Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or the repeater, or for retransmitting test pulses on the next cable to the next repeater for causing it it perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: A power distribution system that provides supervision and protection. Hall effect devices are used to monitor power from a central power supply to a plurality of power converters. Fuses are connected between the converters and the central power source to protect the converters from catastrophic failure. Hall effect devices also monitor the output of power from the converters. A current controlling inductor is included between the converter outputs and the output power bus in order to restrict reverse current flow from a time that is sufficient to allow a circuit breaker to disconnect a failed converter. The Hall effect devices are connected to a computer which monitors the power in and out of the converters. The computer is thus able to detect a failed converter and disconnects it by operating an associated circuit breaker.

Abstract: This circuit provides a scheme for protecting a common dynamic memory of a distributed processing system. This circuit protects against premature completion of a memory access cycle by a CPU for any of a number of fault conditions. As a result, common memory integrity is maintained despite a high number of memory accesses by a number of CPUs. This circuit operates in a simplex configuration or a duplicated redundant configuration.

Abstract: A circuit terminating device for mechanically retaining and electrically connecting a planar substrate such as a thick/thin film circuit to a printed wiring card. The terminating device is characterized by a terminating body having planar sidewalls defining a hollow interconnection post receiving area therebetween. A pair of substrate spring members extend from a sidewall of the terminating body arranged to compressively accept an edge of the substrate retaining and connecting the substrate to the terminating body. Post spring members extending inwardly into the post receiving area engage an interconnection post which extends from the printed wiring card thereby retaining the terminating body to the printed wiring card.

Abstract: A control circuit which monitors the output voltage of multiple power supplies connected to each other in a diode-or arrangement. When one power supply provides a higher voltage than the others the control circuit causes the lower output power supplies to operate in a standby mode. The control circuit includes voltage dividers on both sides of the output diode of the power supplies. These voltage dividers provide indications of the voltage output of their associated power supply and the other power supplies. A voltage comparator monitors the output voltage of its associated power supply and the other diode-or connected power supplies as indicated by the voltage dividers. The voltage comparator to adjust the voltage output of the associated power supply to a level just below the high output power supply, thereby leaving it in a standby mode of operation.

Abstract: A digital multifrequency receiver circuit of the type employed between telephone system central offices, arranged to provide a faster response to received signals by processing the received signal tones digitally. The faster response resulting from the elimination of automatic gain control circuits and the use of a fixed gain amplifier used only when the received signal is below an acceptable level and the provision of a variable threshold to the individual frequency comparator circuits.

Abstract: An electrical circuit functioning as a temperature sensor which is fully compatible with silicon chip and similar integrated circuit technology. Four matched NPN bi-polar transistors provide a circuit that detects changes in temperature by monitoring the current throughput in operation. Environmental temperatures increase current approximately one order of magnitude for each 25 degrees centigrade of changing temperature. With a current gain of 100 for each transistor employed, the current increases from 0.1 microamp at 0 degrees centigrade to 11 microamps at 50 degrees centigrade.

Abstract: A snubber circuit for use with hold circuits employed in telecommunication applications that employ an SCR as the principle control device. The included circuit prevents false hold turn on in response to static discharge. Voice band impedance and ringing signals are not adversely affected by the addition of the circuit to a standard SCR type hold circuit.

Abstract: A bidirectional word length converter for use in transferring data between a first data processing unit and second data processing unit each using a word format of a different length. The converter includes a buffer connected between the first and second units and a converter control. The converter control is adapted to accept a plurality of mode signals from the first unit to control the transfer of data in a first length word format from the first unit to the second unit in a second length word format. The converter control is further adapted to accept an alternative plurality of mode signals to transfer data from the second unit to the first unit in a similar manner.

Abstract: A support for a vertically oriented equipment drawer including a plurality of guide rollers and a band roller attached to a lower edge thereof, the guide roller riding in a lower guide track positioned on a supporting equipment floor and the band roller rolling on a band of flexible material layed out in the path of the roller as the equipment drawer is withdrawn from an equipment frame. A tensile force is applied to the band to take up slack and optionally to exert a force on the band roller to permit the equipment drawer to automatically retract back into the equipment frame. A latch is included to engage the band when the equipment drawer is in a withdrawn position to prevent automatic retraction of the equipment drawer. Flat guide rollers engaging an upper guide track are attached to an upper edge of the equipment drawer to prevent lateral movement thereof.

