I working on a Simulink Signal Spectrum Analyzing on my own, and I'm stuck

Hi, I am working on my own to understand Simulink Spectrum Analyzing Fundamentals.

My curiosity is about the multiplication of the Rectangular and Sine wave in Simulink.

Note: I've added my .slx simulink file too.

So, I was trying to measure:

1-bandwidth,

2-repetition frequency,

3-pulse width,

4-sample rate

of my scope and spectrum analyzer.

Also do the values match with the signal in time and frequency domain?

My Configuration:

My Scope Output

My Scope Output (Zoomed Version):

My Spectrum Analyzer Output:

Answer 1

[Sudarsanan A K]

Hello Cikalekli,

I understand that you are trying to understand the fundamentals of the "Spectrum Analyzer" block from 'DSP System Toolbox'. I also note that you are curious about visualizing the spectrum of a signal which is the product of a rectangular wave and a sine wave, and would like to measure the bandwidth, pulse repetition frequency, pulse with, and sampling rate.

I notice from your model configuration that you currently have used the "Rectangular Waveform" block as the input to the "Spectrum Analyzer" block and to a "Scope block".

I have attached below the snapshots showing an example model set up and corresponding block properties for your reference:

Note that I have used the frequencies as 10 Hz for the rectangular wave and 200 Hz for the sine wave. The spectrum of their product is visualized in the "Spectrum Analyzer" as show below:

As you can see, the spectrum of the rectangular wave is now translated and centred at the sine wave's frequency. You can try modifying the properties of rectangular waveform and and observe the changes in the "Spectrum Analyzer" accordingly.

For a better understanding of the "Spectrum Analyzer" block in Simulink with examples, you can additionally refer to the following MathWorks documentation link:

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

I hope this helps you in gaining a better understanding of the "Spectrum Analyzer" block in Simulink.