Oh, what a sandstorm!
I write once more as I got an idea that perhaps clears out, or not, way
of thinking for those who are not RF experts.
We all know, (do we?), what SDR rig is. Look for webSDR receives
(Googling...) it gives a view if SDR is not familiar.
OK!
WSJT-X software turns your old war horse (rig) to a narrow band SDR
receiver adding a new IF stage 200-3000Hz to it, depending your rig's
audio fllter passband. WIth old rigs it can be just over 2000Hz, with
new ones nearly 4000Hz.
Using waterfall you can tune your SDR receiver, the green marker, to
receive a certain station. As being an SDR receiver you naturally can
receive also other stations over whole (audio) IF at same time.
But the one you tune in by moving green marker is your receiving frequency.
Same way you tune your transmitter by moving red marker. If you have
"hold TX freq" checked you and set your TX where ever you want over the
(audio) IF.
In that case you will have a split qso where you transmit on different
frequency as you receive.
If you set your TX red marker over the green marker, or have "hold TX
freq" unchecked when software does the TX moving, you will have normal
one frequency qso, no split.
The nature of SSB, as explained here, is to produce a carrier to dial
frequency+audio frequency (when using USB). Properly tuned SSB rig does
not send the dial frequency carrier, it is muted by balanced modulator,
it sends just the dial frequency+audio frequency product. The width of
carrier is the width of FT8 signal, 50Hz.
Perhaps thinking wsjtx software as additional IF stage that gives also
for old rig some SDR properties could be good way to approach this off
topic subject.
"Split operation" in settings has nothing to do with this. It is
wsjt-x's "artificial intelligence" to optimize TX audio filter usage, if
user allows it by selecting "rig" or "fake it".
Whether or not this "artificial intelligence" is used it does not change
your RX and TX tuning (red and green markers) on RF spectrum, I.E. does
not cause any "split".
Test with frequency counter. Your TX RFcarrier does not change when
selecting "none", "rig" or "fake it".
And now this subject has been done by me.
--
Saku
OH1KH
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