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Author Topic: Why Does WSJT-X FT-8 "Wide Graph" Use Audio Frequency Versus RF Frequency?  (Read 316 times)

VK6HP

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Jim,

The QDX is an interesting radio and worthy of much better treatment than it got by QST.  I don't know if you saw the earlier thread with my (and other) comments:

https://www.eham.net/community/smf/index.php/topic,138253.msg1288342.html#msg1288342

While the method of deriving the required synthesizer offset is clever, in line with the current discussion it's ultimately unnecessary - WSJT-X (for example) could just send the required offsets numerically.  A small practical concern I have relates to whether the present audio method will return the required accuracy for long-duration modes on LF/MF.

Envelope shaping for FSK and CW is best done in the non-linear PA, as in a number of LF/MF designs currently in use.

Hans (G0UPL, the QDX designer) made the comment about audio being the lowest common denominator and you're right about the latency in adopting new approaches.  That's the main reason I was disappointed with the quality of the QST "review" of Hans' product; if any entity has a role in promoting forward thinking it's certainly the ARRL.

73, Peter.



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