One of the advantages of the frequency sampling approach is that any smooth filter response can be produced. The applet below allows individual samples to be varied.

The samples are shown by red x's on a linear scale. On top of each x is the number of the scrollbar which can be used to adjust the sample. Numerical values of the samples are shown on the right.

From the frequency samples, the impulse response shown in cyan is calculated and the frequency response calculated from the impulse response is shown in orange(linear scale) and green(log scale). The length of the filter is set by scrollbar 63. Numerical values of the frequency response at a given grequency can be seen by changing scrollbars 60 and 61. Numerical values of the impulse response can be seen by changing scrollbar 62.

The image below show a filter which can be used to correct for the effects of finite sample width. The impulse response looks similar to the frequency spectrum of a zero order hold.

Image below shows a raised cosine filter. The impulse response looks like the frequency spectrum of an inverted cosine with a finite average value.

A low pass filter is shown below.

and a High pass is shown below.

COPYRIGHT © 2008 Cuthbert Nyack.