Filter bank

Filter bank

A filter bank is an array of band-pass filters that separates the input signal into several components, each one carrying a single frequency subband of the original signal. It also is desirable to design the filter bank in such a way that subbands can be recombined to recover original signal. The first process is called analysis, while the second is called synthesis. The output of analysis is referred as subband signal with as many subbands as there are filters in filter bank.

The filter bank serves to isolate different frequency components in a signal. This is useful because for most applications some frequencies are more important than others. For example these important frequencies can be coded with a fine resolution. Small differences at these frequencies are significant and a coding scheme that preserves these differences must be used. On the other hand, less important frequencies do not have to be exact. A coarser coding scheme can be used, even though some of the finer details will be lost in the coding.

The vocoder uses a filter bank to determine the amplitude information of the subbands of a modulator signal (such as a voice) and uses them to control the amplitude of the subbands of a carrier signal (such as the output of a guitar or synthesizer), thus imposing the dynamic characteristics of the modulator on the carrier.

If the filters are combined with downsampling or upsampling then it is useful to represent that combination by a polyphase matrix.With the polyphase matrix you easily answer the question for the perfect reconstruction property of a filter bank.

ee also

*Wavelet
*Quadrature mirror filter
*Polyphase DFT, Polyphase FFT or WOLA (Weighted OverLap and Add), an efficient multi-channel filter bank method. see http://www.rfel.com/products/Products_polydft.asp for example.

References

*Cite book
author=J. Harris, Fredric
authorlink=
coauthors=
title=Multirate signal processing for communication systems
date=2004
publisher=Prentice Hall PTR
location=Upper Saddle River, NJ
isbn=0-13-146511-2
pages=


Wikimedia Foundation. 2010.

Игры ⚽ Нужно сделать НИР?

Look at other dictionaries:

  • filter bank — noun An array of band pass filters that separates the input signal into multiple components, each one carrying a single frequency subband of the original signal …   Wiktionary

  • Bank filtration — is a type of filtration that works by passing water to be purified for use as drinking water through the banks of a river or lake. It is then drawn off by extraction wells some distance away from the water body. The process may directly yield… …   Wikipedia

  • Polyphase quadrature filter — A polyphase quadrature filter, or PQF, is a filter bank which splits an input signal into a given number N (mostly a power of 2) of equidistant sub bands. These sub bands are subsampled by a factor of N, so they are critically sampled.This… …   Wikipedia

  • Quadrature mirror filter — In digital signal processing, a quadrature mirror filter is a filter most commonly used to implement a filter bank that splits an input signal into two bands. The resulting high pass and low pass signals are often decimated by a factor of 2,… …   Wikipedia

  • Gabor filter — A Gabor filter is a linear filter whose impulse response is defined by a harmonic function multiplied by a Gaussian function. Because of the multiplication convolution property (Convolution theorem), the Fourier transform of a Gabor filter s… …   Wikipedia

  • Gammatone filter — A gammatone filter is an impulse response filter used in many models of the auditory system. It is the most widely used example of auditory filters. It is described by the equation:g(t) = at^{n 1}cos(2pi ft + phi) e^{ 2pi bt}, ,wheref is the… …   Wikipedia

  • Slow sand filter — Slow sand filters are used in water purification for treating raw water to produce a potable product. They are typically 1 to 2 metres deep, can be rectangular or cylindrical in cross section and are used primarily to treat surface water. The… …   Wikipedia

  • Diesel particulate filter — A diesel particulate filter (top left) in a Peugeot Off road DPF Installa …   Wikipedia

  • Al Taqwa Bank — The Al Taqwa Bank (occasionally Bank al Taqwa or simply Al TaqwaNewsweek. (2001). [http://www.msnbc.msn.com/id/3067473/site/newsweek/from/RL.5/ Attacking the Money Machine ] . MSNBC.com . Retrieved February 14, 2007.] ) is a financial institution …   Wikipedia

  • Dogger Bank itch — is a cutaneous condition characterized by an eczematous dermatitis caused by exposure to the sea chervil, Alcyonidium diaphanum, a seaweed like animal colony.[1]:431 The disease, common in fishermen who work in the North Sea, has been recognized… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”