On Mon,9/22/2014 4:42 PM, ken.d.brown@hawaiiantel.net wrote:
If you use what I call "real FSK" there is only one tone being sent at
any one time. There is no carrier that needs to be suppressed as in AFSK
to a rig in SSB mode. There is only one tone so there cannot be any
intermodulation.
But there is a discontinuity that results from switching between the two
frequencies, which produces transients that will excite intermod. Think
about it -- even if you manage to switch at a zero crossing, the
resulting waveforms have two different slopes by virtue of their
different frequencies.
If you doubt that, look at the spectrum of your "real FSK" in an
analyzer set for high frequency resolution.
73, Jim K9YC
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