiers, the root problem is very limited dynamic range of
the system. Because it is so difficult to keep distortion and spurious TX
levels down, and because receivers often pass much more BW than the desired
signal, they decided to make everyone stay somewhat close to noise floor.
Like a used car dealer would do, limited dynamic range is presented as a
"feature". Saying "No one needs power or good antennas because the mode is
so efficient" is a good way to mask issues caused by amplitude changes in an
audio tone driving a SSB transmitter, and using a wide SSB channel in a
receiver of a narrow band signal.
You won't find many CW operators who think 2.7 kHz IF filters followed by a
31 Hz wide audio filter is a good system for dynamic range.
As audio into SSB transmitters and back through SSB receiver modes become
more popular, it will be tougher to keep a *lid on shortfalls*. There also
won't be a *shortfall of lids* (intended as a pun) who mis-adjust things, or
wire things wrong.
Ask yourself this...
If digimodes get more and more popular, where will they expand if we start
them smack in the middle of what was a weak signal area? Does anyone here
really think the best place to have started digital modes was in the middle
of the most popular DX weak signal area?
Or are we really just pretending 1835-40 was a good idea, and there will
never be more than 30 operators using digital modes, all QRP, and all with
perfectly adjusted radios?
73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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