Re: QMX and SSB -- how?
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The STM32F446 microcontroller has two 12 bit DACs. A DAC output is used to control the amplitude of the transmitter output; it's not done with PWM. The current firmware only uses that to control the rise and fall times of CW transmissions. The uSDX already?does SSB using this method. The QMX should be able to do a much better job of it: more powerful?microcontroller and finer control over the signal amplitude. (The uSDX uses PWM for that.) We will have to wait and see whether it will be good enough to satisfy Hans. On Fri, Sep 1, 2023 at 10:33?PM Stephan Ahonen KE0WVA <stephan.ahonen@...> wrote: It's pretty intuitive if you think about what an FM signal looks like in IQ representation, and what an AM signal looks like in IQ representation. You can take any signal in IQ space and determine its FM component and its AM component. The QMX can rapidly retune its oscillator thousands of times a second, and it can PWM the transistor feeding the PA, to recreate the FM and AM components respectively. This will be pretty kickass if it can be pulled off with this hardware. |
Shirley Dulcey KE1L