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 <jim...@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. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
