Abstract: In a program-controlled telecommunication system (KS), at least sub-areas (SLM1..n) are controlled into an energy-saving mode with reduced energy consumption using a central controller (ZS) and additional controllers (SM) given the presence of energy-saving information (ei). The energy-saving information (ei) are formed, for example, using a timer (UM) in the telecommunication system (KS) and using an implemented energy-saving routine (ESR). A telecommunication system (KS) fashioned in this way can be controlled into an energy-saving mode, for example during the night or over weekends.

Abstract: A power-conserving, loop start signalling, dual-voltage line-feed circuit that maintains ac longitudinal balance on the loop conductors and which limits average and peak loop current not only when the loop is in the off-hook transmission state but also during part-time on-hook transmission. The current-limiting circuitry employs feedback so that a virtual ground is presented toward the line feed transformer at voice frequencies to reduce battery noise and potential crosstalk that might otherwise couple into the circuit because of non-zero battery impedance. The circuit provides for injecting a voltage-controlled feed current into the current regulator to maintain sufficient drive current so the current regulator can continue to maintain the virtual ground when the loop is on hook.

Abstract: A telephony system includes a plurality of local network terminations connected to a street cabinet in turn connected to an exchange. The street cabinet has a power supply for supplying voltage, a clock for generating a master ringer signal, and a modulator for modulating the voltage with the ringer signal. The filters extract the DC voltage and the ringer signal. The extracted DC voltage and the extracted ringer signal obviate the prior art requirements to provide a separate DC power supply and a separate clock within each local network termination, thereby avoiding duplication of components within each local network termination.

Abstract: Resistive circuits are provided at the tip and ring of the battery feed circuit as a method of alleviating the need for bulky DC transformers or complex integrated circuitry. The voltage is monitored through a set of comparators eliminating the expense of maintaining fused resistors. The voltages for voice or data transmission is amplified prior to being transmitted. Received signals are AC coupled, with proper biasing, onto the tip and ring lines. Any AC noise on the tip and ring line is shifted 180 degrees out of phase and re-inserted on the line to cancel the noise. As an enhancement to the battery feed circuit, another voltage comparator is added to check the line for DC current signifying an off hook condition.

Abstract: An improved network interface unit having a substantially smaller width than many prior art network interface units. The network interface unit comprises a single, planar circuit board assembly interconnected between incoming and outgoing telephone lines and incoming and outgoing customer premises lines. Two relays and a controller are mounted on the board. The controller monitors the transmission of data along the lines and, by activating the relays, provides communication and maintenance functions, such as loopback. The network interface unit utilizes a controller made up of (1) a processor-based software control system and (2) an integrally cooperating application specific integrated circuit. The controller may, for example, provide and monitor framing, detect and monitor signals, and convert bipolar data to unipolar data.

Abstract: A telephone and auxiliary power distribution system includes an optical fiber in joint combination with one or more copper conductors to provide electric power for powering the various electronic devices associated with the optical fiber telephone distribution system.

Abstract: A circuit for limiting power dissipation through telephone subscriber line power supply interface devices, by using a pair of final stages to which an external component effective to dissipate power is connected. By use of separate discrete reference circuits, the presence of excessive common mode current is detected; and when this occurs, current to the driver stages is controlled at a lower magnitude.

Abstract: In a digital data communications device for use in an ISDN environment, a power supply apparatus and method are provided for energizing telephone danger circuitry or other alerting mechanisms. Embodiments of the present invention employ signal generators which control switching circuitry that converts a low voltage DC power source into a low voltage alternating current. A step-up transformer is used to convert or transform this low voltage into a high voltage alternating current, which is rectified and filtered to generate a high voltage direct current. The signal generators also control the switching circuitry which applies this high voltage direct current to an alerting mechanism and alternately provides a path to discharge energy which may be stored in the alerting mechanism, causing the alerting mechanism or other ringer circuitry to resound.

