On Jan 19, 2013, at 3:33 PM, Paul wrote:
> Does anyone know if the FT-1000D is true FSK or is it AFSK?
Keyed AFSK. Not Direct FSK.
Look for a switch-tail ring counter with a set of resistors that has the weight
of a sine table :-). That is the way it appears in the FT-990 schematics. The
rig clocks the ring counter at different clock frequencies to produce Mark and
Space tones, and very conveniently, the resistor weights produce a phase
continuous audio sine wave output. They change the clock frequency to get the
different tone pairs (low tone, 2125/2295, etc). Actually quite cleaver of
Yaesu engineers.
The follow up FT-1000MP is Direct FSK (using direct digital synthesis VFO).
73
Chen, W7AY
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