Telemetry of human electrocardiograms in aerial and aquatic environments

A technique for human electroencephalogram (ECG) telemetry that is equally useful on land and in water (i.e. amphibious ECG telemetry) with a single transmitter was developed. For the ECG on land, an electromagnetic wave of 79 MHz FM VHF was used, while for the ECG under water, a 77-kHz FM current was used. The VHF was received by an aerial of an FM radio and the current by two underwater antennas along course-marker ropes. When a subject jumped from a diving platform into the water, continuous recording of ECG signals was possible with only a short time disturbance of the signals due to change in posture of the subject before jumping. This indicates rapid switching from electromagnetic to conductive transmission. The ECGs on land and during surface or underwater swimming showed a clear difference in the QRS complex and T wave.