Abstract: A current sharing circuit provides redundant power supplies with current sharing through the use of multiple feedback loops and existing circuit diodes to generate shared load current within predefined load voltage regulation requirements. A method of sharing current allows adjustment of the feedback loops to accommodate characteristics of the circuit.

Abstract: A communication system includes primary and secondary interface cards. A switching circuit allows both of the interface cards to selectively communicate over a medium without inducing reflection. Further, an automatic detection system is provided to allow a management circuit to identify which interface card is coupled as the primary or secondary card.

Abstract: A fan module having a frame is provided. A fan is disposed within and attached to the frame so as to align with an aperture passing through the frame. A baffle having first and second inclined surfaces in opposition is disposed within the frame. The first surface is for changing the direction of a first fluid flow from the fan, and the second surface is for changing the direction of a second fluid flow so as to direct the second fluid flow through an exit of the fan module.

Abstract: A management system and method are provided to adjust fans used for cooling equipment. The system includes one or more electric fans. The operational speed of the fan(s) is adjusted as the environmental parameters change. For example, the fan speed is increased as the temperature and elevation increase. In addition, fan failure circuitry provides a safe operation feature that increases fan supply voltage when a performance failure is detected.

Abstract: The present invention relates to a method and apparatus for testing components in ATM networks utilizing loop-back based ATM layer testing. The method and apparatus utilize interfaces and identifier codes to send and loop-back test cells along portions of virtual channels to test the virtual channels.

Abstract: Circuits for testing POTS service on a shared POTS/xDSL carrier include microfilters for selective coupling to the subscriber loop side of an xDSL filter associated with a subscriber line interface circuit. Such configurations facilitate testing of the POTS service using an insertion point that is between the xDSL filter and the subscriber loop in a manner that is transparent to subscribers.

Abstract: An apparatus and method are detailed that allows for improved detection of communication devices and/or doublers in an associated physical communication links, in particular on HDSL communication links. The improved device apparatus and method additionally allows for the communication device to identify when all devices on a communication link have been detected and prevent premature termination of a discovery process. The improved device apparatus and method also allows the avoidance of improper detection of communication devices or doublers due to corrupted discovery response messages.

Abstract: A substrate having a conductive plane and a via passing through the conductive plane is provided. The conductive plane contacts the via to electrically interconnect the via and the conductive plane. A gap in the conductive plane separates a surface of the via from the conductive plane to provide an uninterrupted path for electrical current flowing substantially on the surface of the via.

Abstract: A circuit for controlling inrush current to a load is provided. The circuit includes a variable impedance device having a control input. The variable impedance device is coupled between a power supply interface and a load interface. The circuit also includes a control circuit coupled to the control input of the variable impedance device and also coupled to the load interface. The control circuit is adapted to provide a signal at the control input of the variable impedance device which results in a linear increase in applied voltage to the load when the circuit is coupled to an input power source. A resistor is coupled between the first and second terminals of the power supply interface to provide a current discharge path for the control circuit when the circuit is disconnected from the power supply.

Abstract: Circuits for testing POTS service on a shared POTS/xDSL carrier include microfilters for selective coupling to the subscriber loop side of an xDSL filter associated with a subscriber line interface circuit. Such configurations facilitate testing of the POTS service using an insertion point that is between the xDSL filter and the subscriber loop in a manner that is transparent to subscribers.

Abstract: A single backplane for a housing is provided. A plurality of sockets is disposed on a first side of the backplane, where each of the sockets is adapted to receive a repeater. A connector is disposed on a second side of the backplane and is electrically connected to each of the sockets by conductive traces disposed within the backplane. The connector is adapted to plug into a mating connector for connecting each of the plurality of sockets to input and output transmission lines.

Abstract: Embodiments of the present invention provide an electronic device. The electronic device includes a circuit board. A first circuit is disposed on a first side of the circuit board. The first circuit is connected to a first ground plane of the circuit board. A second circuit is disposed on a second side of the circuit board. The second side is opposite the first side, and the second circuit is connected to a second ground plane of the circuit board. Moreover, the first and second ground planes respectively lie in different planes of the circuit board and are electrically interconnected by a conductive trace disposed within the circuit board.

