First make sure the volts per division on channel 1 and 2 are the same, that the probes on both channels are set to 1:1, and that both channels are DC coupled. Then press the "Horiz" button at the top of the scope in the "Horizontal" section. Turn the knob in the middle on the left with the circular arrow icon to "XY" which will be displayed on the screen. Press the knob in to select XY.
Make your 1024-point complex input array X[N] an external (global) array. This causes X to be stored in a fixed location in memory. When you make your spectrum analyzer, your interrupt service routine declared with the keyword "interrupt" can have no arguments, so you must pass arrays to it as external arrays.
Make sure the SSB samples sent to the DAC of the codec do not overflow the dynamic range of the integer 16-bit two's complent number format for the DAC. You can test for overflows by measuring the SSB signal spectrum with the oscilloscope. You should only see a distinct line at the pilot tone frequency and one at the upper sideband frequency when the display format is set to volts rms rather than dB. Other lines indicate overflows.
