Abstract: Highly accurate, self-calibrating data processors and methods for calibrating the same use internal analog references with negligible time and temperature drifts. A first input reference signal set generated by any accurate, precision analog reference is applied to a data processor. The corresponding output response is compared to the theoretical ideal output response to determine the data processor's initial gain and offset errors. This information can be stored in non-volatile memory, recalled, and used to compensate for the data processor's initial gain and offset errors during actual use of the data processor. Subsequent errors due to time and temperature drifting can be determined by comparing the output responses to a second input reference signal set which is generated by the internal analog reference. The subsequent errors can be combined with the initial errors to compensate for system errors within the data processor.

Abstract: Resonant DC to DC power converter topologies include a PWM-controlled flyback converter having a single transformer and a primary side resonant subcircuit that is optimally controlled to minimize reverse recovery losses. A second transformer may be added wherein the primary windings are connected in series, the first transformer having substantially greater inductance than the second transformer to more efficiently transfer energy over a wide range of output load conditions. A combined forward-flyback resonant converter utilizing a load-side buck loop for increased power delivery performance and start-up circuitry for initial power connection of the converter to a voltage source utilizing a hysteresis protection circuit are also disclosed.

Abstract: A voltage detection circuit, in conjunction with a power supply system for ringing voltage generation in a remote telecommunications unit, monitors the operating voltage level of the remote unit and, when an undervoltage condition is detected, causes a ringing reference-signal generator to collapse the reference (AC) sine wave into a fixed (DC) state and holds it in this state for a preselected time, thereby substantially reducing the ringing-signal current load and allowing the operating voltage level to restore. The features of the invention allow for continued processing of calls in progress and for incoming call completion during an undervoltage condition. The increased reliability and integrity of the power supply system allows for extended power supply feeder distance to the remote telecommunications unit.

Abstract: Alternative methods and apparatus for introducing narrowcast transmission signals into a fiber optic broadcast network utilizing rare-earth-doped fiber amplifier technology are disclosed. The methods and apparatus include utilizing an existing 1480 nm pumping laser in an erbium-doped fiber amplifier to transmit a narrowcast signal into a 1550 nm broadcast transport fiber. The 1480 nm narrowcast signal is split off from the amplified 1550 nm broadcast signal(s) in order to bypass a 1550 nm optical isolator located at the output of the amplifier and then recombined with the broadcast signal(s) after the isolator.

Abstract: A protocol for fiber-optic communication systems, or other communication systems based on transmission of unipolar pulses having wide dynamic range provides for information to be transmitted in packets having a predictable time slot for each transmitter. The receiver for such protocol has a first relatively long RC time constant mode conditioned for reception of data packets whose time of arrival is well predictable and a second relatively short RC time constant mode conditioned for reception of asynchronous randomly received packets. In the relatively long RC time constant mode, each packet includes a preamble having a first clamp interval in which no pulse is transmitted, and a second clamp interval in which a continual pulse is transmitted. A transducer on the receiver translates the packets of pulses into differential electronic signals on first and second outputs.

Abstract: An office interface unit (OIU) transfers data and signaling between a telephone local exchange and distribution lines. Information from the telephone local exchange is contained in repetitive frames containing signaling time slots which each contain two distinct nibbles of information. The OIU translates each local exchange signaling channel into first and second internal signaling channels, each internal signaling channel containing information representative of one signaling nibble therein. This simplifies DSO time slot interchange in the OIU. In addition, each internal signaling channel is provided with at least one additional significant signaling bit thereby providing additional signaling states so that the OIU equipment can account for multiple types of telephone local exchange equipment easily.

Abstract: An assembly capable of enclosing and sealing an intermediate section of an optical fiber includes a plurality of sealing mechanisms arranged such that the assembly can be entered to gain access to electronic components for servicing without affecting an environment occupied by optical fiber broken out of an optical fiber cable. Accordingly, physical integrity of the exposed fiber, and its associated connectors and splices, is not compromised. The assembly further includes a plurality of card cages, each of which has its own integral backplane having socket connectors which allow for connection to an adjacent card cage backplane within the assembly. During initial deployment of the assembly where less than all card cages for maximum capacity are initially required to be deployed, segmenting the backplane reduces the first installed cost of the assembly.

