G'day Stewart,
Your 7-tone suggestion is appealing to me as it is a neat hybrid of AFK
(Piccolo), FDK (Wanjina) and IFK modes that I have been playing with for a
couple of years now.
While it uses the IFK method of transmitting two sequential tones it also
uses the frequency step direction to encode information (e. g. going from
tone #1 to tone #2 encodes a different character than going from tone #2 to
tone #1) which IFK does not. Neat. Also, although the information is
contained in the frequency difference of two tones like FDK (although
sequential), an absolute reference is required (like AFK). This is
necessary to distinguish between, say sequential tone pairs #2 and #3 and
sequential tones #3 and #4. If the stability of the transmission (and
reception) is sufficient the system could be calibrated by a space
character, but I think it would be difficult to do this by eye as stated,
although easy for a machine decoded system. The frequency difference
nature of the protocol allows that (calibrated by, say, recognising the
seqential transmission of tones #1 and #7).
Anyway, go for it. If it works, set a standard (I think spacing and timing
are the only parameters which need to be established) so others can develop
S/W and H/W to take it forward.
Good work Stewart !
73s Steve Olney (VK2ZTO/AXSO - QF56IK : Lat -33 34 07, Long +150 44 40)
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