Abstract: In accordance with the invention an electronic device is provided with a thin film dielectric layer of enhanced reliability. The dielectric comprises a thin film of silicon oxide having maximum concentrations of nitrogen near its major interfaces. In a field effect device, the maximum adjacent the gate enhances resistance to penetration of dopants from the gate. The secondary maximum near the channel enhances resistance to current stress. The maximum near the channel is preferably displaced slightly inward from the channel to minimize effects on carrier mobility.

Abstract: Disclosed is a variable bitrate radio modem unit that includes a transmit section and a receive section that are linked through a host computer. In the transmit section, the host computer is connected to a data modulator equipped with a variable bitrate data generator which in turn is connected to a radio transmit modem. In the receive section, a radio receive modem is connected to a clock/data recovery circuit which in turn is connected to an error detection and correction circuit. The error detection and correction circuit is then connected to the host computer. A connection is established at a predetermined bitrate between two host computers of two individual radio modem units. While data is being transmitted back and forth, the error rate of the data being received is determined by the error detection circuit. If the error rate is larger than a predetermined rate, the bitrate of the radio transmit modem of the transmitting unit is reduced.

Abstract: A processor (100, 500) that executes applications (99) which require access to time slots of a time-division multiplexed (TDM) communications medium (110) uses spare processing capacity and/or spare hardware of the processor to interface to the TDM medium and to implement a time-slot interchange (TSI) function in a simple and low-cost manner. The processor has a control store (104, 300, 504, 604) that stores a bit map of the time slots of the TDM medium. The bit map is either examined by the processor during each time slot (FIG. 2) to determine, or is used by external circuitry (301, 302) or spare internal circuitry (511) of the processor to generate interrupts (406) or DMA requests that indicate to the processor or to a host interface (510) of the processor, which time slots to access. The processor has a read buffer (105, 505) and a write buffer (106, 506) for effecting data transfers between the TDM medium and the applications.

Abstract: The encoding/transmission of information in an OFDM system is enhanced by using complementary codes. The complementary codes, more particularly, are converted into phase vectors and the resulting phase vectors are then used to modulate respective carrier signals. The modulated result is then transmitted to a receiver which decodes the received signals to recover the encoded information.

Abstract: A multiple output dc to dc converter is described that has multiple regulated output voltages. This is achieved by using a common subcircuit in conjunction with multiple input subcircuits to power multiple output circuits. The common subcircuit is used with an input subcircuit to form a converter input circuit which with a corresponding output circuit produces an output voltage. Any number of input subcircuits can be used with the common subcircuit to produce a corresponding amount of output voltages. The multiple output dc to dc converter described produces output voltage of the same quality as using parallel converters but with a cost and complexity similar to that of using inferior secondary side switches for auxiliary outputs.

Abstract: A telephone base includes a base module and a rotatable base stand module. The base module may be elevated to a plurality of inclined positions by employing in the base stand modules the plurality of cantilever snap members each of which has a protruding locking member. The telephone base module includes a plurality of locking apertures which correspond to the locking members on the cantilever snap members. The desired inclined positions are obtained by rotating the base module around pivot elements in the base stand module and inserting the locking members on the cantilever snap members into appropriate ones of the locking apertures in the base module. Additionally, the base stand module may be rotated and locked in place to the base module by additional locking members to orient the telephone base for wall mounting. Advantageously all the elements required for the above features are integrally molded into the base module and the base stand module.

Abstract: A port circuit (108) for a time-division multiplexed (TDM) switching system (100) is designed to effect sub-time-slot operation without external support, as well as to effect conventional, time-slot operation. A clock-frequency multiplier, such as a frequency-multiplexed phase-lock loop (PLL 202), and a multiplier-driven sub-time-slot operation circuit, such as a PLL-driven finite state machine (203), are incorporated into the port circuit. The clock-frequency multiplier and the sub-time-slot operation circuit generate all the additional control signals that are necessary to define sub-time slots and to effect multiple information transfers in a single time slot. The port circuit engages in conventional time-slot transfers with conventional port circuits, whereby it is compatible therewith, and engages in sub-time-slot transfers with other sub-time-slot enabled port circuits, whereby it increases the transfer throughput of the TDM switching fabric.

