I have attempted to use the FMCOMMS3 board using the standard boot image and ADI Linux distribution. Using the Oscilloscope program, I set the channel 1 DDS frequency at approximately 100 kHz and set a TX frequency of 2450 MHz. I see this output on my scope:
The sinusoid is clearly visibule, but there is some high frequency component disturbing the signal. Zooming in, this is what the noise looks like:
Some sort of periodic disturbance is present in addition to the DDS wave. This is not the carrier, as if I zoom in further:
I see the fairly clean 2.45 gHz carrier sine.
Other than setting the DDS and TX characteristics, all other settings are left at default.
What would be the cause of this intermediate interfering signal?