[GreenKeys] True FSK vs AFSK

[Kevin H. Phillips]

	> On Fri, 4 Feb 2022, Paul Kasley wrote:

	>>

	>

	> However, is that the way modern radios actually generate FSK? and
CW?

	> Or do they actually generate AFSK internally and put it into the
audio

	> chain?

	>

	When I used a Yaesu FT-1000D I discovered that it was keyed (externally)
like a "true" FSK transceiver but that, internally, the signal
was being converted to AFSK and that was what was being
transmitted.  I realized this after being told my on-air signal was
overdriven.


	 


	I later switched to an FTDX-5000.  The manual for the 5000 has a
note under RTTY Operation that states:  "In the FTDX-5000,
"RTTY" is defined as an "FSK" mode, whereby the
closing and opening of a keying line (to ground) causes the Mark/Space
tones to alternate.  The RTTY mode is not an AFSK based mode in this
transceiver and the AFSK output tones from a TNC will not cause
Mark/Space shifting to occur.  Use the "Packet" mode for
AFSK-based Baudot and other data modes."


	 


	After switching to the 5000 I never had problems with overdriven signal
again, which is one reason I bought the transceiver.  There is
definitely crud on the air from digital modes transmitted without proper
audio adjustment.


	 


	The only other "modern" transceiver I've had RTTY experience
with was an ICOM IC-765 which was also "true" FSK.  So, I
can't speak to the really more modern rigs.


	 


	73


	 


	Kevin


	W5TTY

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20220204/bf46bbd1/attachment.html>