Abstract: The first amplifier stage in the A/D converter receives an analog input signal and generates an analog residue signal and a digital output signal. Any other amplifier stage in the A/D converter receives the analog residue signal and the digital output signal from the previous amplifier stage, and generates another analog residue signal and another digital output signal. The comparator stage receives the analog residue signal and the digital output signal from the last amplifier stage, and generates one or more additional digital output signals. The digital output signals from all of the stages are used to generate the digitized equivalent of the original analog input signal. Because the comparator stage can be designed without an amplifier, the total number of amplifiers required to implement the A/D converter is reduced, as compared to prior art techniques.

Abstract: An equalizer/decoder for a communication channel presenting impairments to error-free reception of transmitted symbols includes a modified Viterbi decoder operating on samples of received signals in a plurality of equivalent subchannels. Estimates of each of the subchannels are updated using a locally best estimate in the Viterbi trellis processing, thereby avoiding delay in updating channel estimates in a rapidly changing channel such as a digital cellular communications channels. A leaky predictor channel updating technique also proves advantageous in an alternative embodiment.

Abstract: Simultaneous voice-and-data (SVD) modems (106, 156) are employed automatically in a call initiated between a telephone (111) of a remotely-serviceable communications switching system (101) and a telephone (161) of a service center (150) that includes either a maintenance and diagnostics system (165) or maintenance and diagnostics workstations (162). The remotely-serviceable communications switching system automatically connects the voice portion of a single SVD call set up by the SVD modem to its associated telephone and automatically connects the data portion of the SVD call to its remote maintenance and diagnostics port (109). An automatic call distribution (ACD) communications switching system (151) of the service center automatically connects the voice portion of the SVD call to a telephone (161) of one of its agents (163) and automatically connects the data portion of the SVD call to the maintenance and diagnostics system or workstation.

Abstract: An apparatus and method provides optical multiple wavelength signals using a single, broadband optical source such, for example, as an LED, to generate many independent optical wavelength channels. An optical transmitter includes a wavelength channel defining assembly which resolves the broad spectrum pulses output by the source into discrete wavelength bands constituting respective pulses (i.e., wavelength channels) and which inserts a delay between the bands to define a sequence of individually addressable channels.In accordance with one embodiment of the invention, spectral splicing is achieved by a multiple channel filter, and insertion of the respective delays is achieved by individual fiber sections, each section having a length selected to introduce a particular delay, coupled to the output ports of the router. The inserted delays can be conveniently selected to separate adjacent wavelength channels and thereby minimize the likelihood of crosstalk.

Abstract: An equalizer/decoder for a communication channel presenting impairments to error-free reception of transmitted symbols includes a modified Viterbi decoder operating on samples of received signals in a plurality of equivalent subchannels. Estimates of each of the subchannels are updated using a locally best estimate in the Viterbi trellis processing, thereby avoiding delay in updating channel estimates in a rapidly changing channel such as a digital cellular communications channels. A leaky predictor channel updating technique also proves advantageous in an alternative embodiment.

Abstract: A transformer (FIG. 1) optimized for surface-mount vacuum-pickup automated circuit assembly eliminates the expense of a transformer housing. The transformer has a ferrite body (100) that defines a pair of wells (208, 209) each opening onto an opposite face (108, 109) of the ferrite body. Transformer primary and secondary windings are wound in a coil (103) through slots (210, 211) around a transformer core (204) at the bottom of the wells. The windings do not protrude from the wells beyond the faces, resulting in flat faces. A first plurality of conductive vias (104-106), one pair for each winding, are completely embedded in the ferrite body and extend to both of the faces. Each pair of vias serves at one face to attach to the winding and at the other face to attach to solder pods of a PC board. The embedded vias also serve as EMI filters. A plate (107) covers the one face and provides a surface for vacuum pickup and for labeling of the transformer. The ferrite body (500) of a first transformer (FIG.

