An approach to DFT calculations using standard microprocessors

The use of the DFT as an everyday tool is now commonplace, principally due to advances in hardware technology. Special-purpose VLSI chips for signal processing are available. In this paper, we describe an approach which marries the Winograd Fourier Transform Algorithm (WFTA) with a state-of-the-art 16-bit general-purpose microprocessor for the purpose of DFT calculation. The heart of the approach is the real-input 240-point WFTA, which has been carefully optimized for time and space. In particular, an implementation for the 10-MHz M68000 executes in 10.8 ms. A simple hardware module is described which implements the optimized software. The use of the module for the inverse transform and for the complex case is also discussed. Advantages to the approach taken in this paper are the low cost/performance ratio and the general-purpose nature of the system that allows many non-signal-processing functions to be performed by the microprocessor.