Abstract: In a telecommunication unit attached to a telephone line, power is provided by taking power from the telephone line when the unit is off-hook. When the unit remains on-hook, power is maintained to circuitry in the unit by a charge stored in a capacitor. When the capacitor's charge is reduced to a level no longer able to sustain operation of the unit, the unit is briefly taken off-hook, allowing the capacitor to recharge. Charge control of the capacitor is performed either by discrete circuitry or by a microcontroller, and further includes logic provisions preventing the unit from remaining off-hook for an unduly long period of time.

Abstract: An improved network interface unit having a substantially smaller width than many prior art network interface units. The network interface unit comprises a single, planar circuit board assembly interconnected between incoming and outgoing telephone lines and incoming and outgoing customer premises lines. Two relays and a controller are mounted on the board. The controller monitors the transmission of data along the lines and, by activating the relays, provides communication and maintenance functions, such as loopback. The network interface unit utilizes a controller made up of (1) a processor-based software control system and (2) an integrally cooperating application specific integrated circuit. The controller may, for example, provide and monitor framing, detect and monitor signals, and convert bipolar data to unipolar data.

Abstract: A circuit is provided in telecommunication terminal equipment for splitting a limited supply of current received from a subscriber's line current among a plurality of functional circuits according to their priority rank. The circuit uses a differential pair of current delivering transistors and a special circuit to monitor the actual current of absorption of at least the functional circuit of highest rank to produce a control signal that is used for modifying the drive conditions of the current delivering transistors. All current exceeding the actual absorption needs of the highest rank functional circuit is distributed to the other functional circuits and the prior art practice of sinking unneeded current through a dissipative shunt voltage regulator associated with each functional circuit is avoided. This same principle may be advantageously applied also to functional circuits of progressively lesser rank of priority.

Abstract: The arrangement is such that to a transmission apparatus of the subscriber side in a subscriber transmission system wherein the transmission apparatus of the subscriber side which serves a plurality of subscribers and a transmission apparatus connected to a switching system are connected to each other via multiplexed transmission lines, there are provided memories to store originating and terminating call signals, and a controller not only to control so that only subscriber transmitter-receivers corresponding to a specific number of subscribers in the subscriber transmitter-receivers for transmitting and receiving signals of subscribers enter an operating state, but also to cause the memories to operate, so that electric power is supplied only to circuits corresponding to a specific number of subscribers in the transmission apparatus of the subscriber side by controlling through the controller when the rate of telephone use is low.

Abstract: A call detection control apparatus includes individual call detecting circuits, a common call detecting circuit, switching circuits, and a power supply circuit. The individual call detecting circuits individually detect call signals, which originate from telephone subscriber lines. The common call detecting circuit commonly detects call signals, which originate from the respective telephone subscriber lines. The switching circuits switch the respective telephone subscriber lines from the common call detecting circuit to the respective individual call detecting circuit when the common call detecting circuit detects an call signal from one of the respective telephone subscriber lines. The power supply circuit supplies operating power to each of the individual call detecting circuits upon interlocking with an operation of a corresponding one of the switching circuits.

Abstract: A supply circuit for a two-wire telecommunication line includes a voltage adjusting circuit section coupled between one of the wires and a first reference potential point and further includes a current source coupled between the second wire and a second reference potential point. A transistor in the voltage adjusting circuit section has a first main electrode coupled to the first wire, a second main electrode coupled to the first reference potential point, and a control electrode which is coupled to the first wire by way of a capacitor. In order for the supply circuit to meet strict requirements as to symmetry and demodulation, the control electrode is also coupled to the first reference potential point by way of a threshold voltage diode, which may be a zener diode. A voltage control circuit coupled to the threshold voltage diode forms a feedback loop for maintaining the line voltage at a selected value despite the presence of disturbing signals on the line.

Abstract: A battery feed circuit supplies a feed current to a telephone set via a 2-wire telecommunication line formed of a TIP line and a RING line.

Abstract: A circuit is described which comprises an operational amplifier, two resistors connected between the telephone line and the inputs of the amplifier, a capacitor which is charged via a first bipolar transistor controlled by the amplifier via a first FET transistor, a second bipolar transistor in parallel to the connection of the first transistor and the capacitor, a second FET transistor, identical to the first and having its source and gate terminals connected to the corresponding terminals of the first, and two current generators connected to the drain terminals respectively of the first and the second FET transistor and to the bases, respectively, of the first and second bipolar transistor.