Abstract: A DC to DC switch mode power supply for a service subscriber interface unit of a fiber optic network includes a source of DC primary power, a main DC to DC switched mode power supply connected to the source of DC primary power and including switching circuitry and rectifier circuitry for supplying DC operating power to the service subscriber interface unit including central office battery power to at least one subscriber loop connected thereto, and a ringing voltage DC to AC switched mode generator connected to the source of DC primary power and including switching circuitry and synchronous rectification circuitry for generating ringing ringing voltage approximating a sine wave supplied as a reference to the synchronous rectification circuitry. A Johnson counter and resistor capacitor network is preferably employed to convert a reference ringing square wave into a sine wave.

Abstract: A predistortion circuit reduces composite second order intermodulation distortion products inherently generated by a laser diode. A radio frequency signal is split into a primary and secondary signal, and the secondary signal is amplified by an amplifier biased at a starvation current level so as to produce intermodulation distortion products having an amplitude relatively large compared to an amplitude of a fundamental generated by the amplifier. The amplitude and phase of composite second order intermodulation distortion products generated by the amplifier are adjusted so as to substantially match those inherently generated by the laser diode by the primary electrical signal, with the products being about 180.degree. out of phase relative to those generated by the laser in response to the primary signal.

Abstract: A method and apparatus implementing the method are provided for controlling optical power output level of a laser diode modulated during a burst mode interval by digital data transitions within a shared logical bus optical communications network and over a predetermined thermal gradient. The method comprises the steps of: optically monitoring a component of the optical output power of the laser diode during each burst mode interval and converting the component into a control signal, establishing a reference signal and comparing the control signal with the established reference signal and for providing a logical condition from said comparison, generating a strobe signal from information related in time to the burst mode interval, storing the logical condition upon receipt of the strobe signal, integrating the stored logical condition over a time period to provide an integrated control signal, and regulating current flow through the laser diode in accordance with the integrated control signal.

Abstract: A telecommunications closure (1) includes a pressure clamp (21) for sealingly clamping mating parts (47, 48) of the closure together so as to form a water tight seal. The clamp member requires no tools during installation and creates no uncertainty as to the generation of appropriate clamp pressure on a sealing O-ring when installed. The pressure clamp includes an over-center latch which is rotatable between a first unlatched position and a second latched position, a clamping pressure generated by the latch increasing to a maximum value as the rotatable latch is moved from its first position to an intermediate position between the first and second positions and then decreases from this maximum value as the latch is moved from the intermediate position to the second position so as to generate a predetermined appropriate clamping pressure when in its second position so as to appropriately compress the O-ring disposed within a groove between the closure parts at their mating area.

Abstract: A method and apparatus for cross-connecting arbitrary fragments of an incoming virtual tributary synchronous payload envelope, or arbitrary fragments of any incoming transmission stream, at a cross-connect element within a communications network is provided without incurring a delay associated with aligning a frame phase of the first digital stream to any arbitrary frame timing reference. The arbitrary fragments are sized smaller than a complete virtual tributary, or equivalent thereof, of the first digital stream, and comprise one or more incoming payload bytes. The incoming payload bytes have incoming identifiers related to their incoming locations and outgoing identifiers related to their outgoing locations.

Abstract: A card cage for housing a plurality of circuit boards and passive optical fiber couplers contains a tray for storing express optical fibers or express optical fiber tubes not to be coupled within the card cage but rather expressly routed through a distribution point accommodating the card cage. The tray has a flexible hinge thereon and means for keeping the tray passively deflected away from the optical couplers for facilitating insertion and removal of optical fibers into and from the couplers. A card cage housing snap fits to a card cage base without requiring screws or other physically detachable elements. The housing also includes a plurality of flexible deflectable clips integrally molded as part of the card cage housing which normally keep the circuit cards or boards within the card cage housing but which are deflectable so as to allow the boards to be slideably inserted and removed from channels within the housing for guiding the boards.

