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The attached simulink file is a very simple model of a signal source with a scope and spectrum analyser attached.

The signal source produces a constant value of 1 over the entire simulation time. The spectrum analyser has been setup with a HANN window.

From the spectrum analyser you can see the value at zero hertz is 30 dBm. With Hann windowing I was expecting the value to be about 6 dBM less than this ?

For simple signal analysis such as this I find simulink incredible difficult. Any suggestions for easier to use signal processing software would be more than welcome.

Regards, derick007

RE: simulink

You definitely have something odd. 1 what? 1 Vrms? 1 Vrms^2/50 = 20 mW -> 13 dBm, not 30 dBm. I expect 17 dB less with a rectangular window.

Why don't you try putting a few frequency sources in your window? That way you can see if your window shape is behaving as you expect.


RE: simulink

Check the area of the Hann window. A DC output signal will be scaled by the area of the window divided by the number of samples.

RE: simulink

The value for 0Hz is 30dBm = 0dBW = 1W for a Hann (and for most other) window, because you are inputting a constant 1 signal.

If you want to input a pulse, you should adjust the parameters Pulse Generator>Pulse Width and Pulse Generator>Phase properly.

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