The spectrum of a square signal showing ghost frequencies in comparison to the expected result which could be proved by using a spectrum analyzer.
This also happens in demo mode.
Demo mode :
square (de: Quadrat) 2MHz, 1V, no offset
Expected frequencies with Duty Cycle 50%: 2MHz and odd harmonics
Result: Much more frequencies than expected, partially with high levels.
Using Blackman Harris, BINS 262144, total frequency 9.766MHz, modus: (de:) Größe
This effect caused me some time, looking for the sources of these ghost-emissions in real installations.
This seems to be bug in the FFT-software.