"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
_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty
_______________________________________________
RTTY mailing list
RTTY@contesting.com
http://lists.contesting.com/mailman/listinfo/rtty
|