Design and development of a multi-channel signal-acquisition system for recording an apnea waveform database

A signal-acquisition system for recording high-fidelity physiologic waveforms from infants in a sleep lab is described. The acquired signals are intended to be annotated and assembled into a multiple-channel database to be used for testing the effectiveness of apnea monitors. Such a database would have significant advantages over present patient simulators, which supply simple artificial waveforms. The custom recording system described overcomes many limitations typically encountered with commercially-available equipment. For instrumentation, the system uses commercial monitors which have been internally modified for wine bandwidth and DC response. Analog outputs from monitors are digitized with locally dedicated, oversampling, delta-sigma analog-to-digital (A/D) converters to minimize acquisition noise and distortion. The resulting data is transmitted over optically-isolated, twisted-pair, serial transmission links to a data-collection subsystem. This subsystem is used to interface the digitized instrumentation outputs to a high-speed data port (HP-GPIO) on a 68040-based computer operating under UNIX. The computer provides system control, storage, user interface, and display functions. This acquisition system is flexible and modular, which allows signal channels to be easily added or removed without hardware modification