Signal Spectra 2

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Instruction Manual (German)

Signal spectra

In this experiment we take a closer look on a sinc-pulse. Especially the relationship between the pulse shape (time domain) and the spectrum (frequency domain).

At first we should focus on the sinc-pulse itself. The fundamental parameters are the impulse height or amplitude and the impulse width.

sinc pulse parameters

In this example the sinc-pulse is 4V high and 250μs wide.

The spectrum has similar parameters. More particularly its width and cutoff frequency. To view the whole spectrum the negative frequencies have to be visualized.

Sinc spectrum analyzer properties
Sinc spectrum parameters

As you can see, the spectrum width f is twice the cutoff frequency fc.


Start the experiment and have a look on the oscilloscope and the spectrum analyzer.

Now open the filter properties dialogue and change the cutoff frequency to 1MHz.

Filter properties open dialogue
Filter properties dialogue

Look how the pulse shape and spectrum change. What relationship do you see?

Scope 1Mhz
Spectrum 1Mhz

Finally change the impulse response length and look at the oscilloscope and spectrum analyzer.

Filter properties dialogue

How does this affect the pulse shape and spectrum?

Scope 40T
Spectrum 40T


Also take a look at the other simulation apps to get further into signals and spectra.

Signal Spectra 1, Pulse Spectra