MATLAB: How to Set Sine Wave Frequency

Question

This question relates to a DSP Sine Wave item in Simulink (please refer to image below)…

I would like to change the waveform frequencies to (for example) 10 GHz & 10.5 GHz.

I enter the frequency into the text boxes indicated below, specifying the frequency as: 10e9 & 10.5e9

The subsequent spectrum analyzer output does not appear to reflect this…

How can this be resolved so that the spectrum analyzer displays fundamental tones F1 = 10e9 Hz & F2 = 10.5e9 Hz ?

Thank you very much in advance.

Answer 1

Make sure your time step is small enough to capture oscillations on the order of GHz. You might be generating the "correct" signal, but the sampling rate is low enough to where you're aliasing the signal