Abstract: An uncomplicated and reliable temperature sensor has a pair thermistors coupled in parallel with a current source that is connected in series with a load resistor. Temperature variations cause a robust current output change that generates a corresponding robust output voltage determined by a proper selection of the load resistor. Increased sensitivity is provided by the robust current to avoid many of the problems otherwise associated with D.C. amplifiers (e.g., drift).

Abstract: This invention is an apparatus and method created around a specialized micomputer attachable to and addressable to each thermister in an array of thermisters used to measure temperature in the sea. The invention provides a number of options so that the same model of microcomputer can be adapted to several different modes of operation and used to monitor a variety of other sensors that have electrical resistance, voltage or current as outputs. Alternate modes of operation for resistive sensors are presented where a number that fixes the measurement as a fraction of the dynamic range of the variable being measured is determined. The system includes the circuits and memory needed to adapt it to any of a variety of sensors measuring physical quantities.

Abstract: An apparatus hydromechanically decouples a hydrophone arrangement disposed n a water medium from the effects of current, wind and surface wave action. A first float carrying a transmitter-antenna assembly extends through the water-air interface and is tethered to an auxiliary float which buoyantly supports the hydrophone arrangement. A line, hundreds or thousands of feet long, is suspended by the auxiliary float and terminates in a sonobuoy tube at a predetermined depth. From the tube the hydrophone arrangement and a high pressure float are pulled out by a weighted nose portion. After the hydrophone arrangement, high pressure float and a length of line are pulled from the tube, a weak link between the hydrophone arrangement and nose portion snaps allowing the weighted nose to sink. The high pressure float has sufficient buoyancy to support the hydrophone arrangement and a portion of the length of line causing it to assume a cantenary configuration.

Abstract: Calibration of expendable sonobuoys can be made in-situ to assure the transmission of representative data. A pair of integrated circuit timers are coupled together to provide on-off duty cycles during which a spectral distribution of calibration signals is fed to the sonobuoy. Since the spectral distribution and amplitude of the calibration signals are known, a remote monitoring station is continuously apprised of the sonobuoy's calibration.