FIR Filters by Frequency Sampling, Transition Samples 1.

Cuthbert Nyack

In this applet, the length of the filter is set by scrollbar 63. Scrollbar 30 sets the type of filter ie LP, HP, BP and BS. The number of transition samples is set by scrollbar 33 and the numerical values of the transition samples is shown on the right. The numerical value of each transition sample can be set to 8 decimal places eg the first transition sample is value of scrollbar(0) + (1/100) value of scrollbar(1) + (1/10000) value of scrollbar(2) + (1/1000000) value of scrollbar(3) + (1/100000000) value of scrollbar(4). The second transition sample is set by scrollbars(5 - 9) etc.
The value of the pass band samples are set to 1 and the stop band samples are set to zero.

For LP the number of samples in the pass band is set by n1(31).
For HP the number of samples in the stop band is set by n1(31).
For BP the number of samples in the first stop band is set by n1(31) and the number of samples in the pass band is set by n2(32).
For BS the number of samples in the first pass band is set by n1(31) and the number of samples in the stop band is set by n2(32).

dB(57) sets the dark red reference line and dBS(56) sets the dB/div.

In this applet, the samples are plotted on a linear scale as they are often shown in books.

Images below show LP, HP, BP and BS filters with 3 transition samples.

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