Tracking Fishes With a Microwatt Acoustical Receiver -An Archival Tag Development

This paper presents the design of an ultralow-power acoustical receiver circuit intended to track small aquatic animals. The receiver forms a crucial component of a versatile data logger capable of sensing and storing a variety of biologically important data such as geographic position, ambient temperature, pressure, etc. The size of the final tag will be determined by the size of the cylindrical hydrophone, which will serve as housing for all electronic components, the external sensors, the timing crystal, and the battery. The receiver circuit was prototyped on a 0.5-mum complementary metal-oxide-semiconductor (CMOS) chip. Extensive lab tests proved all system component functional. The fully operational receiver consumes 21 muW at 3 V. Results from a preliminary field test, conducted with a source generating a sound pressure level of 180 dB re 1 muPa, predict a tracking range of 100-120 km