Abstract: The DTMF receiver sense and control arrangement collects and stores multiple customer originated data for determination of customer identification, validity and billing purposes. This arrangement is part of a telecommunications switching office and monitors up to 24 DTMF receivers (channels) to determine whether each channel contains valid data. This data is stored in temporary storage for subsequent transmission to a processor of the switching office. Each of the DTMF receivers asynchronously presents data for collection by this arrangement. This arrangement provides the proper timing required to operate up to 24 receivers to obtain their data, while it is stable at the receiver. Once a receiver transmits data, this arrangement then synchronizes its operation to that receiver so that, sequential monitoring of each of the 24 channels is guaranteed and no loss of valid data will result. In addition, each DTMF receiver may be enabled selectively for special monitoring.

Abstract: A binary synchronous bit-sliced counter comprising a plurality of cascaded identical stages (slices). Each stage only requires for its operation a source of potential V.sub.dd, a carry-in signal input line, a clock signal input line, a reset signal input line and a carry-out signal output line. Cascading of the slices is implemented by connecting the carry-out signal output line of one slice to the carry-in signal input line of another slice and connecting the clock signal and reset signal input lines to all cascaded stages in parallel.

Abstract: A clamp for cables passing through a panel near an edge thereof including an anvil, a clamping pad and a latch member all positioned on a slideable basis within a slot extending from an edge of the panel inward a predetermined distance. Slots in the anvil interferingly engage and hold cables therein to facilitate assembly of the clamp. Fingers extending from arms of the latch member engage catches in side edges of the slot to lock the latch member in compressive engagement with the pad thereby clamping the cables between the anvil and the pad.

Abstract: A retainer for printed wiring boards mounted in a file including an open front face through which the printed wiring boards are inserted. A plurality of clips are clipped to a front support bar supporting a lower edge of the printed wiring boards and extending between a front end of a pair of support arms. The clips are arranged for sliding nonrotational movement along the support bar and each includes a retainer slot in which a retainer bar is positioned to engage a front edge of each of the printed wiring boards thereby to prevent their removal. Each clip includes a cavity which may be slid into engagement with a foot portion of the retainer bar to lock the bar in position and prevent unintentional dislodging of the retainer bar.

Abstract: An adaptor base for a telephone instrument that facilitates the instrument's use in both desk and wall mounted modes. Simplified construction allows the telephone user to reposition the base from one position to another, and even back to the first position if desired. The adaptor base is also so designed that the base and associated telephone can be mounted on a standard jack for a wall mounted telephone.

Abstract: A secretarial telephone station for use with a secretarial answering system and a switching system which includes a plurality of subscriber telephone stations each equipped with a buzzer. The secretarial answering system is connected to the subscriber stations and transmits subscriber station busy, idle and ringing status and line identification information to the secretarial station. The secretarial station includes a lamp and switch pair for each associated subscriber station, first and second processing units, and an audible signalling circuit. The first processing unit receives this information according to a link bus protocol for packetized messages. The second processing unit receives this information and causes the lamp associated with each of the subscriber stations to display dark, lit or flashing signals corresponding to the idle, busy and ringing status. The second processing unit also causes the audible signalling circuit to provide a ringing tone whenever a lamp is flashed.

Abstract: A precise temperature dependent voltage reference and voltage comparator comprising a three terminal circuit. When the input voltage exceeds a predetermined threshold, the output switches from the nonconducting, "off" state to a current conducting "on" state. The threshold condition can be tailored to a specific temperature characteristic and low voltage range with an input current on the order of 25 microamperes. With the output tied to the input, the circuitry can act as a reference diode.

Abstract: This invention is a cost efficient method for controlling a multistage space switching network for high voltage applications. This method minimizes the number of control signal leads required to operate a multistage space switching network. If a switching network has N space switching stages, then the present invention provides for performing the space switching function with N+1 control signal leads. The present space switching method may also be employed for conventional non-high voltage space switching applications.

Abstract: A circuit which prevents a telephone station from being used for unauthorized toll calls while allowing toll calls to be made when preceded by authorized passwords. When the telephone station is in the toll restriction mode of operation a microprocessor disconnects the tone generator from the keypad and provides audible and visual error signals upon detection of operation of the "0" or "1" keypad buttons. Upon detection of simultaneous operation of the "1" and "2" keypad buttons, the microprocessor provides audible and visual signals to prompt entry of a password. If a valid password is entered, the telephone station enters the unrestricted mode of operation and the toll restriction circuit is disabled until the handset is returned to the on-hook position after termination of the subsequent toll call.

Abstract: This invention is a cost efficient network arrangement for a space switching network for high voltage applications. This arrangement minimizes the number of control signal leads for a multistage switching network. If a switching network has N stages, then the present invention provides for performing the space switching operation with N+1 control signal leads. The present space switch arrangement may also be employed for conventional non-high voltage space switching applications.