Topband: Re: Weak Signal Reception (EME view)

Bill Tippett btippett at
Fri Jul 18 17:15:27 EDT 2003

I wrote:
 >I recall an approximate estimate for keyed CW bandwidths is
about 4 times the keying speed.

         Turns out that was from my memory from an FCC test
question years ago...and it is incorrect!  The keyed bandwidth is
much more a function of the rise and fall times of signal waveforms,
as we're all too painfully aware of due to experience with certain
clicking radios being sold.  Here are a couple of references about
keyed bandwidth:

"Spectral Analysis of a CW keying pulse"  by W9CF

"On the Occupied Bandwidth of CW Emissions" by KF6DX (TenTec)

         Maybe the moral of this is to clean up your clicks if you
want to be heard well in very narrow filters!  ;-)

                                         73,  Bill  W4ZV

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