Abstract: A fault warning system controls light sources and a warning signal to provide an indication of fatal and non-fatal faults in a communication system. The circuitry uses a pull-down circuit in electrical communication with light and signal control circuits. The circuit can be operated to activate a first light emitting diode (LED) if an operational status of a monitored circuit is either fatal or non-fatal fault. The circuit can be operated to deactivate a second LED if an operational status of a monitored circuit is fatal, and the second LED remains active if the operational status of the circuit is a non-fatal fault.

Abstract: An electronic circuit card includes a circuit board and a faceplate attached to the circuit board. A connector is mounted on the faceplate such that the electronic circuit card occupies substantially one slot of a housing when the electronic circuit card is contained in the housing. The connector is also mounted on the faceplate to enable contact between the faceplate and a faceplate of an adjacent electronic circuit card for shielding against electromagnetic interference leakage when the electronic circuit card is contained in the housing. A ribbon cable electrically interconnects the connector and the circuit board. A strap is attached to the faceplate. The strap is adapted to secure a mating connector to the connector.

Abstract: A low cost differential voltage limiter circuit provides a feedback to regulate a voltage output of a voltage source. In one embodiment, the limiter circuit includes a transistor coupled to outputs of first and second voltage sources. If a differential voltage between the two sources exceeds a predetermined threshold, the output voltage of the higher source is reduced. In one embodiment, a PNP transistor is used to regulate the high voltage source.

Abstract: Cascade low-pass filters are useful in attenuating the xDSL band in a POTS splitter. The design of the low-pass filter is a sixth-order filter having two stages. A first stage includes a fourth-order filter, preferably with a stop-band frequency of approximately 48 kHz. A second stage includes a second-order filter in cascade with the fourth-order filter. For this filter, the stop-band frequency is preferably approximately 29 kHz. The inductance value of the second stage is relatively small in comparison to the inductance values of the first stage. In this manner, improvements in xDSL band attenuation are facilitated with little or no eroding of the voice band performance such as insertion loss, pass-band attenuation and return loss.

Abstract: Resistance in parallel with inductors in a series leg of the low-pass filter facilitates changing input and output resistance of the filter with little or no change in the reactance of the inductors. Furthermore, the reactance of the capacitors in the shunt legs of the filter will be substantially unaffected. This assists the designer in matching the impedance of the filter in the pass-band while still providing substantial impedance mismatching in the stop-band without substantially affecting the characteristics of the filter. Facilitating impedance matching in the pass-band and impedance mismatching in the stop-band is accomplished without the need for more complex active components. POTS splitters making use of such filters can facilitate impedance matching of line and load termination in a telecommunications system in response to signals within the frequencies of typical analog telephony service while providing impedance mismatching in response to signals within the frequencies of typical xDSL service.

Abstract: A system and method for protection switching in a transmission network is described. A protection switching mechanism comprises a multiplexer, a transmission path for each output of the multiplexer and a remote circuit. The multiplexer has an input coupled to receive an input signal and a plurality of outputs to output a plurality of output signals. Each transmission path is coupled to receive an associated output signal from the multiplexer. The transmission paths further include one or more redundant transmission paths, wherein signals directed to a faulty transmission path are redirected to an associated redundant transmission path. The remote circuit is used to selectively switch a redundant transmission path for a faulty transmission path at a subscriber.

Abstract: An embodiment of the present invention provides a faceplate for a circuit board. The faceplate has first and second prongs protruding from a first end of the faceplate respectively at first and second sides of the faceplate. The first and second prongs are adapted to engage a housing to aid in inserting the circuit board into the housing. A tab protrudes from the first end of the faceplate at a front of the faceplate. The tab lies substantially between the first and second prongs. The tab is adapted to engage the housing to aid in extracting the circuit board from the housing.

Abstract: A modular telecommunications system architecture creates individual system function modules, and allows a modular architecture supporting a wide array of configurations for the telecommunications system. Each module is operated through an application interface between a driver set and the module, and the application interface is defined so as to accommodate a number of different drivers for each of the modules. This modular architecture allows easy swapping of modules, and modification of modules, without requiring reprogramming of the application interfaces.