Medical applications of analogue and digital telephone data links.

The increasing use of digital computer techniques for the analysis of signals such as the EEG, ECG, plethysmograms and cardiac output curves has led to the use of multichannel analogue frequency modulation telephone data links in the forward direction from the patient to the computer and digital links in the return direction. Single-channel analogue links are also being used for the surveillance of cardiac pacemaker patients and the television Viewphone offers the possibility of a visual contact between two centers. Examples will be given of the use of these various forms of telephone link.