Jerry, you are correct as long as you don't alter your BFO frequency. Many of us do, in order to maximize our audio performance.
In my sketch, I therefore set my lower sideband value as my BFO and my upper sideband value as 2*BFO. I then use this snippet:
void program(){
?if(L2==upper) L1 = FQ+L2-BFO;//Calculate 1st LO frequency(USB)
?else(L1=FQ+L2+BFO);?????????????? //Or for LSB
?si5351.set_freq(L1 * 100, SI5351_CLK2);//Program it to CLK2
?post=millis();?????????????????????????????? //Return and display?????
}
where L2 is the second LO, L1 is the first LO, and FQ is my operating frequency.
It places the signals spot-on, allowing AM reception on both sidebands without adjustment. The ultimate test. This algorithm has been in use for a couple of months now. 73, Don
Don, ND6T