Abstract: A mechanized system distributing the access, test and communication functions to the point of testing, typically the centralized switching facility serving the telephone loops and equipment to be tested. Computer (200) stores information about each subscriber loop in the geographical area served by a system. Front-end computers (220,221) interact with computer (200) to retrieve pertinent data regarding loops to be tested. Each switching facility in an area includes a loop testing system (e.g., 160) that implements the required functions. The communication functions residing in front-end computers (220,221) and loop testing systems (160,161) are coupled via a data communication network (140) in a manner that allows any front-end computer to communicate with any loop testing system. Users of the system control access and test from consoles having the capability of establishing independent communication paths over the national dial network for interactive tests on loops accessed through standard test trunks.

Abstract: A data base management system is disclosed in which data entities are records representing nodes in an entity-relationship directed graph. The body of each node represents one of the physical entities to be utilized while the edges of each node represent relationships between that physical entity and other physical entities. Some of the edges are hyperedges to permit the identification of simultaneous relationships with more than one other node. An application of this system to the assignment of telephone outside plant equipment to telephone subscribers is also described.

Abstract: A toroidal, saturable core reactor (14) is connected in series with the conductors (11,19 and 13,21) of a transmission line. A termination network (16) is connected across the transmission line conductors (19,21). In response to an a.c. test signal transmitted from a generator (48) on one of the conductors (11), a series of voltage spikes are induced at the reactor (14) and superimposed on the a.c. test signal. The superimposed a.c. test signal is returned through the termination network (16) and the other line conductor (13) to a current detector (50) for detecting the spikes. A d.c. signal is then applied along with the a.c. signal. If there is a fault beyond the reactor (14), the spikes will be displaced from their expected positions. If there is a fault before reactor (14), the spikes will not be displaced. For ease in signal discrimination against noise, the d.c. signal is modulated.

Abstract: A multiple-output DC-DC converter has an electronically controllable reactor (64,66) connected in series with each output circuit. In response to variations in voltage of the output circuits (80,82), control signals are fed back to vary the permeance of the electronically controllable reactor (64,66) in each output circuit. The voltage in any output circuit is thereby made independent of input voltage variations and load fluctuations in any other output circuit.

Abstract: A digital concentrator system for use with a plurality of digital carrier systems in the telephone subscriber loop plant is disclosed. The concentrator system comprises a central office terminal (100), a remote terminal (102), and an interconnecting digital carrier path (108). In the transmit direction at each terminal (110,112), a plurality of multiplexed encoded signal streams are demultiplexed and the encoded signals stored. A selected number of encoded signals are retrieved and multiplexed for transmission to a distant terminal (112,110) as a concentrated pulse stream (123,175). In the receive direction at each terminal (110,112), the encoded signals in the multiplexed concentrated stream (125,177) are demultiplexed and stored. The stored encoded signals are retrieved and the original number of encoded signal streams are derived for transmission to the carrier terminal (100,102).

Abstract: Apparatus, and associated methodology, for locating a resistive shunt fault between wires of a cable utilizes the virtual interconnection property of operational amplifier means (112) to cause the coalescing of geographically separated nodes within the cable system. The various embodiments employ the amplifier means in conjunction with an ohmmeter (111) or current source (114)--voltmeter (113) combination and, when necessary, a good conductor (GOOD) which parallels the wires under test, to produce an estimate of the resistance (R.sub.1) of one wire between the fault point and a measurement position.

Abstract: A methodology, and associated circuitry, for locating a resistive shunt fault coupling the cable shield and the conductors of the cable pair under test comprises the steps of: (i) measuring the open-circuited DC resistance (A.sub.1 and A.sub.2) of the pair from test locations (A and B) which straddle the fault; (ii) measuring the short-circuited DC resistance (A.sub.3) of the pair from one of the test points (A or B); and (iii) evaluating the resistance of one conductor of the pair between the fault and the location of the short circuit measurement according to a predetermined quadratic expression involving the three measured quantities. Sensitivity of the measurement technique is reduced by adding a resistor in series with said pair, at either location A or B, so that A.sub.2 is substantially equal to A.sub.1.

Abstract: A digital concentrator system for use with a plurality of digital carrier systems in the telephone subscriber loop plant is disclosed. The concentrator system comprises a central office terminal (100), a remote terminal (102), and an interconnecting digital carrier path (108). In the transmit direction at each terminal (110,112), a plurality of multiplexed encoded signal streams are demultiplexed and the encoded signals stored. A selected number of encoded signals are retrieved and multiplexed for transmission to a distant terminal (112,110) as a concentrated pulse stream (123,175). In the receive direction at each terminal (110,112), the encoded signals in the multiplexed concentrated stream (125,177) are demultiplexed and stored. The stored encoded signals are retrieved and the original number of encoded signal streams derived for transmission to the carrier terminal (100,102).

Abstract: A maintenance termination unit (10) comprises a voltage sensitive switch (30,50) connected permanently in series with each loop conductor (11,13) and an impedance termination unit (18) connected permanently across the loop conductors. Each voltage sensitive switch (30 or 50) comprises a triac (32) connected in series with a loop conductor (11 or 13), a capacitor (34) and resistor (36) connected across the terminals of the triac, and a bilateral switch (60) connected between one of the terminals and the gate electrode of the triac. In response to a signal having a voltage greater than the threshold voltage of the switch, the capacitor is charged to the threshold voltage, thereupon the capacitor discharges insuring that the triac is gated to the ON state.

