A Method of Data Access Address Generation Based on Hybrid Base FFT

Abstract

The invention provides a data access address generation method based on a mixed base FFT. The method includes first providing expressions of a time domain index and a frequency domain index of the mixed based FFT and indicated through two different bases; then substituting the two expressions into a DFT expression, resolving the obtained expression to obtain an iteration recursion equation of DFT operation, acquiring a general iteration expression of any grade according to the equation, analyzing the iteration expression to obtain addresses of a required operand and a twiddle factor, finding that the addresses of the operand and the twiddle factor can be obtained through an accumulator based on the mixed base expression according to a law generated by the addresses of the required operand and the twiddle factor, and finally utilizing the accumulator to obtain the access addresses of the operand and the twiddle factor based on the mixed base FFT. By means of the method, generation of the addresses of the operand and the twiddle factor is achieved by means of simple displacement of the accumulator, address generation complexity is reduced, and the method has positive significance on hardware achievement of any mixed base FFT.

Description

technical field [0001] The invention belongs to the technical field of digital signal processing, and relates to a low-complexity mixed-base FFT (fast Fourier transform) address generation method. Background technique [0002] With the development of digital signal processing technology and large-scale integrated circuits, the importance of FFT algorithm is self-evident, and it is widely used in various scientific and engineering fields, such as radar, sonar, communication, etc. requirements are getting higher and higher. [0003] Traditional design algorithms mainly focus on radix-2 and radix-4 structures, which are widely used because of the simplicity of the butterfly unit and the low complexity of address generation. For base 3, base 6 and other points of FFT because of its complex butterfly processing unit and address generation are usually applied in the form of N=q×2 m In the FFT processor of length, q is an integer value such as 3, 5, etc., and m is a power exponen...

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Problems solved by technology

[0004] At the same time, the traditional radix-2 and radix-4 FFT algorithms limit the number of points to the power of 2 or the power of 4, which limits the range of options for the number of points

For some applications, such as SAR (Synthetic Aperture Radar) signal processing, due to the limitation of processing time and area, the number of points processed cannot be extended to satisfy the radix-2 or radix-4 FFT algorithm, especially for the FFT with a large number of points, otherwise It will prolong the calculation time and consume more storage space

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