An 8-Channel, ultrasonic, marine bio-telemetry transmitter utilizing C/MOS digital integrated circuits

Up to 8 multiplexed channels of shark behaviorial data at sea are obtained with a 40 KHz acoustic transmitter with a range exceeding 5 km and a life of up to 1 week. Conservation of battery power is achieved with complementary metal-oxide semiconductor (C/MOS) integrated circuits and a pulse-interval data format of 10 ms pulses at intervals between 200 ms and 2 sec. A multivibrator oscillator is used to control the operating frequency which is essentially independent of temperature and pressure, and decreases slightly with battery voltage (<800 Hz/ 2-volt drop). An optional crystal oscillator maintains constant frequency. The pulse repetition rate is not significantly affected by voltage, pressure, and temperature. Fail safe devices ensure operation in the event of sensor or multiplexer failure.