Abstract: A regulated power supply interface has a current feedback and voltage level shift circuit that monitors power supply output (load) current and controllably diverts current to a current reference node. A differential amplifier-based, voltage feedback and voltage level shift circuit monitors the load voltage and controllably diverts output current to the current reference node. A current mode setpoint circuit has multiple voltage dropping current paths, through one or more of which a summation of the diverted load currents are programmably directed, to generate a control voltage for controlling the operation of a pulse width modulator unit of the regulated power supply.

Abstract: A ground fault current-limiting circuit for limiting telecommunication wireline voltage and ground fault current to prescribed safety parameters has a ground fault current sense resistor and associated line voltage control circuit installed in a ground-coupling link to the center tap of the output winding of a bipolar voltage converter's output transformer. The control circuit compares ground fault current of either polarity flowing through the sense resistor to a prescribed value. In response to this current limit being exceeded, the control circuit produces an output signal that causes the power source to reduce its output voltage so that the ground fault current will drop to within acceptable limits.

Abstract: A electrical power control mechanism ensures start-up of all telecommunication devices (repeaters and a remote terminal) along a span-powered wireline. Input voltage start-up thresholds of power control circuits at the devices are higher than the steady-state voltage across the repeater closest to the span supply, when the span voltage is at a minimum DC wireline voltage that sustains operation of all devices. The maximum input voltage start-up threshold of a device is less than the maximum voltage that could be applied during start-up, and the remote terminal has an input voltage start-up threshold value higher than that of any repeater. The maximum standby current of each device is specified, and input power is limited to its steady state maximum during start-up.

Abstract: A power management circuit for a remote access platform extracts power from a wireline for powering a ring generator that generates a ringing voltage signal that is distributed to a plurality of subscriber circuits. A power-limited voltage converter steps up the wireline voltage to a higher ‘isolating’ voltage, charging a capacitor coupled to the ring generator. A monitor circuit reduces the power that the power-limited voltage converter can draw, if the wireline voltage drops too low. This prevents the wireline voltage from collapsing should the remote terminal be deployed at a distance from wireline voltage source (the central office) greater than its specified capability.

Abstract: A redundant ringing signal generator subdivides a ringing signal bus into multiple ringing bus segments. A plurality of redundant ringing voltage generators sourcing internally and/or externally ringing voltages are individually and selectively connectable to the multiple ringing bus segments. In the event of a prescribed anomaly in the ringing signal sourced by a ringing generator, the faulty ringing signal is automatically disconnected from its associated ringing bus segment, and that ringing bus segment is connected to a redundant ringing signal source, provided by either the same or another ringing generator.

Abstract: A power supply system has redundant regulated power supplies, whose output ports are diode-ORed to an output node. One of the power supplies outputs a regulated output voltage that is sufficient to meet current demand of a load coupled to the output node. Each power supply has an associated monitoring circuit that monitors the voltage drop across its OR-ing diode. The monitoring circuit for a non-dominant power supply controls its operation so that the non-dominant supply provides a reduced current through its diode to the output node that is less than the current demand of the load, but sufficient to forward bias the diode, and thereby enable the non-dominant supply to immediately respond to a load change, such as an interruption in the operation of the dominant power supply.

Abstract: A ringing voltage power management circuit is configured to extract an isolated high-value intermediate voltage from a central office powered digital subscriber line through a current limiting circuit, and to charge a storage capacitor that serves as an energy reservoir for the ring generator of a subscriber line circuit. The storage capacitor and the current limiting circuit isolate the peak power drawn by the ringing load from the telephone line and translate the ringing signal's (20 Hz) ripple to the sub-Hz oscillations of the ringing cadence.

Abstract: A regulated power supply interface has a current feedback and voltage level shift circuit that monitors power supply output (load) current and controllably diverts current to a current reference node. A differential amplifier-based, voltage feedback and voltage level shift circuit monitors the load voltage and controllably diverts output current to the current reference node. A current mode setpoint circuit has multiple voltage dropping current paths, through one or more of which a summation of the diverted load currents are programmably directed, to generate a control voltage for controlling the operation of a pulse width modulator unit of the regulated power supply.

Abstract: A power management circuit for a remote access platform extracts power from a wireline for powering a ring generator that generates a ringing voltage signal that is distributed to a plurality of subscriber circuits. A power-limited voltage converter steps up the wireline voltage to a higher ‘isolating’ voltage, charging a capacitor coupled to the ring generator. A monitor circuit reduces the power that the power-limited voltage converter can draw, if the wireline voltage drops too low. This prevents the wireline voltage from collapsing should the remote terminal be deployed at a distance from wireline voltage source (the central office) greater than its specified capability.

Abstract: A ground fault current-limiting circuit for limiting telecommunication wireline voltage and ground fault current to prescribed safety parameters has a ground fault current sense resistor and associated line voltage control circuit installed in a ground-coupling link to the center tap of the output winding of a bipolar voltage converter's output transformer. The control circuit compares ground fault current of either polarity flowing through the sense resistor to a prescribed value. In response to this current limit being exceeded, the control circuit produces an output signal that causes the power source to reduce its output voltage so that the ground fault current will drop to within acceptable limits.

Abstract: A processor controlled mechanism automatically determines from a location such as a central office whether termination equipment installed at a remote end of a wireline link is span-powered, or is powered locally. It then applies a voltage to the wireline link that is appropriate for the identified type of termination equipment. This eliminates the need for two separate central office loop-powering devices. In the course of making the determination, nothing higher than a safety extra low voltage is applied to the wireline link, to comply with Underwriter's Laboratory standards for locally powered customer premises equipment.

