GB810730A - Improvements in or relating to devices to be worn on the human body to reveal the wearer's position if he is accidentally buried - Google Patents

Abstract

810,730. Radio signalling. WENDT, W., WENDT, E., and WENDT, H. Feb. 16, 1956 [Feb. 16, 1955], No. 4881/56. Class 40 (5). [Also in Group XXXVIII] A tell-tale portable radio transmitter identifying the position of the wearer should he be buried in a disaster, and used in conjunction with an appropriate search receiver, comprises a wristlet case (Fig. 3, not shown) from which projects a short aerial A (Fig. 1) energized by a parallel resonant circuit LC and a three-electrode transistor Tr supplied by a battery connected at B to generate detectable HF oscillations. A temperature-sensitive semi-conductor member T has a small resistance at normal body temperature and a high resistance at lower temperatures and is arranged to diminish or suppress radiation in response to body cooling after death. A microphone UE responsive to heat pulse or lung sounds may modulate the radiated signals in life. The temperature-sensitive semiconductor may be replaced by a linear resistance (Fig. 2, not shown) so that the device responds to body sounds alone.