FIR Filter with Frequency sampling, log samples.

Cuthbert Nyack
Although numerical techniques are necessary to get high stop band attenuation, the applet below attempts to illustrate the flexibility of this approach. Provided stop band attenuations of ~ 80dB are acceptable, then the visual interactive approach can be used. The achievable stop band attenuation here is limited by the resolution of the samples.

The samples are shown by the red x's with their controlling scrollbar number in white. Numerical values of the samples can be seen in dB on the right and on a linear scale on the left. Numerical values of the impulse response can be seen by changing scrollbar 62.

The following images show the flexibility of this approach. The first two images show low pass filters.

The next 2 images show high pass filters.

The next 2 images show band pass filters.

below is a possible band stop filter.

A notch filter is shown below.

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COPYRIGHT 2008 Cuthbert Nyack.