Hi
….. but why route the key *through* the computer if you are generating
the side tone off of RF…
Bob
On Jul 26, 2013, at 6:16 PM, Brian Alsop <[email protected]> wrote:
Actually computers generate probably 98% of the code during so called
radio contests. During a contest weekend it is not at all unusual for
individuals to make thousands of contacts. Computers automate the
drudgery of sending your call thousands of times and most exchanges.
However even during these contests, the manual key has to sometimes
be used to provide corrections or handle situations not covered by
"canned" messages.
Because of the tremendous adjacent and even on frequency
interference, computers have proved incapable of decoding code with the
accuracy and speed of a human in real time.
Brian
On 7/26/2013 22:04, Bob Camp wrote:
Hi
There's also the time honored approach of generating the side tone
off of the generated RF. In that case the latency to the transmitter
would matter quite a bit. I have no idea *why* you would run the key
through a computer in that case ….
Bob
On Jul 26, 2013, at 4:52 PM, Jim Lux <[email protected]> wrote:
On 7/26/13 12:50 PM, Didier Juges wrote:
There is a difference between managing the latency (as in ensuring
that sound and video are synchronized, but latency itself is
acceptable) and minimizing the latency as in a Morse code keyer where
the operator has to manually control the generation of elements that
can be as narrow as 20mS (one dit at 60 words per minute) while getting
timely aural feedback. That means you need the sound to start and stop
within less than about 5 mS following the key closing and opening.
It is trivial to do on a microcontroller running at 1MHz but
surprisingly harder to do on a 2GHz Windows machine.
It is not just a matter of time stamping the key closure, you have
to get the sound system starting and stopping.
Yep. although, since the propagation path is on the order of 100
milliseconds, providing feedback to the user directly from the
interface works quite well (e.g. generating tones directly from the
keying).
The challenge is trying generate the sidetone through Windows.
But really, there's no reason why you can't have a "keying box" that
provides the direct side tone and sends the events to the host
computer. Then the issue is more about keeping constant latency (or
else the CW will be really, really hard to copy)
It's not like an extra 10 milliseconds of delay between keying and
the emitted RF waveform makes any difference at the other end.
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