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Can a FIR filter be used regardless of the cut off frequency?
So assuming the impulse response has a constant decay rate, shouldn’t an FIR filter of fixed length being equally good (or bad) regardless of cutoff frequency? You’re right: the required filter order is approximately inversely proportional to the desired transition bandwidth Δ ω, regardless of the cut-off frequency.
How to calculate the transition bandwidth of a filter?
That article suggest to use, as the filter length N, an odd number close to 4 / b, where b is the required transition bandwidth. This is a good basic rule. However, in my Filter Design tool, I actually don’t use 4 in the numerator of the expression, but a different value for each window type.
Is it possible to optimize the filter length exactly?
It is clearly possible to optimize the filter length exactly, given the transition bandwidth and the criterion used to measure it. E.g., you could start from the values given above, and then vary the number of taps in steps of 2 (to keep the number odd) and check some criterion for the width of the transition region.
What should the transition zone be for a low pass filter?
The red vertical lines in Figure 1 show the edges of the requested transition region of 0.1, for a low-pass filter with a cutoff point of 0.25. A filter with the requested roll-off has the edges of its transition zone close to the lines, but not outside of them.
Is it possible to design an ideal fir lowpass filter?
Because the impulse response required to implement the ideal lowpass filter is infinitely long, it is impossible to design an ideal FIR lowpass filter.
Which is the best algorithm for FIR filter design?
The Parks-McClellan FIR filter design algorithm is perhaps the most popular and widely used FIR filter design methodology. The syntax for firls and firpm is the same; the only difference is their minimization schemes.
What are the deviations in a practical FIR filter?
These deviations are depicted in the following figure: Practical FIR designs typically consist of filters that have a transition width and maximum passband and stopband ripples that do not exceed allowable values.