A PORTABLE TAPE RECORDER FOR MONITORING ABULATORY SUBJECTS
Lawrence, Courtlandt B.
This thesis describes the design and construction of a portable 4 channel magnetic tape recorder with an endless loop tape storage of 65 minutes. Although primarily designed for recording electrocardiograms the recorder is capable of recording signals with frequencies up to 200 cycles/second. The total recorder weight is 3.0 lbs plus batteries weighing .1 lbs per hour of recording. Although the recorder uses frequency modulation, delta modulation is discussed as an alternative to frequency modulation. A system that has been built for transmitting electrocardiograms via telephone is also described.