Abstract: In a communications system, a transmitted signal is typically impaired by phase jitter attributed to power line harmonics and ringing voltages present in a communications channel. In order to properly recover the transmitted signal, the phase jitter in a received signal needs to be eliminated. To this end, an infinite-impulse-response (IIR) filter arrangement is employed in a receiver to estimate the phase jitter and is followed by a demodulator which substantially removes the jitter based on the estimate. The transfer function of this IIR filter arrangement is a function of the autocorrelation of a phase error, the latter being indicative of the difference between the phase jitter in the received signal and the jitter estimate.

Abstract: This invention relates to an Erbium-doped fiber amplifier having multiple stages of amplification for providing enhanced performance. More specifically, optical means is located intermediate first and second stages of doped optical amplifying fibers adapted to receive a pump signal at a pump wavelength where the optical means is adapted to modify the net gain characteristics of the multi-stage amplifier. Presently, all known Erbium-doped fiber amplifiers utilize relatively simple single stage amplifiers which support required ancillary optically passive components such as isolators, filters, pump multiplexers, power monitors and the like at either end of the amplifier.

Abstract: A distributed switching system where calls are processed in one of two call processing modes: 1) in a first call processing mode, available paths through a time-multiplexed switch (TMS) are selected without reference to whether the paths are presently established through the TMS, and 2) in a second call processing mode, the available path selections are made from only established paths through the TMS. Reliability is improved without an addition of hardware to the system because a transition may be advantageously effected to the second call processing mode in response to any system failure where it becomes impossible to select new TMS paths or to control their establishment, but where the established TMS paths at the time of the failure are still usable for new calls. Once such transition is completed, the system can continue to operate to complete calls between switching modules (SMs) in a reduced performance mode dependent on the number of TMS paths established between the SMs at the time of the failure.

Abstract: In a system where a signal constellation is used for data communications, signal points in the signal constellation are selected to represent incoming data. The signal points, thus selected, are transmitted through a channel. The signal constellation is divided into a plurality of regions each including an equal number of signal points. A coding scheme is employed to ensure that signal points within any one region are selected equiprobably, and the probability of selecting any signal point in one region is different from that in another region.

Abstract: Making use of the conceptual and computational similarities between the Karmarkar method and the Kalman filter a controller system is capable of handling the observer function, the minimum time controller function and the minimum energy controller function. The system includes an element that has the computational structure of a Kalman filter. The inputs of this element are qualitatively controlled to deliver the desired results to the remaining computation elements. In a controller for an LP control task, the element develops the dual vector signal used in the affine scaling algorithm by applying information to it as if its task were to estimate the states of a system whose observable output is D.sub.x(k) c, the input is O, the observation noise covariance matrix R is close to zero, the transition matrix is I and the matrix that describes the relationship between the measurable parameters and the observable output is A.sup.T D.sub.x(k).

Abstract: Siloxane compounds formed by the reaction of a hydridosiloxane with vinylsiloxane are employed in a wide variety of uses, e.g., coatings for optical fibers and flexible layers for touch screen cathode ray tubes. These siloxane materials are substantially improved through treatment with a lower alkene such as ethylene to prevent hydrogen evolution and undesirable crosslinking.

Abstract: An arrangement for teleconferencing voice and data is provided through an arrangement that includes a voice bridge that offers individual control of the conferencing setup. The voice bridge comprises a crossbar with crosspoints that include a series connection of two switches and a resistor. One switch of each crosspoint is associated with the row of the crosspoint while the other switch of the crosspoint is associated with the column of the crosspoint. A user, connected to a selected row and column of the crossbar for the "talk" and "listen" functions, respectively, controls the row switches in the crosspoints connected to the user's row and the column switches in the crosspoints connected to the user's column.

Abstract: An undercarpet cable (40) includes a plurality of longitudinally extending interlocking segments (42--42). The segments are designed each to have an optical fiber (33) housed therein or when interlocked in an assembly to provide a longitudinally extending cavity for receiving an optical fiber. The assembly of segments is capable of being routed along at least two paths which are normal to each other. Advantageously, longitudinal relative motion between adjacent ones of the segments and between the optical fiber and the segments is allowed. As a result, the cable may be routed in tortuous paths under a carpet to service workstations as desired.

Abstract: This coding band, in particular for electric cables, is provided, proximate o its longitudinal edges, with perforations adapted to be engaged by the traction elements of a computer printer and with a plurality of prepunched strips which extend substantially transversely to the longitudinal extension of the band. The strips delimit regions for printing identification codes for the cables to be tagged, can be individually removed from the band and can be inserted in a seat defined in a supporting element which is associable with at least one cable to be tagged. The strip further defines teeth for its retention in the seat.

