Abstract: A packet switching network that accommodates the appearance of multiple occurrences of packets addressed to the same destination are accommodated. The network includes a recirculating delay block within the switch, and an expander that includes a modest number of multiple appearances of the same address, followed by memories that accept the packets delivered at those multiple appearances, store the packets, and output the stored packets to the user, one at a time, in accordance with a set priority scheme.

Abstract: An electrical device is provided which has contacts having regions with a conductive matte-finish metal surface. The matte-finish surface is characterized by having a Knoop hardness number of at least 300, a diffuse reflectance of less than about 20 percent, and a specular reflectance of less than about 2 percent. These contacts have a contact resistance of less than about 50 milliohms, under a 50-gram load, even after exposure to 50.degree. C. and 95% relative humidity for a period of 20 days. Reflection electron microscopy shows that particularly advantageous matte-finish surfaces have sharply peaked asperities with average peak angles of less than about 90 degrees. In one embodiment, the surface is formed of hardened nickel electroplated from an electrolytic bath with a pH above about 7.0.

Abstract: A power inverter efficiency is optimized at high frequency in a fully resonant inverter operating with a range of load impedance that takes into consideration switching loss and conducting loss as a combined overall effect. Within this range of load impedance the inverter is constrained to operate with switching loss which is generally considered unacceptable in a conventional high frequency high efficiency power inverter, but the overall combined high efficiency of the disclosed power inverter has a wider range of load impedances than has been previously achieved in such a resonant power inverter. Non-linear capacitance across switching the device is positively utilized in achieving this goal.

Abstract: A system for communicating a wide band signal across a plurlaity of narrow band channels by separating the wide band signal into two or more narrower sub-bands and modulating the developed narrower sub-bands down to baseband. The baseband channels are algebraically combined to form unique combination signals, and the combination signals are transmitted over the narrowband channels. On the receiving end, the combination signals are algebraically combined to recreate the original baseband channels. The channels are modulated up to their original frequency bands, and arithmetically combined to recreate the desired broadband signal.

Abstract: A rib waveguide polarization modulator is described that permits easy application to monolithic optical circuits. The device comprises a rib waveguide having two polarization modulation sections with a phasing section between the two modulation section. The phasing section adjusts the phase of the optical radiation in the waveguide before it enters the second modulation section.

Abstract: An input and output system has a plurality of tape drives (1-3) connected by a daisy-chained bus (5) to a processor (4). Each of two tape drives (2, 3) at the end of the bus has a terminator (30, 31) for transmit lines (6) of the bus. Each terminator of each line comprises a pull-down resistor (40) connecting the line to ground, and a pull-up resistor (41) and a diode (42) in series connecting the line to a source of potential (43). When a source is powered up, potential is present and a diode connected thereto is forward biased and supplies potential to the line. When the source is powered down and potential is withdrawn, a diode connected thereto becomes reverse-biased and prevents the powered-down source from grounding the line. Redundant termination of each line therefore allows any one tape drive to be powered down without precluding communications over the bus from continuing while the other terminator continues to supply the line with potential.

Abstract: The system (10) provides a way of utilizing announcement distribution service equipment (21) which is presently in use in telecommunications networks (20) for ordering television or other signals (23) on a per program basis. The program signals (23) are enciphered. The receiver (30) is connected to receive a deciphered signal from a subscriber deciphering unit (18) at a subscriber location. The subscriber unit (18) is connected to the telecommunications network (20) by a nondedicated telephone service line (28). In response to an order instruction by the subscriber, the unit (18) automatically calls the appropriate announcement distribution service number for the channel associated with the desired program signal and receives from the service the coded key information (58) necessary for it to decipher the program signal. When the program signal is received by the unit (18), it is accompanied by control signals during retrace intervals which activate deciphering circuitry (G) in the unit.

Abstract: A speech analysis and synthesis system where pitch information for excitation is transmitted during voice segments of speech and pulse excitation or noise excitation is transmitted during unvoiced speech segments along with linear predictive coding (LPC) parameters. The decision of whether to transmit noise excitation or pulse excitation is performed by comparing the variance of the residual to the square of the mean amplitude of the rectified residual for each frame. If the result of this comparison is greater than a threshold value, pulse excitation is utilized otherwise noise excitation is used. The pulse excitation comprises a subset of samples of the LPC residual as determined by the relative amplitudes and spacing of the local maxima in the LPC residual.

Abstract: An article of manufacture comprising an electron device encapsulated by a silicone resin material consisting essentially of 15 to 30 weight percent of polydimethylsiloxane and/or polymethylphenylsiloxane resin including a platinum catalyst, 50 to 80 weight percent of silicon dioxide and 5 to 20 weight percent of a silicon hydride.

