Abstract: Distortion and instability due to echoes in conference communications is reduced through the use of an echo estimating filter disposed in a conference bridging circuit. This circuit includes a signal combiner which receives information signals from each of the parties in the conference communications and provides an output signal which is a combination of the received information signals and an echo compensation signal. The echo estimating filter provides this echo compensation signal in response to the combiner output signal. Advantageously, the echo estimating filter can be fixed or adaptive. In the latter case, the adaptation can be in response to the received information signals or to training sequences.

Abstract: A facsimile machine includes a help feature for providing the user with a hard copy of "help" information, outputted via the facsimile printer, relevant to the existing operating mode of facsimile machine at the time the help feature was activated. If the help feature is activated when the facsimile machine is in a standby mode, the user is prompted to request a menu or to select the type of help information to be outputted in facsimile form. If the help feature is activated when the facsimile machine is in an active operating mode, (e.g., programming, service or error modes), the outputted help information is selected by the facsimile machine based on machine sensor status and/or the present software state. The help feature is activated by a predesignated push button or access code.

Abstract: A method for forming a grating in a photosensitive medium such as a photosensitive optical fiber. The method comprises impinging a pair of interfering, actinic beams onto the medium, and during the impinging step, advancing the illuminated portion of the interference pattern relative to the medium. The advancement is carded out without changing the phase, or registration, of the interference pattern. According to one embodiment of the invention, a grating having a spatially dependent period is produced by varying the wavelength or the intersection angle of the actinic beams during the advancement. According to a second embodiment of the invention, a grating having a spatially dependent refractive index perturbation is produced by varying the dose of actinic radiation received by the medium during the advancement.

Abstract: Intersecting quantum wells form a T-shaped structure. Quantum bound states exist due to the spreading out of the wave function in the T-junction region. The confined state leads to formation of a quantum wire in which one-dimensional carrier behavior extends along a wire-like region defined by the intersecting planes of the two wells. By embedding such a region in a T-shaped optical waveguide, a quantum wire laser characterized by low-threshold stimulated emission in the one-dimensional quantum limit is provided.

Abstract: Disclosed is a network interface unit which comprises a multilayer modular design. The upper layer includes an array of customer bridges. The lower layer includes a splice chamber and a protector panel. The splice chamber includes openings which permit a plurality of units to be stacked. The upper layer is removably mounted to the lower layer so it can be used with existing building entrance protectors which have no interface section.

Abstract: A power converter circuit requiting the periodic reset of a core of the power transformer includes a control circuit operative to alter a response of the converters voltage regulation feedback control to limit and/or control the power switch duty cycle to regulate a voltage of the reset capacitor whenever the reset capacitor sustains a voltage above a preset threshold.

Abstract: Sine waves are generated by a port circuit processor of a telephone switching office by accessing a look-up table stored in a memory associated with the port circuit processor. Entries in the look-up table are accessed by using table steps or .DELTA.'s which correspond to the frequencies of the sine waves to be generated. The table steps or .DELTA.'s are changed for different sine wave frequencies and may be changed each bit period. Whether changed or not, a first fractional portion of the table step or .DELTA. for the previous frequency is combined with a second fractional portion of the table step or .DELTA. for the current frequency with the first and second fractional portions adding up to one. In this way, an X sample per second data stream, X equaling the base sample rate of the look-up table, that precisely matches a Y bits per second rate, Y equaling the transmission rate of the data stream, is generated.

Abstract: This invention embodies single mirror light-emitting diodes (LEDs) with enhanced intensity. The LEDs are Group III-V and/or II-IV compound semiconductor structures with a single metallic mirror. The enhanced intensity is obtained by placing an active region of the LED having from two to ten, preferably from four to eight, quantum wells at an anti-node of the optical node of the device created by a nearby metallic mirror. Such multiquantum well LED structures exhibit enhanced efficiencies approaching that of a perfect isotropic emitter.

Abstract: Encoded blocks of video information are selected for transmission at a plurality of channel rates based on the corresponding location of the portions of the video image represented by the encoded blocks. Each encoded block is designated an image type which determines its transmitted channel rate. The image types are associated with spatial positions of a video image such that encoded blocks within a first area of the video image are designated a first image type and encoded blocks within a second area of the image are designated a second image type. In general, data blocks representing the central portion of the video image are transmitted at a channel rate having less susceptibility to noise or other degradation, thereby ensuring that such portion can be received in fringe areas.

Abstract: A digital system in which an integrated circuit complements the signaling protocol of non-standard devices so that the non-standard devices can operate and communicate with other devices as if the non-standard device were able to support the signaling protocol of the other devices. Embodiments of the invention are taught which reduce the overall power consumption in the system, which enhance the functionality of the system, and which reduce the overall package count in the system.

Abstract: A membrane is supported at its edge by an annular, tapered skirt structure. The skirt strengthens the attachment of the membrane to the support ring and reinforces the edge region where the membrane would otherwise tend to fail. Stress concentrations are reduced by providing a skirt or featheredge, on the interior side of the skirt, that meets the membrane at a relatively small effective contact angle. In a preferred embodiment, the membrane is made by depositing a polysilicon layer on the surface of a substrate of silica-based glass. A portion of the substrate is removed by an isotropic, selective etchant, such that a portion of the polysilicon layer remains as a free-standing, tensile film supported by a remaining portion of the substrate.

