Abstract: A method and system for handling transport overhead on a ring network. The system includes a ring network having a plurality of network elements communicating a signal along the network. In one embodiment, a method is provided for restoring transport overhead along the ring network. This method includes designating a first of the plurality of network elements as a master network element and inserting a first transport overhead break on the ring network by the master network element. The method further includes detecting a failure of the signal by a second network element and inserting a second transport overhead break on the ring network by the second network element in response to the detection of a failure. Finally, the method includes removing the second transport overhead break under the direction of said master network element.

Abstract: A system of managing memory used by communications tasks of a communications network operating with a multilayered communications protocol. Specially formatted buffers are used to contain data to be passed down the protocol stack of a source node, across a communications link, and up the protocol stack of a destination node. Before entering the source stack, message data is presegmented so that each buffer contains only so much message data as may be transmitted as a single data unit from source to destination, even after all layers of the source stack have added layer headers to that portion. Then, when the buffers are being passed within the source stack, any layer may segment the message data by simply unlinking buffers and adding its layer header to each segment. Inter-layer data passing is by means of exclusive access to buffers by one layer at a time. At the source stack, any layer that must send multiple copies of the message data may checkpoint the buffers and thereby regain the same buffers.

Abstract: A springy, low dielectric retainer device in the form of a rod, a triangle, an ellipse or whatever, is used in a compressed condition to hold RF energy absorber blocks in position juxtaposed "energy leaky" RF circuitry. The absorber blocks are held in position due to frictional forces provided by the compressed retainer. In this manner, the absorber blocks can be re-positioned to obtain optimum amplitude/frequency response characteristics from the affected RF circuit.

Abstract: A circuit is shown for arbitrating between inputs to provide all request inputs with the opportunity to be polled in substantially less time than is the case with known prior art round robin arbiters. This is accomplished by phase delaying the input clock to produce a plurality of different phase clock signals such that multiple arbiter circuits can be polled within a single clock cycle if the first few arbiter circuits do not have a request waiting. With proper speed of operation of arbiter circuits, the phase delay can be of a short enough duration that all of the arbiter circuits can be polled in a single clock cycle. With slower speed arbiter circuits, the total polling time can exceed one clock cycle but still be less than the number of clock cycles of prior art round robin circuits which typically was the number of arbiter circuits times a single clock cycle time duration.

Abstract: N-parallel bits of data are input to a parallel in-parallel out shift register made of n+m n:1 parallel multiplexers and n-parallel bits of either pure data or combined stuff and data bits are output where, for cycles in which stuff bits are inserted, the non-outputted outputted data bits are recirculated for output on a subsequent cycle followed by newly incoming data bits; such is shown used to advantage in a bit stuffing technique where a synchronous payload envelope pattern may be started at a selected location in a synchronous transport signal frame by monitoring a frame starting signal and providing a pattern starting signal at a selected point after the occurrence of the frame starting signal.

Abstract: Constant light output is provided by a laser diode over various temperatures or operating points by adjusting the bias current in accordance with a midpoint of a detected peak and a detected valley of an output power level and adjusting the modulation current amplitude in accordance with the difference between the detected peak and the detected valley output power.

Abstract: An asynchronous parallel data formatter for use in mapping low speed serial asynchronous data signals into a higher speed signal includes a set of latches that receive the data from an elastic store. A time domain multiplexer receives signals from the latches as well as signals from an adder is responsive to one or more signals indicative of a need to recirculate data that provides stuff control signals and a carry signal. A formatter receives signals output from the time domain multiplexer and provides stuff and control bits as needed to complete the payload signal. The present asynchronous parallel data formatter provides sequential data transfer of full data bytes into partial bytes using one clock and a single set of control circuitry.

Abstract: A line unit, used in a line shelf having a line shelf processor and common logic, is provided with an EEPROM device for storing information relative to the line unit. The stored information includes line unit type identification codes, auto provisioning data, gain and equalization adjustment data and signaling translation tables. The data contained within the EEPROM may be utilized by the line shelf processor to provide automatic initialization and provisioning of the line unit when first inserted into the line shelf, and automatic signaling translation so that line unit signaling becomes compatible with a transmission facility connected to the line shelf. The need for factory preset resistors installed in the line unit may be eliminated by storing within the EEPROM a required gain setting.

Abstract: An optical network unit for field installation adjacent to an optical fiber transmission line, for separating multiplexed video and telephony signals for delivery to subscribers residences as electrical signals over metallic drop cables, has a hollow housing formed of heat-conductive material. The unit has a sealing front cover and rear cover, a cable entrance port for cable connections, and a backplane assembly mounted in the housing which incorporates optical-to-electrical signal conversion components and connectors for electrical signals. Slots are formed in the interior surfaces of the housing for positioning a plurality of printed circuit board cards for sliding installation into electrical contact with the backplane assembly.

Abstract: A power coupler that is held in place at two different points along its length to substantially eliminate any movement thereof due to vibration of the environment. One of these holding means comprises a piece of dielectric which snugly encloses the coupler to prevent side-to-side movement while still allowing a vertical adjustment of the coupler element through the holding means. A constant impedance equal to that of an electrically connected circuit is maintained along a portion of the coupler by varying passageway opening sizes. The electrical connection to the circuit, which has a threaded terminal comprising a part of the adjustment means and the other holding means eliminates connector insertion loss and signal reflections inherent in prior art signal interfaces between the coupler and an electrical signal receiving circuit.

