Abstract: A magnetostrictive liquid level transducer equipped with a number of temperature sensitive resistors is supplied with low level power from a remote station and charges a capacitor to store power for interrogation of the level transducer. The transducer is interrogated periodically for level measurements and the capacitor is recharged between interrogations. During the recharging periods, temperature measurements are made. Thus the level and temperature related data is measured and transmitted alternately. Each measurement results in a pair of pulses having a spacing corresponding to the measured value. The transmission message comprises a plurality of frames or time periods. The first frame is blank and is used for synchronizing the receiving device with the message frames. The subsequent frames have the level and temperature related data interleaved in the message and are easily sorted by the receiving device at the remote station. The data pulses are sent on the power transmission conductors.

Abstract: A damped sine wave detector for detecting the response of a magnetostrictive displacement transducer. A pretrigger comparator compares the signal to a predetermined negative threshold. A signal comparator compares the input signal to a predetermined positive threshold. The pretrigger comparator turns on a pretrigger flip-flop and starts a delay timer when the input signal falls below the predetermined negative threshold. The pretrigger flip-flop supplies the data input of a signal flip-flop. The signal flip-flop is clocked by the signal comparator when the input signal is above the predetermined positive threshold. The signal flip-flop turns on if clocked and the pretrigger flip-flop is on. The detector includes two timers for resetting the flip-flops. An inhibit timer resets both flip-flops upon expiration of an inhibit time longer than the maximum expected duration of the damped sine wave signal.