On Nov 20, 2013, at 3:01 PM, Kai wrote:
> I think that discussion should center around what the BW limit [should] be
> for digital signals. The answer will likely be something between 2200 Hz and
> 2800 Hz, because signals as wide as 2200 Hz are already permitted. It's good
> to discuss this.
For conversational (keyboard, human-to-human) digital modes, 300 Hz to 500 Hz
is ample, and wide enough to use statistical detection methods that take
advantage of the frequency diversity aspects of selective fading on the HF
bands.
300 Hz is also sufficient to do weak signal experiments to your heart's content.
The only reason anything wider is needed is to transmit massive amounts of
"data" or digital voice.
Unless there is some enforceable rule that controls mutual interference between
conversational mode users and data mode users, the proposed change by the ARRL
only opens all of us to even worse QRM. Even a 1 kHz signal in the midst of an
RTTY contest or pileup can completely ruin it. That is what is so wrong with
the ARRL proposal.
73
Chen, W7AY
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