Display spectrum of sine wave in Simulink

As a simple experiment, I am trying to generate a sine-wave and display its spectrum with the spectrum analyzer. I am expecting a narrow peak at the chosen frequency of the sine, which is 1MHz. However, what I get is a "smeared" spectrum, although the frequency should fall on a single bin. What am I doing wrong?

[Aquatris]

I think you still have leakage due to how the block works. Change the 'window length' (by default it is RBW) and it prevents the leakage. I have never used this block before so I cannot tell in detail what might be the correct way.

Answer 1

[Pramil]

You are getting smeared peaks due to spectral leakage. I assume that you are using the “Filter bank” method for frequency resolution if not I recommend using that and increase the sharpness to “1” for getting narrow peaks.

You can refer to this page under “Frequency Resolution” section to knwo more about “Filter bank” method:

https://www.mathworks.com/help/simulink/slref/spectrumanalyzerblock.html

You can also add a “Lowpass Filter Block” to supress higher frequency components which reduces attenuation due to high-frequency noise.

I have attached a sample model for you to refer.