A program for cycle-by-cycle shape analysis of biological rhythms. Application to respiratory rhythm

A computer program for cycle-by-cycle analysis and quantification of biological rhythms, written for an Apple II microcomputer with 48k RAM is described. The program comprises 4 steps: (1) file constitution suitable for biological data collecting; (2) signal digitalization at a sampling rate up to 1 kHz with storage in central memory; (3) determination of each cycle's limits (delimitation parameters being defined by the user; following delimitation, cycles may be dropped or saved for further analyses); (4) cycle-by-cycle harmonic analysis (fast Fourier Transform algorithm). The program is written in BASIC Applesoft, hardware-dependent functions (analog inputs, graphic display and random access disk storage) are implemented in subroutines (partly assembler) which may be easily modified. The program, consisting of 4 chained procedures is run interactively, although procedure (4) may be run automatically. Analysis of human ventilatory airflow signal with this program is given as an example of cycle-by-cycle shape analysis of a biological rhythm.