Quadrature mirror filter
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In digital signal processing, a quadrature mirror filter is a filter bank which splits an input signal into two bands which are usually then subsampled by a factor of 2.
The filters are related by the following formula:
where ξ is the frequency, and the sampling rate is normalized to 2π.
In other words, the sum of the magnitude response of the high-pass and low-pass filters is equal to 1 at every frequency.
Orthogonal wavelets -- the Haar wavelets and related Daubechies wavelets, Coiflets, and some developed by Mallat, are generated by scaling functions which, with the wavelet, satisfy a quadrature mirror filter relationship.
Also called a conjugate mirror filter.
[edit] See also
- Quadrature Mirror Filters tutorial 1 from cnx.org
- Quadrature Mirror Filters tutorial 2 from cnx.org