A C-language program for the computation of power spectra on a laboratory microcomputer.

A computer program is described which performs power-spectral analyses on time-domain data. The program is written in the C language and incorporates an algorithm for the fast Fourier transform translated from BASIC into C. Sequential segments of time-domain data are accessed by the program, transformed to the frequency domain, and ensemble-averaged to generate smoothed spectra. Specific application of the program to the detection of high-frequency oscillations in the phrenic neurogram of the cat is addressed. Thus, 100 successive 512-point fast Fourier transforms were found to accurately reveal the relative strength (power) and frequency position (spectrum) of multiple peaks in this respiratory motor pathway. Because C language programs are very transportable, this program should run on machines other than our LSI 11/23, provided a C-compiler is available.