[RTTY] Funny you should mention.....

[Larry Gauthier (K8UT)]

"Nonsense?" Are you suggesting that a band full of FSK signals would sound 
no different than a band full of AFSK signals? Pullueaze.

This is one of those cases where "In theory these things are the same; in 
practice they are dramatically different." Improperly modulated AFSK signals 
wreak havoc on the RTTY bands.

-larry (K8UT)
-----Original Message----- 
From: Bill Turner
Sent: Friday, March 30, 2012 12:05 AM
To: RTTYReflector
Subject: [RTTY] Funny you should mention.....

This whole argument over AFSK vs FSK is really nonsense. Both terms, as 
commonly used by us hams are FSK, plain and simple. How one generates FSK is 
technically interesting but not relevant to the signal that goes out over 
the air. There are probably a dozen or more ways to do it, but the resulting 
signal that goes over the air is FSK, period.



The acronym AFSK has been misused by hams for so long I have no hope of ever 
correcting it, but perhaps some folks might be interested in knowing what it 
REALLY refers to.

The original meaning of AFSK was a carrier, modulated by two tones. It could 
be either AM or FM, but it was definitely not the FSK we know today, nor was 
it SSB modulated by two tones. It was a carrier with either AM or FM 
sidebands. It was NOT a simple carrier which shifted back and forth between 
two frequencies, as we all use on HF today.


In fact,FM-AFSK is still in use on VHF packet even now. AM-AFSK might still 
be in use somewhere but I haven't heard it in ages. And you will not hear 
either one on the RTTY sub bands on HF because both would be illegal.


I realize I'm swimming against the tide, but I thought you might want to 
know.

Back to the argument.


73, Bill W6WRT
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