Abstract: A phase diffraction grating apparatus which is usable to generate an array of N spots, where n is an even integer, and the N spots are substantially equally spaced. The generation of an even number of spots is achieved using a translation symmetry in the grating design. Illustratively, the intensities of the N spots are substantially equal. Binary, multi-level, and continuous phase grating embodiments are disclosed. In the case of the multi-level and continuous embodiments, the uniform intensity is obtained using a reflection symmetry in the grating design.

Abstract: Information processing, for example by means of a computer, is served by a tablet in combination with an inputting implement such as stylus or human finger. Such a tablet-implement combination may serve in lieu of or ancillary to other inputting means such as a keyboard. Implement positional information, e.g., as contacting the tablet, depends upon interpolation as between segmenting lines in the tablet. Cost advantage commensurate with resolution/noise desiderata is ascribable to use of analog information (without digitization) in interpolation.

Abstract: Disclosed is a backplane connector with shorting contacts for providing re-routing of signals when a circuit pack is withdrawn from its shelf. Shorting contacts are mounted on a block which is attached to the inside of an insulating shroud surrounding the contact pins. The shorting contacts make electrical contact between pins when a circuit pack is removed, but are otherwise electrically isolated from the pins.

Abstract: An optical communication arrangement is disclosed which utilizes a combination of leadframe and package molding technology to reduce the complexity of the arrangement. In general, a leadframe is utilized for the placement and connection of the required electronic circuitry. A first molding operation is then performed to encapsulate the electronics. If necessary, a metallic plate may then be attached to the housed electronics to provide EMI shielding. An optical device is then coupled to the leadframe, where a separate subassembly may be used to house the optical device. The encapsulated electronics and optics are then simultaneously covered during a second molding operation to form the final package. In one embodiment, an optical subassembly incorporating a connector receptacle may be utilized, where the second molding operation is performed such that the connector receptacle remains exposed. Alternatively, the molded outer package may be configured to include the connector receptacle.

Abstract: A novel optical subassembly arrangement is proposed. The subassembly comprises a silicon-based submount including a plurality of openings for placement of the various optical components utilized to form the optical subassembly. In particular, a silicon wafer is processed (e.g., etched) using conventional techniques to simultaneously form a large number of individual submounts, each submount processed to include a number of openings. The silicon processing may be sufficiently controlled such that active alignment of the components is minimized. An important feature of the design, when associated with an isolated embodiment, is that the silicon submount is formed to include openings for both the laser and isolator optics such that the openings are disposed along a thermal transport path through the silicon substrate from an attached thermoelectric cooler (TEC). Therefore, the laser and isolator optics are maintained at the same operating temperature.

Abstract: A balanced mode transmission system (20) for use in a local area network includes at least one twisted pair of insulated metallic conductors (27--27) which at its end is connected through a transformer to a transmitting computer and to a receiving computer (48). Each pair of conductors adjacent to the transmitting end and optionally adjacent to the receiving end is provided with a longitudinal choke (56,57). Also, a longitudinally extending metallic wire (60) is included in the system and is connected possibly through a resistor to ground at each end. The combination of the longitudinal choke at least adjacent to the transmitting end and the longitudinally extending metallic wire is superbly effective in suppressing electromagnetic interference notwithstanding the absence of shielding.

Abstract: In a flame hydrolysis method for depositing glass soot used ultimately to make optical fiber, a reactant that forms the glassy soot stream is delivered to the torch (20) in liquid form and an ultrasonic nozzle (34) in the torch atomizes the reactant or breaks the reactant into a fine mist without the use of a gas.

Abstract: A high transconductance field effect transistor is realized by controlling the doping level in a conducting channel buried beneath a heterointerface. In one exemplary embodiment, a channel comprising an undoped, high mobility, narrow band gap quantum well in combination with an intermediate band gap layer is formed beneath a heterointerface. The heterojunction interface is between a wide band gap layer and the quantum well region. A charge sheet having the same conductivity type as the wide bandgap layer is formed near the heterointerface. Advantageously, the transconductance is enhanced by conduction in the undoped filled quantum well region.

Abstract: Defect density in a semiconductor process sequence that uses two local oxidations is reduced by using an approximately 1:1 ratio of nitride to oxide thickness in the second local oxidation step and an annealing step.