In theory, there really is no difference. The math is equivalent and
there's no way you can distinguish a CW signal that starts life as a
keyed AF tone and gets mixed up to RF and one that starts as "RF" or
some intermediate frequency oscillator.
In practice, it may be a different story. Your code practice
oscillator and AF chain can be noisy and distorted, even if there are
no dogs barking or phones ringing. The DSP rigs probably generate the
waveform mathematically and noiselessly -- except for sampling and
quantization issues. (Some filtering is required to purify the output
of any digital-to-analog converter, and that might add some extra
"personality".) I'd expect them to be pretty close to ideal -- and a
lot better than some non-digital rigs you can still hear on the air.
73, Martin AA6E
On 4/24/05, Bob Stephens <bstephens1@mindspring.com> wrote:
...
> 5. I still don't really understand what J2A audio type keying is. What is
> the difference between J2A and simply keying the rig in SSB mode while
> holding the microphone to the output of a code practice oscillator?
>
> It is possible that I'm totally clueless <grin> ... and so I ask questions ;-)
>
> tnx & 73
> Bob, KB1CIW
>
--
martin.ewing@gmail.com
http://blog.aa6e.net
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