Testing a digital filter with White Noise

What is the procedure to test a digital filter? Does passing a white noise through it and visualizing the frequency content output a valid test?

From my trials with two filters, I observed that the frequency content after filtering does resemble the filter shape as such.

and

Is this a correct way of testing? Any insights on how to test a digital filter would be really helpful.

I do apologize, if this is more of a signal processing question rather than a MATLAB question.

Answer 1

[Dimitris Kalogiros]

Hi Krishna

Your test, although primitive, gives a first feeling of how the filter performs.

But I must highlight two points

• The figures on the right (frequency response of the filter) are expresed in dB. Thus they are not look similar with the figures on the left. In fact, if you transform the signals in dBs, you will get the same shapes
• Frequency response of the filter is adequate to give all the info a designer needs in order to evaluate a filter.