[Elecraft] CW rise time setting

Wayne Burdick n6kr at elecraft.com
Mon Jun 8 22:13:27 EDT 2020 

Drew,

We apply exactly the same shape to the sidetone, mute on/off, and mark/space transitions in FSK and PSK modes.

Wayne
N6KR


> On Jun 8, 2020, at 6:54 PM, Drew AF2Z <pubx1 at af2z.net> wrote:
> 
> A little off topic but is the sidetone also shaped or is it just a plain old sine wave?
> 
> Actually, I wouldn't mind having the option to select a sawtooth or squarewave for the sidetone. I'm not sure why but it seems to make sending on a manual key better, prompting the reflexes to be a little crisper maybe...
> 
> 73,
> Drew
> AF2Z
> 
> 
> 
> On 06/08/20 14:38, Wayne Burdick wrote:
>> It’s closer to 4 ms.
>> Wayne
>> N6KR
>> ----
>> elecraft.com
>>> On Jun 8, 2020, at 12:32 PM, E.H. Russell <ehr at qrv.com> wrote:
>>> 
>>> I suppose shaping of the curve corners removes harmonics introduced by the abrupt transitions, allowing an accelerated ramp inbetween. But does this really reduce the total rise time to 2.5ms? It seems that the softening process must take some time. Wish I had a K3 here to scope against other radios. Anything published out there?
>>> 
>>> 
>>> 
>>> Ed / w2rf
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> From: Alan Bloom <n1al at sonic.net>
>>> Sent: Monday, June 8, 2020 3:15 PM
>>> To: E.H. Russell <ehr at qrv.com>
>>> Cc: 'Elecraft Reflector' <Elecraft at mailman.qth.net>
>>> Subject: Re: [Elecraft] CW rise time setting
>>> 
>>> 
>>> 
>>> 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-bounces at mailman.qth.net <mailto:elecraft-bounces at mailman.qth.net>  <elecraft-bounces at mailman.qth.net <mailto:elecraft-bounces at mailman.qth.net> > On
>>> Behalf Of Richard Stutsman
>>> Sent: Monday, June 8, 2020 1:31 PM
>>> To: David Gilbert <ab7echo at gmail.com <mailto:ab7echo at gmail.com> >
>>> Cc: Elecraft Reflector <Elecraft at mailman.qth.net <mailto:Elecraft at 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:ab7echo at gmail.com <mailto:ab7echo at gmail.com> >
>>> ab7echo at gmail.com <mailto:ab7echo at 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:rastuts at gmail.com <mailto:rastuts at gmail.com> > rastuts at gmail.com <mailto:rastuts at 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
>>> 
>>> 
>>> 
>>> 
>>> 
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