Abstract: A two-wire telephone line interface circuit comprises a driver circuit for supplying direct current on the line, a controlled voltage generator, a sensing circuit for monitoring the line current, a control circuit for controlling an output voltage of the voltage generator, and a switching circuit. The control circuit controls the switching circuit to supply, as a supply voltage for the driver circuit, a battery voltage in an on-hook state of the line or the controlled output voltage of the voltage generator in an off-hook state of the line, this output voltage being controlled to provide off-hook current limiting. The control circuit also controls the switching circuit to selectively supply the controlled output voltage of the voltage generator as a signalling voltage to at least one wire of the line for high voltage signalling, e.g. ringing, on the line. Desirable forms of the switching circuit are described.

Abstract: An electronic interface circuit between a telephone subscriber line and a telephone main exchange is disclosed which forms, with the main exchange battery, a supply bridge for the telephone line, with limitation of the line current to a predetermined threshold value. The voltage/current characteristic of the supply bridge is balanced for lower values of the line current than the threshold current and is unbalanced whenever the line current attains said threshold current.

Abstract: A DC to DC power converter in the form of a pulse-width modulator is shown which can sense via an indication of duty cycle how much reserve power is available for loads using the present input voltage. The device is for use at the end of a telephone line where the input voltage power supply impedance can be appreciable. When the reserve power, as detected in the power converter, reaches a minimum critical level, a signal is sent out requesting the voltage supply to increase the available voltage to the power converter.

Abstract: A sealing current generator for a telephone circuit provides a conventional nominal DC bias current in a telephone loop, and also temporarily provides a higher "zap" current whenever the DC current path is broken and then reapplied to the telephone loop. During the "zap" period, the voltage placed across the telephone loop is progressively increased in a number of predetermined steps if the current actually measured in the telephone loop fails to exceed a minimum value. The voltage is then maintained at its last level for the remainder of the "zap" period, after which the device returns to its base mode of providing a nominal DC bias current to the telephone loop.

Abstract: In a ground fault detector for long distance subscriber lines accommodated in a small capacity digital electronic exchange, a DC/DC converter for power supply is stopped during detection of ground fault. Upon reception of the stop signal, the DC/DC converter converts the power supply voltage for the subscribers to a voltage as the system power supply of the exchange, namely to a low voltage before voltage conversion of the DC/DC converter. The battery feed circuit can maintain the alarm condition, even if a current flows continuously to the battery feed resistor due to a ground fault, until the ground fault is recovered by the maintenance person without breaking the resistor.

Abstract: A fiber optic to electrical conversion unit includes front and rear modular design with rear card modules conditioning signals to be passed to front modules. A frame synchronization method transmits a stream of multiplexing frames and periodically inserts a synchronization word in the stream. Prediction of the next synchronizing word in the receiving unit reduces the need to search for a synchronization word in the stream. Loop current regulation in a two-wire loop between a central office and a PBX uses a transformer serially connected in the two-wire circuit with a regulation circuit which holds the current in the loop within a predetermined range to permit the transformer to be held to a relatively small size. High frequency noise bypassing is accomplished by forming capacitor loops from the power connection to the ground connection of the component near to the component.

Abstract: Reducing the power consumption of loads fed by one or more power supplies is achieved by the use of apparatus which determines the power supply output and, upon the occurrence of a predetermined condition, generates a signal to the power-consuming loads. In response to this signal, the loads alter their mode of operation so as to reduce the overall demand on the power supply. Several implementations of this load-shedding technique, which is particularly suitable for use in a communications system, are disclosed.

