Topband: Key clicks

Tom Rauch w8ji at contesting.com
Tue May 13 07:56:33 EDT 2003


> The bandwidth occupied by 99.999%+ of the signal power may be the spec
> that's  appropriate for limiting co-channel interference with a large
> dynamic range of signal levels. Then it's the keying envelope and not the
> keying speed that determines the occupied bandwidth.

How else would we set bandwidth in a communications system?

No matter how fast or how slow we send readable Morse code, when we listen
on a receiver or system that allows us to copy the CW, we hear clicks
exactly the same distance away from the carrier frequency. The bandwidth is
set entirely by the transmitter characteristics, with the qualification the
keying speed is such that the keyed envelope is allowed to reach zero or
full stable output.

We could never detect the peaks and valleys in the bandwidth. In order for
us to copy the CW, the receiver system can not "remember" or "store" what
happened and when on the last sideband and what will happen in future
sidebands. It is an "at the moment" response.

73 Tom



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