Abstract: A control system for controlling a variable of a device by an end element is disclosed. The control system has as its input a magnetostrictive position sensing probe for measuring the value of the variable of the device at time intervals and a digital controller reading the value from the magnetostrictive position sensing probe and having an output and means for calculating control output from the updated value of the variable during the time interval. The digital controller is close coupled to the magnetostrictive position sensing probe to permit time intervals that are very short, such as 500 microseconds to 1 millisecond.

Abstract: A telephone call monitoring apparatus is described for monitoring a subscriber's telephone to determine the time of day in which incoming or outgoing telephone calls are made and the duration of the calls. Additionally the apparatus determines and records the telephone number of the "called" telephone. The apparatus is responsive to the frequency, duration and pause between ring back signals placed on the telephone to determine the estimated time that the call is answered by the called telephone.

Abstract: A linearly movable irrigation system, according to the present invention, may include a plurality of interconnected power driven irrigation spans supporting a water supply conduit, which sections are capable of moving over a land area and depositing a controlled amount of water thereon. At one extremity of the irrigation system may be provided a steerable and powered mover unit that accepts water from a water supply system and conducts it to the overhead irrigation pipe under sufficient pressure to cause proper distribution of water through sprinkler devices located along the length of the irrigation conduit. A power driven pump may be supported by the steerable mover unit in order to pressurize or provide boosting pressure for the water received from the water supply. The steerable mover unit is adapted to steerably move in proximity to an elongated reference which may be straight or curved as desired.