Abstract: A connector for optical fibers comprises a rigid plug formed from material molded around end portions of the fibers and a pair of hollow tubes. All the fibers and tubes extend along parallel straight lines and all the tubes and fibers terminate in a common external surface of the plug. Alignment pins disposed within and extending outwardly from the tubes are used to align the plug with an optical component also aligned by the guide pins. A method of fabrication uses an alignment block for precisely relatively positioning first portions of the fibers and tubes, but with second portions of the fibers and tubes extending beyond an end of the block. The extending second portions of the fibers and tubes, but not the first portions thereof, are encapsulated within a molded plug which is then severed from the fiber and tube first portions for forming the plug common external surface.

Abstract: In a capacitor microphone system for directional applications, an array of backplates of microphone cells are formed on a printed circuit (PC) board. A continuous strip of diaphragm is employed to cover each backplate. The diaphragm is stretched to create a uniform tension along its length, contributing to the objective of achieving a uniform gain by each microphone cell. In addition, the diaphragm is separated from the backplates by a relatively large distance such that the percentage deviation from such a distance from cell to cell is relatively small, again contributing to the objective of gain uniformity.

Abstract: The amplification of crosstalk between two isolated circuits due to a resonant condition between the two circuits is reduced by coupling the electrical grounds associated with the circuits with a series Resistor-Capacitor network.

Abstract: Disclosed is an optical and/or microelectronics hermetic package which includes a member for absorbing hydrogen from the internal package ambient. The member includes a first layer which forms a hydride and, formed thereover, a second layer which forms solvated hydrogen upon exposure to molecular hydrogen in the package. The second layer acts as a one way valve for transporting hydrogen to the first layer which locks up the hydrogen.

Abstract: A refractory dielectric body is heated with a plasma torch at conditions which do not result in substantial removal of a surface portion of the body, yet which are sufficient to reduce both surface and bulk impurities. Typically, the body is solid, e.g., a rod as opposed to a tube, and is treated with the plasma in the absence of simultaneous deposition of material onto the body. Advantageously, an isothermal plasma torch is utilized, and the torch advantageously produces an oxygen or oxygen-containing plasma. The invention is useful for reducing chlorine impurities by at least about 30% to a depth of at least about 10 .mu.m, with accompanying reduction of hydroxyl impurities. The invention thus provides a useful method for reducing the concentration of impurities that contribute to imperfections during the process of drawing fiber from an optical fiber preform, without requiring substantial removal of the surface of the preform.

Abstract: A method of and apparatus for effecting single sideband modulation which mixes and sums the quadrature and in-phase components of a baseband signal with the in-phase and quadrature components of an intermediate frequency (IF) signal to form in-phase and quadrature components of a sum signal having a frequency equal to the sum of the frequencies of the baseband and intermediate frequency signals and which mixes and sums the quadrature and in-phase components of an RF carrier signal with the in-phase and quadrature components of the sum signal to form a single-sideband signal.

Abstract: A control system for an converter circuit using two interleaved boost circuits is described which uses a single PWM controller to control the switches in both of the interleaved boost circuits. A voltage feedback control circuit monitors the output voltage of the converter circuit and sends that information to the PWM controller. A current sensing circuit is provided that senses the current in each of the boost converters. The current sensed in the current sensing circuit is converted to a voltage and used in conjunction with the voltage information from voltage feedback control circuit by the single PWM controller to regulate both of the boost converter switches. By regulating the boost converter switches, the single PWM controller is able to ensure proper synchronization and current sharing while tightly regulating the output voltage and improving the input power factor of the converter circuit.