Abstract: Absorption properties of an optically active medium can be changed drastically by a Fabry-Perot microcavity. Optically active medium of the cavity includes a host material which is not optically active and at least one rare earth ion which provides optical activity to the medium. The Fabry-Perot cavity is designed to be resonant with excitation wavelength of an absorption band of the host material. The excitation is provided by a source of radiation positioned such that the radiation impinges on the cavity at an angle within a range of from zero to less than 90 degrees from the normal to the top surface of the cavity. In one embodiment Er-implanted SiO.sub.2 is used as the optically active medium. SiO.sub.2 :Er has an absorption band at 980 nm and an emission band at 1.55 .mu.m due to 4f intra-atomic transitions of Er.sup.3+ ions. The Fabry-Perot cavity is designed to be resonant with the 980 nm absorption band of SiO.sub.2 :Er.

Abstract: A spread spectrum receiver for use in spread spectrum communication systems is disclosed. The spread spectrum receiver of the present invention includes an analog-to-digital converter for receiving an analog spread spectrum signal, and for converting the received analog signal to a digital signal. The spread spectrum receiver also includes a digital frequency offset correction device, for modifying the digital signal in accordance with a frequency correction term signal to thereby correct for frequency offset in the received analog signal. The spread spectrum receiver also contains a Rake receiver. The spread spectrum receiver searches through the modified digital signal to identify M of the main and multipath return signals having the strongest signal strengths.

Abstract: This invention relates to arrangements for simplifying the transfer of a source of telecommunications signals, such as a telecommunications customer line or telecommunications trunk, from a first port of a switching system to a second port of that same switching system. Such a transfer requires a transfer of a connection in the outside plant, usually in a manhole, and establishment of a connection from the outside plant to the second port, usually in a distributing frame of the switching system. Translation data is stored for the second port to indicate availability of the second port for assignment to a customer, and, in one embodiment of the invention, to identify the customer to be connected to that second port. In accordance with that embodiment of the invention, the customer line to the first port is tested in the manhole to verify the identity of that customer; the line to the second port is tested to see if the translation data for that second port comprises the same customer identification.

Abstract: A fast turn-off circuit for solid-state relays or the like. The relay has a photodiode array for controlling the conductivity of an output transistor. A JFET switch closes to discharge the gate of the output transistor when a photodiode array stops producing current. A bipolar transistor switch, upon detecting the JFET switch closure, discharges the photodiode array.

Abstract: The effects of polarization dependent hole burning and/or polarization dependent loss are reduced by modulating the state of polarization (SOP) of an arbitrarily polarized optical signal being launched into the transmission path periodically through a predetermined sequence of polarization states. The sequence of polarization states is selected such that on average the launched modulated signal excites substantially all possible polarization states with substantially equal probability, independent of the input SOP to the polarization modulator. In one exemplary embodiment, the SOP is modulated by a combination cascade of a rotating half-wave plate followed by a quarter-wave plate, which rotates at a different angular speed. In another exemplary embodiment, the SOP is modulated by a combination cascade of two variable phase retarders oriented at fixed angles of 0.degree. and 45.degree., where the modulation frequencies of the two retarders are substantially different from each other.

Abstract: In a master/slave multiprocessor system, process execution tasks are allocated on the basis of anticipated execution time. Work which can be performed by either the master or the slave is entered on a double ended queue in a non-descending order of anticipated execution times. Processes having high anticipated execution times are selected for execution by the slave processor and processes having low anticipated execution times are selected for execution by the master processor. Anticipated holding times are computed on the basis of the time spent by the slave computer in the execution of a segment of a process without requiring interaction with the master processor. The slave processor records the time spent in execution each time a segment of the process is completed and the process has to be returned to the master. The master uses the recorded time as a measure of the anticipated execution time for a next segment of the same process.

Abstract: A dielectrically isolated photodiode having an increased p-n junction size with improved photo-carrier collection efficiency. The photodiode comprises a first layer of semiconductor material formed on the bottom and the walls of an isolation region; a second layer of semiconductor material formed on the first layer. The second layer forming a first p-n junction with the first layer and having opposite conductivity type compared to that of the first layer. The photodiode also comprises a third layer of semiconductor material formed on the second layer and electrically coupled to the first layer. The third layer having the same conductivity type as the first layer and forming a second p-n junction with the second layer. During operation, the first p-n junction functions to collect photo-generated carriers that extend to the bottom and walls of the isolation region, thereby increasing the active collecting p-n junction area per isolation region area to improve efficiency of the photodiode.

Abstract: A packaged device with a lead frame, a lead frame and an article of manufacture comprising a base metal, a layer of nickel on the base metal, and a protective composite of metal layers on the nickel. The composite includes, in succession from the nickel layer, a layer of palladium or soft gold strike, a layer of palladium-nickel alloy, a layer of palladium and a layer of gold. The palladium or soft gold strike layer acts primarily as a bonding (an adhesive) layer between the Ni and Pd-Ni alloy layers and as a layer that enhances reduction in porosity of subsequent layers, Pd-Ni alloy layer acts as a trap for base metal ions, Pd layer acts as a trap for Ni ions from the Pd-Ni alloy layer, and the outer gold layer synergistically enhances the quality to the Pd layer. The various layers are in thickness sufficient to effectively accomplish each of their designated roles, depending on the processing and use conditions.

Abstract: An infrared collector which employs a non-directive concentrator to concentrate the infrared radiation received in the collector on a detector. In a preferred embodiment, the concentrator is a plastic hemisphere which has an array of PIN diodes glued to its flat side. The hemisphere may have any radius which is greater than or equal to a value dN, where N is the index of refraction of the plastic making up the hemisphere is N and d is the distance from the center of the array of diodes to the most remote part of the infrared-sensitive material. The fact that the concentrator is non-directive obviates the need to aim receivers employing the concentrator at transmitters. The receivers and transmitters need only be in line of sight of each other. The concentrator may further be used generally to concentrate infrared and visible radiation.