[ICOM] FSK

[C.Whitaker]

de WB2CPN   Some Trivia.
Frequency Shift Keying, (FSK), produces two or more Radio Frequency Tones
over the air, and that can can be accomplished a few different ways, all 
with
the same result.  Radio Teletype used an 850 cycles-per-second shift 
between
Mark and Space,  but ham radio, and other systems, use a more narrow shift,
often half that, or less.

"Digital" transmission systems usually use a few simultaneous tones,  
and is not
normally refereed to as FSK.    Sometimes called  "Audio FSK" Anywhere from
just two tones, up to eight or sixteen tones.  In order to maintain an 
established
total power on the channel. the more tones used requires that each tone 
have
a reduced amplitude.   This is the most common form of date transmission in
this day and age.

Of course, it all began with a mode where the carrier frequency was 
keyed on
and off by skilled radio operators.  With the "key" down the radio 
transmitter
produced a continuous radio frequency signal.  Hence, "CW",
meaning "Continuous Wave".   EOT  (End Of Trivia)
73  Clete in PA.  All for my files.