In the "good old days" key shaping was done simply by adding a capacitor to the key line or equivalent. That results in an exponential rise and/or fall time, which is not optimum, so the time constant had to be set pretty slow to avoid key clicks. Typically 5-10 ms. 10 ms results in "mushy" keying, especially at high CW speeds.
Raised-cosine key shaping is close to optimum and is easy to implement with a DSP. It allows faster rise/fall times without key clicks. I assume Elecraft is using something like that. Alan N1AL On 2020-06-08 12:51, E.H. Russell wrote: > I'm used to CW rise times in th 4-7ms range. Is this 2.5ms arrived at by a > different metric? Is the curve added by sigmoidal shaping somehow excluded > from the measurement? > > Ed / w2rf > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On > Behalf Of Richard Stutsman > Sent: Monday, June 8, 2020 1:31 PM > To: David Gilbert <ab7e...@gmail.com> > Cc: Elecraft Reflector <Elecraft@mailman.qth.net> > Subject: Re: [Elecraft] CW rise time setting > > Yes, I would regard a 2.5 msec rise time (using appropriate sigmoid > > shaping) to probably be ideal, in which case I would have no desire to > modify or shorten it. I'll bet it will sound even better than a Drake or a > Ten-Tec! > > I hereby withdraw my previous request/opinion. > > Rick N6IET > > On Mon, Jun 8, 2020 at 10:27 AM David Gilbert < <mailto:ab7e...@gmail.com> > ab7e...@gmail.com> wrote: > >> You don't need to generate clicks to have a crisp CW tone. Elecraft > >> uses a pretty much optimally shaped waveform (some version of a cosine > >> function) and if I remember correctly the rise time is only about 2.5 > >> msec, although I could be wrong about that last part. And while you > >> may be careful not to use short rise/fall times when the band is > >> active, in the past there have been folks on the contesting reflector > >> who openly admitted they purposely generate clicks by shortening the > >> rise/fall times to give themselves elbow room. I will always > >> appreciate that Elecraft doesn't give those miscreants the means to > pollute the band. > >> 73, > >> Dave AB7E > >> On Mon, Jun 8, 2020 at 9:23 AM Richard Stutsman < > <mailto:rast...@gmail.com> rast...@gmail.com> wrote: > > I for one would like to have some control over the rise/fall times. > >> You want the cleanest (narrowest) of CW signals when operating on a >> crowded band or in a contest - unless you're a rare DX station. Most >> of my operations are 22wpm rag chews on very uncrowded bands. We're >> often the only discernible signals on an entire CW band. And >> conditions are often noisy with deep QSB. Why not allow those of us >> operating in those circumstances to shorten the rise times a bit, >> which makes it easier to copy in noisy conditions, when any close-in >> clicks or thumps aren't going to bother anybody? Copying a 'soft' >> weak CW signal is like trying to read a 'crisp' signal that's an >> entire S-unit weaker, IMO. > >> My TS-590sg let's me do that, and I love it! > >> Will the K4 sound as good as a Drake T4C? (Just askin'.) > >> Rick N6IET > > N4ZR wrote: > > Will the K4 have options for setting CW rise and fall times...? > Hi Pete, > Probably not. We've always been very careful to ensure our rigs > have an exceptional clean, click-free CW signal. (Third-party > testing bears this > out.) Minimizing the bandwidth requires a very specific rise/fall > time >> and > a hand-crafted sigmoidal shaping function in DSP. > Colonel Sanders closely guards his fried chick recipe, Mrs. Fields > won't reveal what's in her chocolate-chip cookies, and only > selected firmware monks--sworn to secrecy--are privy to Elecraft's > keying envelope coefficients :) 73, Wayne N6KR >> ______________________________________________________________ >> Elecraft mailing list >> Home: <http://mailman.qth.net/mailman/listinfo/elecraft> http://mailman.qth.net/mailman/listinfo/elecraft >> Help: <http://mailman.qth.net/mmfaq.htm> http://mailman.qth.net/mmfaq.htm >> Post: <mailto:Elecraft@mailman.qth.net> mailto:Elecraft@mailman.qth.net > >> This list hosted by: <http://www.qsl.net> http://www.qsl.net Please help support this >> email list: <http://www.qsl.net/donate.html> http://www.qsl.net/donate.html Message delivered to >> <mailto:ab7e...@gmail.com> ab7e...@gmail.com > ______________________________________________________________ Elecraft mailing list Home: <http://mailman.qth.net/mailman/listinfo/elecraft> http://mailman.qth.net/mailman/listinfo/elecraft Help: <http://mailman.qth.net/mmfaq.htm> http://mailman.qth.net/mmfaq.htm Post: <mailto:Elecraft@mailman.qth.net> mailto:Elecraft@mailman.qth.net This list hosted by: <http://www.qsl.net> http://www.qsl.net Please help support this email list: <http://www.qsl.net/donate.html> http://www.qsl.net/donate.html Message delivered to <mailto:e...@qrv.com> e...@qrv.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to a...@elecraft.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