Abstract: A protocol for fiber-optic communication systems, or other communication systems based on transmission of unipolar pulses having wide dynamic range provides for information to be transmitted in packets having a predictable time slot for each transmitter. The receiver for such protocol has a first relatively long RC time constant mode conditioned for reception of data packets whose time of arrival is well predictable and a second relatively short RC time constant mode conditioned for reception of asynchronous randomly received packets. In the relatively long RC time constant mode, each packet includes a preamble having a first clamp interval in which no pulse is transmitted, and a second clamp interval in which a continual pulse is transmitted. A transducer on the receiver translates the packets of pulses into differential electronic signals on first and second outputs.

Abstract: An optical fiber splice tube holder includes a plurality of torsion bars and cantilever bars which provide a resilient retaining force for an optical fiber splice container to be retained therein. The use of torsion bars helps distribute stress generated by a spring force of the fiber splice member holder about a large amount of material so as to achieve an efficient spring construction so that a plurality of splice holders can be accommodated in a reduced space on a fiber storage tray.

Abstract: A transimpedance front end is provided for an optical receiver which includes a photodetector coupled optically to an optical fiber for receiving optical signals over the fiber and connected electrically to the front end. The front end comprises a buffer amplifier connected to the photodetector, a first amplifier selectively connected to the buffer through a first switch and through a first, high value feedback resistor in order to define a first mode low optical signal level amplifier configuration, a second amplifier selectively connected to the buffer through a second switch and through a second, switched low value resistor to define a second mode high optical signal level amplifier configuration, and an optical level sensing and switching control circuit connected to the photodetector for sensing incoming optical signal level and for switching between the first and second amplifier configurations as a function thereof.

Abstract: A printed circuit board apparatus includes a handle which has an extension plate which extends into an optical switch so as to prevent communication between an optical emitter and optical receiver. To remove the printed circuit board apparatus from its associated rack housing, rotation of the handle is first required which moves the plate and which causes the detector to go HIGH and signal to a telecommunications system that the board is soon to be removed so that a graceful switch can be made from that board to a redundant copy thereof. The printed circuit board apparatus further includes a deflectable lever which contacts to ground the rack housing upon inserting the printed circuit board apparatus into its associated rack housing so as to provide electrostatic discharge protection.

Abstract: A coupler for a fiber optic light waveguide has phase space matching optics to increase coupling efficiency. The acceptance phase space of the fiber optic waveguide has two components for light in two orthogonal planes. One of the phase space plots has a straight spine and the other has a bent spine. The phase space matching optics include a graded index lens optically coupled to the phase of a light emitting diode, in the case of a write coupler, which alters the emitted light phase space at a reference plane of the emitted light to match, at the reference plane, the acceptance phase space component having the straight spine. Another lens takes the output light from the graded index lens and alters the phase space further to match the phase space component having the bent spine.

Abstract: A transmit control store is provided for assembling recurrent data packets of information for transmission over an optical fiber communications network from a host digital terminal to a variable number of optical network units, wherein each optical network unit serves a variable number of individual subscriber stations, and wherein each frame contains a programmed number of optical network unit packets wherein each packet has a byte length related to the number of subscriber stations served and bandwidth required thereby.

Abstract: An optical receiver includes a photodetecting device and a wide band video amplifier. The photodetecting device and the video amplifier are coupled by reactive elements which are selected to provide a highly linear and highly sensitive response over a frequency range of approximately 400-950 MHz. The crosstalk between two signals are ten parts per billion when the laser power is at 1 milliwatt and modulation is 25 percent per signal. The noise generated by the receiver is only equivalent to 6 billionth of an ampere. The receiver uses commerically available components.