## Abstract

A new DFT computation method based on a subband decomposition is outlined for one- and two-dimensional (2-D) real-valued finite-length sequences. The two distinct parts of the algorithm, a preprocessing Hadamard-transform stage and a 'correction' stage are interpreted as a filter bank plus a recombination network, and are compared to the corresponding filter bank interpretation of the direct DFT and the classical FFT algorithms. The preprocessing stage decomposes the original sequence into a set of smaller length subsequences approximately separated in the spectral domain. The overall DFT is then given by a weighted sum of smaller length DFTs with the weights determined by the recombination network. The frequency-separation property of the subsequences permits elimination of the subsequences with negligible energy contribution from the DFT calculation thus resulting in a fast approximate DFT computation method. Various implementation schemes for the subband DFT computation method are outlined. As a first extension, adaptive versions are described, finding the band(s) of interest automatically. Furthermore, a generalized preprocessing stage as well as the extension to the 2-D case are addressed.

Original language | English |
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Pages (from-to) | 261-277 |

Number of pages | 17 |

Journal | Signal Processing |

Volume | 41 |

Issue number | 3 |

DOIs | |

Publication status | Published - Feb 1995 |

Externally published | Yes |

## Keywords

- Adaptive FFT
- Approximate DFT computation
- Discrete Fourier transform
- Spectral analysis
- Subband FFT

## ASJC Scopus subject areas

- Control and Systems Engineering
- Software
- Signal Processing
- Computer Vision and Pattern Recognition
- Electrical and Electronic Engineering