Abstract: A battery-less telephone subset retains data in its processor memory with a storage capacitor which is kept charged by three controlled charge circuits which deliver power from the line to the capacitor under various line conditions and phone states. The first charge circuit charges the circuit initially, the second charge circuit then charges the capacitor (6.8 v) while all subsets remain on-hook (line voltage 50 v). When a second subset goes off-hook and the line voltage drops (to about 10 v), the capacitor is charged by the third charge circuit at a lower voltage (3.5 v) that is nevertheless sufficiently high to maintain the first subset's on-hook functions. Preferably, the third circuit is controlled by the subset's line switch control circuit, thereby minimizing the number of required components.

Abstract: A line driver is provided for driving a twisted pair of lines with complementary data signals. The driver comprises NPN and PNP transistors arranged as complementary emitter followers with their emitters connected to a biasing resistor network to provide an arrangement capable of being used as a "wired-or" output.

Abstract: An interconnecting apparatus for a subscriber premises which allows the DC battery providing sealing current to the tip and ring telephone lines serving the premises to be used as a backup battery for a subscriber terminal and which allows the supply serving the subscriber terminal to be used to charge the central office battery and provide sealing current when the latter battery is low.

Abstract: Disclosed is a terminating circuit in a battery feed circuit of an electronic exchange system. The battery feed circuit comprises two transconductance amplifiers connected by a coupling capacitor, for supplying a direct current through a ring terminal and a tip terminal to a load. Each of the transconductance amplifiers comprises an operational amplifier; a resistor connected between the output end of the operational amplifier and the tip terminal or the ring terminal, and an impedance unit connected between the inverting input terminal of the operational amplifier and the output end. The impedance unit has an impedance determined in such a way that the required terminating impedance of the battery feed circuit when viewed from the tip terminal and the ring terminal is formed only by the internal elements including the impedance means and the resistor, whereby an external larger-size capacitance capacitor for matching becomes unnecessary.

Abstract: A power supply (ringer power supply) for a telephone exchange comprising a first switching circuit for receiving and subjecting direct current to high frequency switching by means of a switching element, a converter transformer connected to the switching circuit, a smoothing circuit connected to the secondary side of the converter transformer, a second switching circuit connected to the output stage of the smoothing circuit and used for switching the input current by means of a transistor bridge of a plurality of transistors for being alternately turned on, a direct-current bypassing diode connected between the input and output terminals of each transistor, a driving circuit for driving each of the transistors in accordance with a predetermined driving signal, and a driving signal generator circuit for generating the driving signal for setting timing to prevent the period during which a transistor is turned on from overlapping the one during which another transistor is subsequently turned on, permitting a red

Abstract: A private branch exchange for use with different types of telephone sets comprises a current detection device such as a photo-coupler for detecting a current flowing through a data line connecting to a multifunction telephone set to discriminate among different types of telephone sets and a current limiting circuit for limiting a current supplied from a power source device through a voice line in accordance with an detected output from said current detection device.

Abstract: A battery feed circuit including a main battery feed part and its peripheral circuits provided in a line circuit of a switching system.

Abstract: In a device for providing stand-by power to an electrical apparatus, such as a telephone switching system, the battery contained therein is maintained at a positive plate polarization of about 20 to 40 millivolts per cell.

Abstract: The amplifier circuit is arranged such that an open drain type amplifying circuit is provided on the side of output of a differential amplifying circuit having an active load. In this arrangement, the differential amplifying circuit is brought into a non-operational state, and at the same moment an electric potential of output of the differential amplifying circuit is fixedly set to a predetermined level. Consequently, the open drain type amplifying circuit is surely kept in the non-operational state.

Abstract: The invention provides a combination in a SLIC for telecommunication applications of ac impedance synthesis, e.g. raising the impedance of battery feed resistances by feedback techniques; in combination with real battery feed resistors and a dc block transformer. A dc blocked transformer is coupled to line current feed resistors and a feedback loop network to synthesize the desired input impedance, such that the feedback network incorporates both positive and negative feedback. A loop stabilizing resistor is used in shunt with the dc blocked transformer secondary to reduce gain peaking and phase shift.

