If, using an ole timey receiver with no DSP stuff, I notch out the audio
note of the received CW signal, I can then better hear all sorts of
artifacts if they are there. Often I can hear the artifacts greatly
accentuated when selective fading reduces the main signal.
73, Mike N4NT
----- Original Message -----
From: "Alderman, Chester" <CAlderma@ora.fda.gov>
To: "'Steve Ellington'" <N4LQ@igLou.com>; "Barry N1EU" <email@example.com>;
Sent: Tuesday, November 26, 2002 11:03 AM
Subject: RE: [TenTec] CW Key Clicks and Filters
> In addition, you normally can not determine if a transmitted CW signal has
> clicks by listening to it with a receiver!! If you really want to know if
> CW signal has key clicks, you must observe the transmitted waveform with
> oscilloscope or if you know how to interpret correctly, with a spectrum
> analyzer or via a receivers pre-AGC IF output. Otherwise your adding a
> complete receivers design components to judge...and that's not correct!
> Just my opinion.
> -----Original Message-----
> From: Steve Ellington [mailto:N4LQ@igLou.com]
> Sent: Tuesday, November 26, 2002 5:43 PM
> To: Barry N1EU; firstname.lastname@example.org
> Subject: Re: [TenTec] CW Key Clicks and Filters
> I've had several DSP receivers...Fist the Pegasus then TS-870 and TS-2000.
> believe QST mentioned key clicks in the receiver of the IC-756pro. Their
> comment was something like....We noticed key clicks when tuned just
> of the passband of strong cw signals. Upon checking, we found that the key
> clicks were actually there and not DSP artifacts. etc etc.
> The question then becomes: How come I don't hear all those clicks on
> receivers with normal crystal filters? Here's one explanation.
> With DSP IF, I can crank the bandwidth down to 50hz. Now let's tune our RX
> to within 200hz of a strong cw signal. You will hear strong clicks. Why?
> Because they are there. That's why. No matter how clean his TX is, there's
> still clicks when you tune that close. The DSP filtered out his CW
> but not his clicks.
> So now we need to know if what we hear is really the guys clicks or is it
> something to do with all that digital processing and it's inability to
> out anything but audio tones or how it produces it's own clicks while
> to process those fast clicks.
> Since we don't have 50hz crystal filters it's hard to compare them with
> but if you have a normal xtal filted rig, try setting you filter at 250hz
> and tune just outside of where you hear his tone and you should hear the
> same clicks.
> What DSP needs now is a click filter!
> ----- Original Message -----
> From: "Barry N1EU" <email@example.com>
> To: <firstname.lastname@example.org>
> Sent: Tuesday, November 26, 2002 2:57 PM
> Subject: [TenTec] CW Key Clicks and Filters
> > W8JI deserves a lot of credit for drawing attention to
> > this serious problem. Clicks are a function of the
> > rise and fall time of the trasmitted waveform, and
> > should therefore be independent of keying speed.
> > I have to take exception to W4BQF: "I seriously doubt
> > that there were very many contest stations generating
> > key clicks during the contest as most contesters are
> > pretty knowledgeable technically."
> > I don't know which contest is being referred to, but
> > key clicks were rampant on the bands in CQ WW and
> > they're caused by poor transmitter design, and not
> > poor operators or poor receivers. Some rcvr filters
> > can emphasize the clicks, but if the clicks are being
> > transmitted you're going to receive them.
> > 73,
> > Barry N1EU
> > www.albany.net/~bg
> > __________________________________________________
> > Do you Yahoo!?
> > Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
> > http://mailplus.yahoo.com
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> TenTec mailing list
> TenTec mailing list