Abstract: A digital concentrator system for use with a plurality of digital carrier systems in the telephone subscriber loop plant is disclosed. The concentrator system comprises a central office terminal (110), a remote terminal (102), and an interconnecting digital carrier path (108). In the transmit direction at each terminal (110,112), a plurality of multiplexed encoded signal streams are demultiplexed and the encoded signals stored. A selected number of encoded signals are retrieved and multiplexed for transmission to a distant terminal (112,110) as a concentrated pulse stream (123,175). In the receive direction at each terminal (110,112), the encoded signals in the multiplexed concentrated stream (125,177) are demultiplexed and stored. The stored encoded signals are retrieved and the original number of encoded signal streams derived for transmission to the carrier terminal (100,102).

Abstract: When the input power from a resistive source to a DC-DC converter decreases, the pulse width of the switching transistor increases for a given load. When the pulse width increases above a threshold (14), a Schmidt Trigger (36) will operate to generate a plurality of control signals (42,44,46). The threshold is set by a plurality of resistors (28,30,32,34). In response to the control signals (42,46,48), telecommunications traffic through a remote carrier terminal will be adjusted.

Abstract: Digital carrier channels and switching systems in a telecommunications facility may be used to transmit a high-speed data signal between an originating end and a terminating end. At the originating end, the high-speed data signal is distributed either bit-by-bit or sample-by-sample and sequentially to a predetermined plurality of lower speed channels. At the terminating end, the lower speed channels are collated to reconstruct the original high-speed data signal, using submessage sequence identifying signals.

Abstract: A digital concentrator system for use with a plurality of digital carrier systems in the telephone subscriber loop plant is disclosed. The concentrator system comprises a central office terminal (100), a remote terminal (102), and an interconnecting digital carrier path (108). In the transmit direction at each terminal (110,112), a plurality of multiplexed encoded signal streams are demultiplexed and the encoded signals stored. A selected number of encoded signals are retrieved and multiplexed for transmission to a distant terminal (112,110) as a concentrated pulse stream (123,175). In the receive direction at each terminal (110,112), the encoded signals in the multiplexed concentrated stream (125,177) are demultiplexed and stored. The stored encoded signals are retrieved and the original number of encoded signal streams derived for transmission to the carrier terminal (100,102).

Abstract: Substantially identical, unique valued impedance termination networks (26,28) each comprising a resistor (32,38) and a capacitor (34,36) are connected between each telephone subscriber loop conductor (11,13) and ground at the entrance of the loop to the customer's premises (14). The impedance termination networks are balanced to ground for preventing noise from being induced in the loop. In response to an alternating current signal transmitted simultaneously on each conductor from a loop testing apparatus (10), if an impedance termination network is connected between a conductor and ground, the unique impedance value will be measured. The value of the measured impedance is compared with the unique impedance to determine whether there is an open conductor in the loop. Furthermore, a four-layer diode switch (30,40) is connected permanently in series with each loop conductor.

Abstract: The tip and ring leads (15,17) of a tip party transmission facility are reversed before connecting the separate channel units for the tip and ring party channels to bridge lifters (16,18) at the central office, thus permitting selective ringing. Tip party identification for billing is provided by a tip-party indicator (20) inserted in the tip party transmission path at the central office by grounding the tip conductor when needed. The need for rewiring the tip party telephone set is then eliminated by providing separate single party channel units.

Abstract: A control circuit (36) on the primary side of a converter senses the output voltage and is useful for modulating the drive pulse width of a switching transistor (30). An averaging circuit (78) averages the drive pulse and compares this average with an average of the drive pulses for all switching transistors in a system of parallel converters to produce an error signal. In response to the error signal, the drive pulse width is varied so that the load current is distributed evenly among the parallel converters to improve the system efficiency.

Abstract: A digital subscriber loop carrier system (FIG. 1) is disclosed in which voice information and supervisory signal information are encoded in pulse code form and multiplexed together into a single digital pulse stream for transmission between a central office location and a remote subscriber location. In order to provide appropriate timing and decoding of the supervisory signals, a multistate timing circuit (FIG. 4) is provided which permits timing a plurality of periods of substantially different durations by enabling different rate clock pulse sources to be applied to the timing counter.

Abstract: A system (1000) for estimating the frequency of a tone input utilizes sample rate reduction in successive stages and processing by digital cyclotomic filters at each stage. The tone input (2001) is first transformed in network (1100) to yield two quadrature tones. Digitizer (1200) converts the two tones into data words.Buffer (1300) comprises two essentially identical storage arrangements wherein data words are stored and then supplied to succeeding stages. Frequency-shifting unit (1400) effects modulus-one multiplication by processing appropriately selected data words. Word pairs and frequency-shifted versions thereof are processed by cyclotomic filters (1500). Sequential decimation in this system effects a successively refined estimate to the tonal frequency. During each stage of decimation, the filters are configured to provide symmetric coverage of the subband containing the estimate.

Abstract: Coins deposited in a coin telephone are collected or refunded by selectively discharging one of a plurality of capacitors (10,12) through a current limiter (46) for a period just long enough to operate the coin control relay (38) in the telephone. Use of this current limiter minimizes the drain of power from the remote terminal of a subscriber loop carrier system which derives all of its power from a telephone central office. A second current limiter (24) limits the rate at which the capacitors are charged.

Abstract: A digital concentrator system for use with a plurality of digital carrier systems in the telephone subscriber loop plant is disclosed. The concentrator system comprises a central office terminal (100), a remote terminal (102), and an interconnecting digital carrier path (108). In the transmit direction at each terminal (110,112), a plurality of multiplexed encoded signal streams are demultiplexed and the encoded signals stored. A selected number of encoded signals are retrieved and multiplexed for transmission to a distant terminal (112,110) as a concentrated pulse stream (123,175). In the receive direction at each terminal (110,112), the encoded signals in the multiplexed concentrated stream (125,177) are demultiplexed and stored. The stored encoded signals are retrieved and the original number of encoded signal streams derived for transmission to the carrier terminal (100,102).