Efficient Multirate Filtering

Contents	Abstract	Conclusion	Figures	FREE software
Introduction	Conversion	Narrow-Band	Half-Band	MATLAB Scipts

Half-Band Filter Design:

In this section, we expose in detail FIR and IIR half-band filter design.
Filters that divide the frequency range of a discrete-time system into two equal parts are known as half-band filters.
The FIR filters are most often used as half-band filters due to their linear phase response.
A half-band IIR filter can have fewer multipliers than the FIR filter for the same sharp-cutoff specification.
Elliptic IIR filters are the most efficient.
The main disadvantage of elliptic IIR filters is their very non-linear phase response.
To overcome phase nonlinearity one can use optimization to design an IIR filter with an approximately linear phase response (Sarama-aho, 1999) or apply the double filtering technique with the Powell and Chau modification for real-time processing (Powell, 1991), (Djokic, 1998), (Lutovac, 2000, March).

For the appropriate usage of digital filter design software in half-band filter design, it is necessary to calculate the exact relations between the filter design parameters in advance.
In this section, we present the design procedure, which starting from the specifications, provides the exact adjustment of all half-band filter parameters.

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Last updated September 9, 2008