Abstract: A power supply system has redundant regulated power supplies, whose output ports are diode-ORed to an output node. One of the power supplies outputs a regulated output voltage that is sufficient to meet current demand of a load coupled to the output node. Each power supply has an associated monitoring circuit that monitors the voltage drop across its OR-ing diode. The monitoring circuit for a non-dominant power supply controls its operation so that the non-dominant supply provides a reduced current through its diode to the output node that is less than the current demand of the load, but sufficient to forward bias the diode, and thereby enable the non-dominant supply to immediately respond to a load change, such as an interruption in the operation of the dominant power supply.

Abstract: A power management system is interfaced with both a local utility power source and a remotely powered span, and monitors the power availability for and requirements of DDS terminal equipment. Upon detecting that local utility power is insufficient to operate the terminal equipment, a power limited converter derives power from the phone line. The span power drawn is limited to a fixed value that prevents the line from collapsing. An auxiliary capacitor stores energy from either local utility power or the span, to provide for periods of extended power operation (including ringing the phone).

Abstract: A electrical power control mechanism ensures start-up of all telecommunication devices (repeaters and a remote terminal) along a span-powered wireline. Input voltage start-up thresholds of power control circuits at the devices are higher than the steady-state voltage across the repeater closest to the span supply, when the span voltage is at a minimum DC wireline voltage that sustains operation of all devices. The maximum input voltage start-up threshold of a device is less than the maximum voltage that could be applied during start-up, and the remote terminal has an input voltage start-up threshold value higher than that of any repeater. The maximum standby current of each device is specified, and input power is limited to its steady state maximum during start-up.

Abstract: An active tracking filter reduces low frequency noise (such as a 20 Hz ringing signal) riding on a DC voltage (e.g., on the order of (−40 VDC) applied to a load such as a subscriber line interface circuit (SLIC). A controllable impedance device, such as a FET operating in its linear range, is coupled in circuit between a source of the DC voltage and the load. A low frequency voltage average detector circuit senses the average low frequency variation of the DC voltage. An output voltage sensor senses a DC output voltage at the output of the controllable impedance. A differential error amplifier circuit has a first input coupled to the low frequency voltage average detector circuit, a second input coupled to the output voltage sensor, and an output coupled to a control terminal of the controlled impedance device.

Abstract: An automated battery test system determines the performance capability of an auxiliary battery used as a back-up power source for an electrically powered system in the event of a deficiency in a primary power source. The test system periodically isolates the auxiliary battery from the primary power source and tests at least one electrical characteristic of the auxiliary battery, without preventing the auxiliary battery from being immediately reconnected with the primary power source in the event of a need for a back-up. A multiple alarm arrangement generates audible and visual alarms in response to a detected failure of the auxiliary battery.

Abstract: A programming circuit is coupled to an input/output pin of a device and is operative to generate a selected one of a plurality of electrical stimuli, such as a programming voltage, high and low logic levels, and a high impedance output, to the device in selected electrical state, without affecting normal device operation. The programming circuit includes a switchmode power converter, a linear regulator, and a control circuit. The programming voltage is generated by the switchmode power converter only when required for programming the device. The linear regulator includes a transistor having its collector-emitter path coupled in circuit with the switchmode converter and an output node, as well as to a voltage divider network. The voltage divider network is coupled to the control input of a precision shunt regulator device, which supplies a base reference for the transistor to establish the value of a voltage to be applied provided from the output node to the device.

Abstract: A ground fault detection and line power supply control system protects telecommunication service personnel working on line-powered telephone circuits from ground faults, without requiring that the line power supply be disconnected or shut down prior to a technician working on the line. A ground fault loop sensing current is sourced from an auxiliary DC voltage source that is separate and distinct from the line power supply. This auxiliary DC voltage source is coupled through a ground fault current sense resistor to one side of the powered line, so that detection of a ground fault condition is not dependent upon the supply of current from the potentially hazardous line supply.

Abstract: The need to equip a digital data service termination with the ability to decode digital loopback commands is obviated by a relatively simple hardware modification of a four wire telephone circuit connecting an office channel unit and customer premises equipment. In addition, the signal processing and test control firmware of the office channel unit equipment (OCU DP) is modified so as to realize a simplified circuit configuration for performing loopback testing of the four wire circuit. The hardware modification of the four wire circuit connecting the office channel unit and the customer premises involves the use of a sealing current-dependent relay circuit that responds to respectively different sealing current flow states: normally; interrupted; and reversed, as converted by the OCU DP. The present invention is particularly useful in subscriber loop circuits that are less than 10,000 feet in length, whereby the need for additional amplifier and noise reduction components is obviated.

Abstract: An all rate equalizer provides direct equalization of a data signal which is automatically adjusted based on data rate and transmission line. The equalizer is embodied in a closed loop circuit in which the amplitude of the data signal is the controlled parameter. The DC amplitude of the data signal is restored by an adjustable gain circuit and the bandwidth of the data signal is restored by an adjustable frequency circuit. The signal processing circuits are adjusted by a control processor in accordance with pre-determined tables of control signals corresponding to frequency and gain values required to provide equalization of the data signal for virtually any given data rate and transmission line. The all rate equalizer thereby automatically provides equalization of the data signal that is optimized for any combination of data rate and transmission.