Abstract: A routing method, performed by intelligent network elements of a data communications network having SONET applications, for selecting a path from a source network element to a next network element. Each network element has access to a database containing the addresses of its neighboring network elements and their types. To select a next network element, a routing network element first attempts to find a neighboring network element that is the same as the destination network element. If it has no such neighbor, the routing network element then attempts to find a neighbor that is in the same area as the destination, or failing such a neighbor, in the same routing domain. Optionally, the routing network element looks for a neighbor that has been selectively provisioned as a next network element. At each step, candidate network elements are eliminated by using data about their type and application to determine if they call for duplicate paths.

Abstract: A polarity switch changes the direction of DC to various loads in response to a sensed loss of AC and nonessential loads are shed in response to a sensed change in DC polarity at the various loads.

Abstract: An optical splice shelf (10) has optical splice trays (24, 26, 28, 30) stacked inside a frame assembly (14) slidingly withdrawable from a rear panel (12) and attached thereto with cable tray hinge (80) for maintaining no less than a minimum bend radius of optical fibers routed between the rear of the frame assembly and the rear panel; upon withdrawal, the frame assembly can be pivoted downward to expose the rear panel and the back of the frame assembly.

Abstract: In a data port for a digital data system in which latching loopback is implemented, a unique and efficient algorithm is utilized to achieve M out of N control byte recognition. In the algorithm, N-M+1 variable length windows are used to count identified control bytes. The algorithm opens a window when the desired byte has been detected, counts the identified bytes while the window is open, and closes the window when a non-target byte is detected. The counts in the various windows are summed to determine if M bytes have been detected. A window having the oldest byte count is effectively dropped so that the window is available to count newly-arriving target bytes.

Abstract: A method for activating tandem digital subscriber lines separated by a carrier system in a communication link connecting a switch and a network termination is implemented by a microcontroller which interfaces with a digital subscriber line transceiver to extract and transmit activation request information and a programmable gate array to relay and interpret activation information conveyed across the carrier system. The microcontroller intelligently combines the activation information received from the carrier system, the activation indicator bit received from the digital subscriber line transceiver, and the transceiver status to independently activate the digital subscriber lines in a controlled sequence, so that a proper response is conveyed to the T-interface to preclude premature regarding of the physical transmission channel as being transparent.

Abstract: A concept previously used for providing anti-rotational locking of complementary threaded devices is utilized in a RF tuning cavity to minimize anti-microphonic disturbances of the prior art caused by inconsistent ohmic contact between the prior art adjustable length threaded portions. The use of a resilient locking strip embedded longitudinally into the threads of an adjustable resonator provides substantially constant electrical or ohmic contact between the two threaded portions so as to maintain a standing wave in the tuning element. The longitudinal design of the locking strip is such as to prevent or minimize movement of the extremity of the threaded resonator which movement can also effect the resonant frequency.

Abstract: A four-wire line unit interface circuit used on four-wire line units in a line shelf of a digital loop carrier provides all of the logic necessary to access a subscriber line to a line unit interface bus connected to common equipment within the line shelf. Information received from the common equipment includes signaling data, configuration data and provisioning data which is reconfigured and processed by the line unit interface circuit for controlling the subscriber line. Configuration data from the common equipment is decoded to assign time slots on a line unit interface bus to the various channels serviced by the line shelf and to further provide for a timing offset between the transmit and receive strobes provided to each subscriber line circuit. An asynchronously operating microprocessor is provided on the four-wire line unit, and a microprocessor interface is provided to interface the asynchronously operating microprocessor with the data provided on the line unit interface bus.

Abstract: Apparatus for converting a DS3 digital signal in a DS3 frame format to a STS-1 digital signal in an STS-1 frame format as a function of a STS-1 local clock. DS3 AIS/Idle code generation means generates DS3 AIS/Idle code bytes in response to the local STS-1 clock signal. DS3 byte counter counts the DS3 AIS/Idle code bytes and generating an AIS/Idle bytecount enable control signal if the number of DS3 AIS/Idle code bytes is less than a predetermined number of DS3 bytes to be mapped in a given row of the STS-1 frame. STS-1 row counter counts pulses of the STS-1 local clock signal and generates a gapped STS-1 enable control signal, which is combined with the AIS/Idle bytecount enable control signal fed back to enable and disable the DS3 AIS/Idle code generation means for mapping DS3 AIS/Idle code bytes in the given row of the STS-1 frame.

Abstract: A method is illustrated for identifying which one of a plurality of signal transmitting spans in a communication network of signal spans, such as bundles or sets of DS3 signals, has been interrupted by some type of failure. This identification is based on a local level knowledge, as opposed to prior art network level knowledge, by monitoring each circuit in a given span for either a directly observable signal impairment, or an alarm indication signal (AIS) and sending an IDLE whenever a directly observable signal impairment or an alarm indication signal is detected and declaring that the channel immediately upstream from that node has failed when either the directly observable signal impairment or the alarm indication signal is received for longer than a predetermined period of time. Such a determination as to the whereabouts of a failed span can then be used for other processes such as implementation of a network restoration scheme.

Abstract: A method and system for multiple WDM signal compensation compensates optical chromatic dispersion for a plurality of optical signals having predetermined frequencies and each traveling in an optical path associated with the wavelength division multiplexer that forms a multiplex optical signal from the plurality of optical signals. The invention first undercompensates the multiplex optical signal by a predetermined amount so that each of the optical signals has an associated residual optical chromatic dispersion. Then, either before or after undercompensating of the multiplexed optical signal each of the optical signals is individually compensated to remove therefrom the residual chromatic dispersion. The system and method permit simultaneous and independent control of optical dispersion at any desired wavelength, as well as selection of matching compensation for optical transmitters prior to installation. The result is an increase in the usable wavelength range of optical signals for WDM networks.