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A filterbank is a set of filters designed to separate a signal into different frequency bands. Each filter in the bank is responsible for passing a specific range of frequencies while attenuating others. This process is fundamental in many areas of signal processing, including audio, telecommunications, and image processing. The output of a filterbank is a collection of sub-band signals, where each sub-band contains a portion of the original signal's frequency spectrum.

The design of a filterbank involves selecting the number of filters, their center frequencies, bandwidths, and the characteristics of their frequency responses. Common types of filterbanks include uniform filterbanks, where the frequency bands are equally spaced, and non-uniform filterbanks, which can be tailored to specific applications where certain frequency ranges are of greater importance. The filters themselves can be implemented using various techniques, such as Finite Impulse Response (FIR) or Infinite Impulse Response (IIR) filters.

Filterbanks play a crucial role in signal analysis, enabling the examination of spectral content at different resolutions. They are also essential for signal compression techniques, where information in less perceptually relevant frequency bands can be discarded or represented with fewer bits. In communications, filterbanks are used in modulation and demodulation schemes to efficiently transmit and receive data across different frequency channels. The concept extends to more complex systems like wavelet transforms, which can be viewed as a type of generalized filterbank.