Abstract: High resistivity In-based compound Group III-V epitaxial layers are used to prevent substantial current flow through a region of a semiconductor device, such as a CSBH, DCPBH, EMBH or CMBH laser, a LED, a photodiode, a HBT, or a FET. Also described is a hydride VPE process for making the high resistivity material doped with Fe. The Fe is supplied by a volatile halogenated Fe compound, and the extend of pyrolysis of the hydride is limited to allow transport of sufficient dopant to the growth area.

Abstract: A method for fabricating a polarization rotator which includes a thin film waveguide exhibiting essentially zero linear birefringence in the absence of an externally applied stress, as well as an optical system incorporating said rotator, is disclosed.

Abstract: Maximum frequency range in a VLSI voltage controllable crystal oscillator is obtained with a two-stage amplifier with feedback across both stages. The first stage is implemented by an MOS transistor connected in source-follower configuration to minimize input capacitance, and the second stage is implemented by a bipolar transistor to provide the needed gain. A bidirectional voltage limiter connected to a crystal node limits the oscillations to a symmetrical waveform. The bias of an output buffer amplifier may be selectively shifted to maintain optimum duty cycle with the different triggering levels of diverse logic driven by the oscillator, and the bias may be dynamically driven by an analog signal to provide a duty cycle-modulated output.

Abstract: An electrical calibration circuit in a voice switched adaptive speakerphone accurately determines the operating parameters of the speakerphone for optimal performance before operation. This is achieved by updating thresholds used to determine when the speakerphone should be in each of three possible operating states; transmit, receive or idle. During operation, these thresholds are compared with transmit and receive signal strength levels to determine the state of the speakerphone. The thresholds are updated to counteract the effects of variation and aging of hardware circuits in the speakerphone and are obtained by having the calibration circuit generate a test tone signal which is passed through speech processing circuitry in the speakerphone at two different levels and the resulting response measured.

Abstract: Silicides are important for submicron VLSIC technology. Problems have been found in forming silicides by known techniques involving simply depositing a metal film and heating that metal to form a silicide layer. This invention solves the problems through recognition that polymeric contamination can be left on the surface from commonly-used previous reactive ion etch steps, and removes any such contamination to metal deposition by the additional step of heating in dry oxygen at a low temperature, such as 800 degrees Centigrade, before the contamination has been significantly hardened.

Abstract: A fast pipeline adder comprising a plurality of registered adder rows. In one embodiment, additions in the pipeline are realized in reclocked half adders. In another embodiment, modified adders are employed which accept two carry inputs and develop two carry outputs. The resulting number of individual cells is reduced to approximately half of those in the prior embodiment. In still another embodiment, switch means are included in each cell to delete the reclocking and in still another embodiment, the adders in the diagonal of the pipeline adder are provided with additional inputs to permit use of the pipeline adder in recursive addition applications. In still another embodiment, the cells are permitted to output the inverse of the intended signal, reducing thereby the physical realization of the cells and increasing the speed of the cells.

Abstract: A self-aligned one transistor-capacitor memory cell is provided which uses an n-channel MOS transistor having separate drain and source regions with a first level polysilicon conductor coupled to the top plate of the capacitor and separate second level polysilicon conductors coupled to the gate and drain of the transistor. A reduction in a dimension of the memory cell is acheived compared to a similar memory cell which uses only one level of conductors.

Abstract: Modems, data service units, application modules and other data communication devices, installed in a common equipment cabinet, are interconnected by way of a time division multiplexed bus. Time slots assigned to the various devices recur at a number of rigidly-spaced access periods across each time division multiplex frame. The rate at which the access periods occur and the total number of access periods that make up each frame are chosen in such a way as to accomodate a mix of devices having respective bus access rates wherein there is at least one pair of rates for which neither rate of the pair is a multiple of the other. The process of allocating access periods to the time slots is carried out using a known lemma to identify linear Diophantine equation solutions.

Abstract: In a voiceband data multipoint network, each tributary modem transmits, in a trailer which follows the user data, a tributary modem identification, a sequence number which advances for each start-up and a checksum. The observation at the receiver of a gap in the series of sequence numbers in messages determined to have originated from a particular tributary modem is used to accurately compute a missed message rate for that modem.

Abstract: Method and apparatus are disclosed for establishing a wideband communication facility from a plurality of narrow bandwidth channels through a switched communications network from a first to a second terminal in response to a call from the first terminal indicating a customer-selected bandwidth for the wideband facility. Apparatus is also disclosed for establishing a wideband communication path through an illustrative switching system interconnecting groups of narrowband time division multiplexed channels established for the wideband facility. The path has a bandwidth greater than any of the TDM channels. Additional buffer memories and memory control arrangements are added to the initial and final stages of a time-space-time switching network to prevent any of the time slot data of a given time frame from being delayed and included in another time frame.