Audio frequency spectrum analysis using MOS memory elements

The speed of present-day logic elements is such that it is possible to effect real-time spectrum analysis of audio frequency signals by means of digital hardware. This paper describes a structure that computes the discrete Fourier transform of a 400-point time sequence in 10 ms. This allows the real-time analysis of signals having components in the range from dc to 5 kHz. A high-speed bipolar arithmetic section is used in conjunction with relatively slower MOS shift registers and READ-ONLY memory to provide an efficient and economical design.