Transmission and reception of sheep heart-rate

摘要

Abstract A sheep heart-rate transmitter has been designed to work from an animal grazing freely in a large paddock. The heart beats key the transmitter, and the receiver (at a difference frequency of 2,500 c/s) gives an audio output at 2,500 c/s at a pulse repetition frequency depending on the sheep's heart rate. This is much better both for aural counting and for electronic counting than a genuine heart beat. The receiver has no tuning controls and may be worked by operators who are completely unskilled in electronics. Economy in the use of the tape recorder is obtained by switching on for one minute in every 12.