Abstract: A circuit arrangement for comparing a clock pulse train against a standard pulse train. The circuit includes an exclusive OR gate to which are inputted the pulse train to be tested, and a latch at the output of the gate, operated only upon a mismatch of the two pulse trains. Provision is also made to prevent operation of the latch within certain adjustable tolerance parameters as to pulse width and position of the pulse train.

Abstract: An arbitration controller providing for equal priority sharing of duplicate copy resources by a duplex plurality of central processing units. Conflicts resulting from simultaneous requests from several CPU's for access to the common resource are resolved at a high rate of speed. In addition, an approximately statistically equal probability is maintained for access of the common resource by all the central processing units.

Abstract: An active circuit for modeling desireable diode and varistor characteristics in signal limiting circuits. The circuit includes a resistor arrangement for setting the desireable threshold voltage to an operational amplifier, the other input of which is connected to a reference voltage level. The amplifier output is tied back to the circuit input and to one input of a second amplifier. A second input is connected to the reference voltage level to act as a current sensor to vary the threshold level in response to the current flow.

Abstract: A momentary contact actuator and designation cap assembly designed to be used with a single switch of a laminated flat-panel keyboard. The assembly consists of a housing which snaps over the flat-panel switch, a cantilivered actuator located within the interior of the housing, a designation insert installed over the actuator including switch identification printed thereon, and a transparent cover installed over the insert. Manual pressure applied to the actuator operates the associated flat-panel switch.

Abstract: Apparatus for field measurement of the insertion loss of a splice between one ends of first and second optical fibers comprises an integrating sphere that is split along its axis and which has a fiber input port, a pair of spaced-apart padded holes on the axis for receiving associated fibers so as to center the splice inside the sphere, and an output port receiving one end of a fiber bundle which couples diffuse light in the sphere to a radiometer. A baffle plate in the sphere prevents light rays from the splice being incident on the output port. The splice loss is determined by inserting the one end of the first fiber into the input port, with the other end illuminated by light from a source, and reading a reference level of light coupled to the radiometer. The two fibers are then spliced together and the splice located inside the sphere.

Abstract: This is a circuit for use to increase the number of bus circuit boards in a closed loop bus configuration. This circuit detects which bus circuit board is the last circuit board equipped in a closed loop configuration and closes the bus at that circuit, without requiring wiring changes or "dummy" circuit boards.

Abstract: A circuit which can perform a plurality of sensor functions relating to telephone subscriber supervisory circuits. These functions can occur before and after ringing current is applied to the subscriber line facility. Coils function as magnetic field generating devices and a Hall effect device is used to perform the sensory functions. A programmable comparator is used to compare detected conditions with predetermined thresholds.

Abstract: A wall telephone cradle assembly comprised of a housing having a cup shaped pocket on a front face thereof, arranged to hold a hand-held telephone instrument therein. Mounting structures located within the housing are disposed to mount the assembly to a two pin wall telephone receptacle plate.

Abstract: A circuit which detects specific pulses superimposed on noise and other pulse signals. Threshold detecting comparators are used to discriminate between class of service pulses, noise pulses and other supervisory signals.

Abstract: A momentary contact actuator and identification cap assembly disposed to be used with a single switch of a laminated flat-panel keyboard. The assembly consists of a clear cap component which snaps over a flat-panel switch, an identification insert, and a tension bar including spring arms situated within the interior of the clear cap. The spring arms hold the assembly suspended over the associated flat-panel switch. Manual pressure applied to the clear cap deflects the assembly operating the flat-panel switch.

Abstract: A system is shown for automatically detecting the integrity of telephone subscriber's line connection to a four wire switching system via a hybrid network.

Abstract: A circuit which monitors a coin telephone for coin ground, coin collect, coin return, stuck coin and ground fault conditions. Hall effect devices are used to detect the status of these conditions and to provide isolation between the coin telephone line and the coin telephone monitor circuit.

Abstract: An electromagnetic device utilizing a pair of Hall effect switches for detecting the presence or absence of an electrical current of a first and a second value. The device includes a flux generator for generating a field of magnetic flux and a magnetic circuit including a pair of adjustable cores for varying the amount of flux delivered to the Hall switches. A first Hall switch outputs a signal responsive to the presence or absence of a current of a first value and the second a signal representative of a current of a second value.