Abstract: A telephone circuit, which may be monolithically integrated, for feeding a subscriber's telephone line which is coupled via the circuit to a supply voltage generator. The circuit supplies the line with an impedance having a first predetermined value up to a given value of the line current, beyond which is supplies the line with an impedance of a second value greater than the first. The circuit is electrically equivalent to a voltage generator, identical to the supply voltage generator, having circuit components solely of the resistive type connected in series therewith.

Abstract: A trunk circuit is disclosed for coupling a bidirectional lead pair, such as balanced tip and ring leads, to a pair of unidirectional leads such as unbalanced input and output leads. The trunk circuit incorporates a small inexpensive transformer for effecting this coupling and for providing large common mode signal isolation and correct longitudinal balance. Circuitry is provided for matching the nominal balanced AC and DC line impedances. The trunk circuit also provides circuitry for generating dial pulse signals under control of a microprocessor or other external controller.

Abstract: A current supply circuit for supplying a speech current via subscriber's lines to a telephone set, in which a pair of constant-current circuits, each so constituted as to hold the potential between the base and the emitter of a control transistor therein to be consant, is connected across the subscriber's lines so that the control transistors are connected in series to a DC power source. A constant-voltage circuit is connected across the bases of the control transistors for making the voltage of the base-emitter paths of each of the control transistors to be constant. At least one of the constant-current circuits may be connected across the subscriber's lines via a light emitting diode of a photo coupler.

Abstract: An arrangement for supplying electrical power from a telecommunication central office to a remote network termination employs the wires of a two-wire digital subscriber loop in parallel using earth ground as a return path. At the central office, two power supplies separately provide power to the two wires of the loop in parallel and the current supplied by the two power supplies is added at the remote interface by means of a center-tapped transformer coil which is part of the transformer used for the transmission of digitally encoded voice and data signals. A DC-to-DC converter connected to the center tap provides the required power to the interface circuitry. The DC-to-DC converter is grounded to earth ground through a low-pass filter which is designed to block higher frequency noise signals.

Abstract: The present invention relates to the D.C. supply for a subscriber control system, and consists essentially in supplying the control system from the exchange solely in response to a request, such request being emitted either by the exchange or by the control system, a preamble message being emitted in-line by the control system in order to initialize a communication in the latter case. The invention is applicable to the digitalization of the subscriber's telephone.

Abstract: An apparatus for supplying current to a subscriber telephone set (R.sub.L) connected to a telephone exchange via a two-wire line departing from a a-wire and a b-wire output terminal in the arrangement. The arrangement includes two analogue amplifiers (2, 3) each with its output connected to said respective a-wire and b-wire output terminal, through which the combined DC-current and current representing the speech signal are fed out to the line. The apparatus further includes a voltage source with the pole voltage (E.sub.B) and its poles connected to two voltage supply inputs on each amplifier (2, 3), the output of the first amplifier (2, 3) being kept at a fixed potential. Three signal sources (5, 6, 8) are connected to the inputs of the amplifiers, the respective signal contribution of these sources being added for controlling the output magnitudes of the amplifiers. A first signal source (6) constitutes the reference signal source and has a fixed signal contribution.

Abstract: An apparatus for applying current to a subscriber line telephone set (RL) with associated two-wire line connected to a telephone exchange. The apparatus includes two analog amplifiers (5,6) each with its output connected to one of the two wires of the line, and feeding out on the line the combined DC current and current representing the speech signal. A DC/DC converter supplies voltage to an at least one of the amplifiers. To form a control voltage to the DC/DC converter, a cascade connection of a differential amplifier (1), a lowpass filter (2) and an adding circuit (3) are arranged between the line connection terminals and the control signal input of the DC/DC converter.

Abstract: A battery feed circuit for a subscriber line includes first and second feed circuit parts, each supplying a constant current to a corresponding subscriber line. The first and second feed circuit parts are provided with at least one of a common mode noise suppressor and a power source noise suppressor. The common mode noise suppressor includes first and second reference voltage output circuits and an intermediate voltage output circuit to produce the voltage between the first and second subscriber lines and superpose the same onto the first and second reference voltages. The power source noise suppressor functions to cancel the power source noise voltage at the output, of the first and second feed circuit parts.