Abstract: An automatic protection and recovery method for a telephone line interface circuit is described. The interface circuit monitors current on the line, and in the event of a fault producing an excessive current a protection relay interrupts a connection of the interface circuit to the line, and the interface circuit monitors common mode voltage on the line. The interface circuit is reconnected in response to the monitored voltage being below a relatively high threshold. If a second interruption results, the interface circuit is then reconnected in response to the monitored voltage being below a lower threshold. If a further interruption results, the interface circuit enters a ground fault recovery process. The method facilitates protection and rapid recovery from arbitrary fault conditions on the telephone line.

Abstract: A remotely controlled telephone system terminal box provides non-blocking connectivity between any selected unassigned pair of a plurality X of distribution pairs of lines and any selected plurality Y of drop pairs of lines and employs a plurality X of multiple-position rotary stepper switch blocks each driven by a stepper motor, the stepper switch blocks being selectively actuated by commands from a remotely located central office controller. A continuity test circuit within each of the terminal boxes is responsive to commands from the central office controller for verifying that electrical contact is made between an associated one of the plurality X of distribution pairs of lines and a selected one of the plurality Y of drop pairs of lines. A control pair contention circuit within each of the terminal boxes allows a plurality of the terminal boxes forming a distribution network to be controlled by a single control pair of lines coupling all of the terminal boxes to the central office controller.

Abstract: A data communication system comprises two links between two terminal equipments, a standby link being used in the event of malfunctioning of a normal link. A method of returning to the normal link after using the standby link comprises, in parallel with transmission on the standby link, preliminary verification of the continuity of the normal link. The preliminary verification involves simultaneous transmission of a data signal by the terminal equipment initiating the continuity verification procedure, on the normal link and on the standby link, and detection by the other terminal equipment of the presence or absence of power on the normal link. This is done for each transmission medium of the normal link if the latter comprises separate media for each transmission direction.

Abstract: In order to back up by an ISDN line two analog lines connected to MODEM of a four wire full duplex type for data transmission and reception, a terminal adapter is connected to a pair of back-up ports. Dial pulse signals delivered through the back-up ports are detected and converted into an ISDN telephone number. A D-channel processor performs the call connection by use of the D-channel signal having the ISDN telephone number and an identifier of a particular one of B-channels. An outgoing analog data from the MODEM through one of the back-up ports is A/D converted and then transmitted on the particular B-channel to the ISDN line. An incoming digital data on the particular B-channel signal received at the terminal adapter is D/A converted and is supplied to the MODEM through the other of the back-up ports. Thus, the back-up is performed by use of a single B-channel on the ISDN line.

Abstract: This failure management system architecture guides, detects, validates and logs field replaceable unit (FRU) changes. This system includes a guided capability by which service personnel use the guided process to select candidates for FRU swaps or FRU replacement. FRU change and swap detection is described as a function of FRU memory scanning coupled with embedded database query activity. For swap activity virtual Composite Failure Events are created to manage post-swap failures. Validation logic determines whether the changed FRU is positioned correctly, is at the correct hardware, software and feature level, executes diagnostics correctly and performs flawlessly during monitored and extended functional operation.

Abstract: A ring communications network having a plurality of line concentrators (10) each including a ring-in port (16), a ring-out port (18), and a plurality of station ports (20), includes the feature of being able to detect a fault in the trunk cable between concentrators and reconfiguring the ring to bypass that fault. Fault detection is accomplished by injecting a phantom DC voltage at the ring-out port and sensing whether current due to that voltage is present at both the ring-out port and the ring-in port of the next adjacent concentrator in the ring.

Abstract: A telephone system comprises a multi-channel transmission apparatus for connecting a subscriber line to a telephone exchanger, where the transmission apparatus comprises: a subscriber interface for interfacing said subscriber line; a detecting circuit in the subscriber interface for detecting a change in a voltage on the subscriber line; and a discriminating circuit for discriminating whether the change detected by the detecting circuit is continuous or intermittent, upon discriminating the detected change in voltage as intermittent the discriminating circuit outputs a first alarm signal. The discriminating circuit may be formed of a software counter which counts a number of the intermittent signals for a predetermined period. The software counter does not require a bulky and expensive components, such as a 60 Hz filter. If the counted number is larger than a predetermined number the signal is determined to be intermittent.

Abstract: The present invention provides an approach to reconnect a communications network such as a DS3 telephone-type network when a span of DS3 channels is rendered inoperative, such as by cutting, within the 1.5 second time frame necessary to prevent disablement of local offices. This is accomplished by preplanning a restoration connection for each possible operating link failure in each span using spare capacity. A dedicated (DS3) communication loop is used to inform all nodes in the network substantially simultaneously to implement their portion of a plan associated with the failed span. After the restoration occurs for a given failed span, the concept can be extended to start planning for further failures or can be designed to restore further failures on a real time basis.

Abstract: A digital telephone set includes a digital telephone circuit and an emergency analog circuit. Normally, the digital telephone circuit is made active so that a handset provided in common therewith is connected to a digital transmission line. In an emergency, the emergency analog circuit is made active instead of the digital telephone circuit so that the handset is connected to an analog transmission line. A dial key pad unit and a speaker are provided in common with the digital telephone circuit and the emergency analog circuit.

Abstract: A one-to-one line switching system for switching between a hot line and a standby line in a one-to-one correspondence. To enable removal of a switching unit while in use, from a mother board for change over or repair, a pair of switching units (1 and 2 or 3 and 4) is provided at the transmitting part and at the receiving part, respectively, the earth element in one of the pair being connected to the other of the pair and the other of the pair being pulled up by a voltage, whereby, when one of the pair in use is removed, the other of the pair can pass the input signal.

