[time-nuts] RS 232

[Didier Juges]

There are a number of things that can be done to go around Windows latency, but just like Time-Nuts are not satisfied with a just adequate timing solution, some hams don't like having an extra box if it can be avoided. When you take your rig and equipment to a far away destination, the most you can do with the minimum number of boxes, the better off you are.

Personally, I made my own keyer with an 8051 just because it was more fun than buying one, and I don't want to spend the time to go around Windows idiosyncrasies, but to each his own.

Didier KO4BB


Bob Camp <lists at rtty.us> 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 <jimlux at earthlink.net> 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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