Abstract: An FM transmitter especially for physiological signal telemetry includes a transistor oscillator having a collector-to-base capacitance that is part of its tuned circuit. Means are disclosed for controllably varying the collector-to-base capacitance only in response to impressed physiological or other signals to provide FM modulated signals for aerial transmission to any suitable receiver. Means including cooperative constant emitter current and constant collector voltage DC biasing circuits are disclosed for eliminating undesirable, changing temperature induced frequency variations. Means are further disclosed for neutralizing undesirable antenna loading induced frequency variations. The system is capable of accepting multiplexed inputs.

Abstract: A diversity telemetry receiver having plural spaced antennas includes a plurality of RF FM receiving channels each associated with an antenna, and each comprising one or more RF amplification stages, a mixer stage, and one or more IF stages along with an analog circuit providing a plurality of control signals that represent the relative signal level of the associated channel, an FM detector, and a signal level responsive switch operative to selectively apply the IF signal from the channel having the strongest signal level to the FM detector. The output of the FM detector which forms the system output is free of switching transients due to the operation of the level responsive switch prior to FM detection. A data recorder may be connected to receive the FM detector output, and a display may be connected to the level responsive switch to provide a visual indication of the channel having the strongest signal.