Abstract: A modem use monitor (MUM) is disclosed which is utilizable with one or more groups of modems for analyzing modem defects of the individual modems. Typically, a rotary hunt arrangement of telephone lines for data communications is sequentially served by several modems. For analytical purposes, an intercept device is provided to receive a data carrier detect signal from each modem. The intercept device has been enhanced to receive a plurality of signals and to facilitate defect analysis. Exemplary of the processed signals is the summing of the ring indicator (RI) signal and the data carrier detect (DCD) by means of a logical OR to provide a single test signal which can be examined for a ring-no-answer condition.

Abstract: The functionality of the SMSI protocol is extended by adding to the SMSI protocol messages having the same format as the conventional SMSI protocol messages but implementing leave word calling functions for a voice message system adjunct processor and integrating maintenance functions of an adjunct processor and an SMSI protocol-to-non-SMSI protocol converter.

Abstract: The functionality of the SMSI protocol is extended by adding to the SMSI protocol messages having the same format as the conventional SMSI protocol messages but implementing leave word calling functions for a voice message system adjunct processor and integrating maintenance functions of an adjunct processor and an SMSI protocol-to-non-SMSI protocol converter.

Abstract: A digital bypass unit for a PBX or ACD telephone system having T1 spans provides the capability to place and answer calls on a digital T1 span in the event of a system failure or power failure. The bypass unit permits the bypass of the failed system, connecting T1 channels directly to digital telephone sets, and is automatically activated in the event of power or system failure. Queueing and distribution of incoming calls are both provided when the system is in the bypass mode.

Abstract: A fail safe voice system and method for digital telephone networks. The system provides for operation of voice telephone equipment at a customer location when a fault occurs at the customer location. The system has a central office with an analog line termination/digital transceiver connected to subscriber loop lines. The customer location has a digital transceiver/analog station set interface connected to the subscriber loop lines and to the voice telephone equipment. In response to a fault at the customer location the voice telephone equipment is connected directly to the subscriber loop lines thereby eliminating the digital transceiver/analog station set interface.

Abstract: A method and apparatus for detecting and analyzing errors in a communications system is described. The method employs expert system techniques to isolate failures to specific field replaceable units and attempts to restore the failing unit to service, if the system will not be adversely affected, by removing it from service, resetting the resource and returning it to service if it passes retesting. The expert system techniques include detailed decision trees designed for each resource in the system. The decision trees also filter extraneous sources of errors from affecting the error analysis results.

Abstract: A transmission line between terminals of a three-terminal station is branched by a branching unit and power is transmitted between the terminals of the three-terminal station and a power feed system in the transmission line including: a switch for switching a power feed line feeding power to a repeater between a both-end power feed mode and a single-end power feed mode; and connection holding means for holding a power feed connection state without change upon an occurrence of a failure.

Abstract: A circuit arrangement is disclosed by which one of two subscribers (T1, T2) can be connected to a subscriber line (ASL) of the public telecommunication network if a device (2) associated with both subscribers (T1, T2) experiences trouble. The two subscribers (T1, T2) are, in normal operation, both connected to the subscriber line (ASL). Transmission of the signals takes place in this case between the device (2) and an office of the telecommunication network digitally over the subscriber line (ASL). In the event of a disturbance, one subscriber (T1) can be connected by a bypass line (8) to the office with analog signal transfer.

Abstract: A test system for microwave circuits such as employed in aircraft wherein a plurality of antennas are connected to a single processor whereby the continuity of the antennas and connectors between the antennas and the processor can be determined. A test signal is applied to the various antennae of the aircraft and the return signals therefrom received by a test antenna disposed in conjunction with a low-loss coupler from outside of the aircraft. An automated test circuit provides for inputting an identifier of the antenna and circuit portion being tested, and for determining the fault location within the circuit as a function of the circuit portion under test and the distance to the fault; and for displaying the fault location within the circuit. In one embodiment, the low-loss coupler includes the use of a plurality of test antennas in combination with a divider circuit connected to the test antennas by transmission lines.

Abstract: A remote unit monitoring system is provided which monitors any number of hazard conditions in an electrical substation and transmits this information via telephone lines and radio link to a central station. The system automatically dials the central station, after checking the integrity of each communications channel. Data is transferred only after a kissoff signal is received from the central station indicating that the communication channel is secure. The substation continues transmitting the data until the data accuracy is verified by the central station. Battery backup of all critical circuits is provided as well as visual indications of any failure in the system. The central station is provided with the ability to query the substation at any time.

Abstract: The equipment consists of one or more voice units (U1 . . . Un) each connected to a certain number of independent lines (E1 . . . En) connected to a telephone network (RT). Each unit presents an announcement data base (AA1 . . . AAn) which contains all possible announcements to be supplied to the subscribers, a computer (EL1 . . . ELn) which manages the research of an announcement in the data base (AA1 . . . AAn) and its sending to the subscribers (UT1 . . . UTx) and an interface (IEC1 . . . IECn) towards the network (RT) for the temporary storage of the announcements or part of them before the sending, the processing of the telephone signalling, the possible conversion into analog form, and the equipment supervision.

Abstract: Apparatus for connecting in series a plurality of communication line pairs, typically direct connected security loops used by alarm companies for monitoring customer's facilities. A bridge with pairs of bridge terminals and switches for connecting bridge terminal pairs to communication line pairs or to terminating lines. Local and remote control for the switches and control apparatus which permits service personnel to selectively terminate a bridge terminal pair with a direct or zero resistance connection line and leave a subscriber's communication line open, for maintaining service for other communication lines connected to the bridge while performing maintenance on the disconnected line. The apparatus is suitable for bridges with various numbers of terminals, such as six way, eight way and twelve way.