[WriteLog] What's wrong with AFSK? was - 5 bit mystery unraveled

[llindblom at juno.com]

-- Bill Turner <wrt at dslextreme.com> wrote:


_________________________________________________________

When AFSK is done properly, it is indistinguishable from FSK at the
receiver end.  The problem is it can easily get out of adjustment,
mainly by overdriving the audio stages in the transmitter.  When this
happens, the transmitter often outputs the signal at two or more
frequencies.  I often see this during contests.

-----------------------------------------------------------------------

I 100% agree with Bill's comment about overdriving the audio stages with AFSK.  While I was playing around in WPX RTTY several times on 10 meters my "clear run frequency" was destroyed by what I thought was someone moving in a 100 Hz or so away from me.  Instead each time when I checked it was the same LU who was CQing about 2 KHz away from my frequency with a signal that had to be over driven as even with my AGC off kicking in the 250 and 330 Hz filters didn't do any good. If nothing else, it is a sneaky method to insure everyone else gives you a clear frequency;-)

73 W0ETC