> It seems to me that the cognoscenti prefer FSK to AFSK. I have never
> seen any reasons for this preference, probably because I haven't looked
> in the right place. So, what's the problem with just sending AFSK to
> the radio, thereby eliminating the need for an AFSK to FSK converter?
Jim, what are you referring to here regarding AFSK to FSK converter? You
don't need a converter. The 5-bit Baudot code is generated by your
software, although depending on your rig, you need some sort of "interface"
between th serial port signal and your rig's FSK input. In the case of the
FT-1000MP, MARK-V, and IC-756PRO or PROII, this can be as simple as a 1K
resistor, whereas in other rigs a transistor or opto switch might be
advised.
Others have commented about the possibility of overmodulation with AFSK, and
that's a big point. Interestingly however, in some rigs like the FT-1000MP,
even when you wire for FSK using the rig's FSK input, your digital signal is
actually fed to an internal -AFSK- generator inside the rig, so you're in
fact running AFSK ANYWAY! HI However, it's still a configuration that
leads to better signals and less frequency hassle as the others have
mentioned.
For reasons I'm not sure I understand, beginners seem to start using AFSK.
However, after some experience, many RTTYers make the change to FSK. GL -
73, John, WA9ALS
P.S. The next issue of NCJ will have an article regarding AFSK vs FSK and
how it affects perceived frequency.
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