The uSDX transceivers are not great but it's amazing that they work at all. An under-powered Atmel processor being able to demodulate and modulate single sideband is incredible. Hans at QRP-Labs has turned polar modulation in to an incredibly well performing radio in the form of the QMX.
What's missing is the technology of the uSDX ported to a more capable CPU and Jon has done that. It's one of a group of amazing bits of code documented here and shared here.
I've taken just on bit of it, the transmitter example and forked it here.
Not sounding great at this point but it does work. What's incredible to me is that there's no Si5351 being rapidly phase shifted, it's all done in the PICO. The circuit is very simple, even more simple than an NE602 based qrp transmitter.
I can well understand why QRP-Labs keeps their software closed source - they'd be put out of business by clone makers in minutes. Having said that, I hope we can one day have an open source equivalent to hack on. Thanks to Jon for his great work.
My analog switch chips, the FST3253, arrived smaller than I expected. My fault! I have some carrier boards but struggle to solder the tiny chips to them. Second attempt worked today.
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