Abstract: In a speech signal recognition system, signals are data-reduced by eliminating highly-transient intervals: each successive time frame is temporarily identified as an anchor frame and compared to m preceding and m succeeding frames, whereby defined uniform time intervals of 2m+1 frames having a prescribed similarity are retained, and highly-transient 2m+1 intervals are discarded.

Abstract: The present invention relates to a wideband communication network using wireless radio transmissions either on a stand-alone basis or to supplement a hard-wired network. The exemplary network comprises (a) a plurality of transceivers associated with separate users of the network; (b) optionally at least one concentrator associated with certain separate subgroups of wireless and possibly hard-wired transceivers for providing duplex operation; and (c) a central node (i) capable of providing both duplex communications directly via a radio channel using radio links with certain subgroups of the transceivers and via a hard-wired connection with each optional concentrator, and (ii) for polling the needs of all transceivers and directing all packets of information from active transceivers through the central node and to the destined transceivers during each frame period.

Abstract: The present invention relates to a switching technique for packet Frequency Division Multiplexed (FDM) communication systems. In the present system, each of N system users is assigned (a) either a separate fixed one of N transmit frequency channels or a selected free one of L transmit frequency channel for communications to a head-end FDM channel switching arrangement (IO), and (b) a fixed assigned separate one of N receive channels for communications from the head-end FDM channels switching arrangement. At the FDM channel switching means, all FDM channel signals received from the system users are directed into separate paths (21) through the switching arrangement. The signals in each path are demodulated (23) to baseband, and a destination address in each packet is detected (28) to determine where each packet is to be sent.

Abstract: A high data rate multiplexer (MUX) architecture includes front-end and rear-end MUXs clocked at a system clock rate equal to one-half of the MUX output data rate. The front-end MUX selects inputs under control of select signals derived from multiple phases of a select clock. The select clock is derived from the system clock. The number of select signals is equal to the multiplexing factor of the MUX.

Abstract: A non-destructive double exposure method of examining photoresist features in section by, e.g., scanning electron microscopy, is described.

Abstract: Optical switch networks and the design rules for creating them are disclosed. The networks comprise a plurality of input and output stages of optical switch elements. Each input optical switch stage is comprised of a plurality of 1 by 2 optical switch elements and each output stage is comprised of a plurality of 2 by 1 optical switch elements. Using these stages, optical switch networks are constructed where switch elements are interconnected by optical waveguides diffused in a substrate. Further, the connections between adjacent stages include optical waveguide crossovers (crossthroughs).

Abstract: A star coupler for a single-mode-fiber optical local area network which reduces the amount of fiber required by a factor of two and diminishes the number of components by one-half. This savings in fiber and components is effected by "reflecting" signals which appear at various locations of the network back toward the input ports. The arrangement forms a broadcast-type of local area network where a message transmitted by any user can be received by all users.

Abstract: An optical system is disclosed which includes at least a first source of electromagnetic radiation (signal beam radiation), a device for processing the signal beam radiation, and a detector for detecting the processed signal beam radiation. The processing device functions, for example, as an amplitude modulator, a demultiplexer, or a switch, and includes a material region exhibiting a nonlinear optical response at one or more resonant wavelengths of electromagnetic radiation, as well as at least a second source of electromagnetic radiation (control beam radiation) for selectively inducing the nonlinear optical response. Significantly, the wavelength, duration and intensity of the control beam radiation are chosen to induce a resonant, nonlinear optical response, essentially free of any relatively slow component, in said material region at repetition rates higher than about 1.25.times.10.sup.4 Hz, or higher than about 3.3.times.10.sup.10 Hz, or even as high, or higher, than about 2.5.times.10.sup.11 Hz.

Abstract: A succession of (k+n)-bit input words are coded for transmission over a (1 - D) partial response channel by applying n of the bits of each word to a trellis coder which, in turn, selects one of a plurality of 2.sup.m cosets from a predefined lattice, where M>n. A signal point, or "seed," is then selected as a function of both (a) the values of the other k bits and (b) the value, referred to as the "channel state", of the last pulse in the previous signalling interval, in such a way as to ensure that the signal point presented to the receiver is a point in the selected cost. Viterbi decoding on the cosets is then used in the receiver to recover the most likely sequence of transmitted signal points and, in turn, the (k+n)-bit input words.

Abstract: A duplex optical fiber connector (20) includes a housing (21) having a cable entrance end and a plug end. At the cable entrance end, an optical fiber cable (23) which includes two individually buffered optical fibers (25--25), strength member yarn (29) and a plastic jacket is routed into a flanged end of a bushing (45) having a tapered passageway therethrough. The bushing is supported in a base (22) of the housing. The jacket is removed from the portion of the cable which extends from the cable entrance end to the plug end and the yarn is positioned between two conformable, truncated conically shaped, substantially smooth surfaces which define the passageway of the bushing and a truncated conically shaped wedge (50) which is received in the passageway. The wedge includes a bore through which the optical fibers extend. This locking arrangement in which the yarn makes no retroflexed turns is self-enhancing when tensile forces are applied to the cable.

Abstract: An optical device comprising an optical waveguide having a varying refractive index has low radiation loss. The waveguide may be either curved or tapered.

Abstract: In an automatic call distributor system, calls waiting in a queue to receive attendant service are informed of the expected waiting time prior to connection to an attendant. This permits callers to defer a call if the queue is excessively long and they can place the call at a later time. The announcements are periodically updated to reassure customers that they are, in fact, progressing in the queue. Customers are given the opportunity to leave a message such as a telephone number if they do not wish to wait. Advantageously, such an arrangement avoids a situation wherein a customer impatiently disconnects just before being served or waits too long unexpectedly because of absence of information on remaining waiting time.

Abstract: An improved differential input amplifier stage used as the input stage in digital differential line receives or operational amplifiers. The differential input amplifier stage has a pair of input transistors forming a differential pair with a common output node and two complementary output nodes; a current mirror, coupled to the two complementary output nodes and responsive to a first one of the two complementary output nodes and a single-ended output signal on the second one of the two complementary output nodes; and a current source transistor coupled to the common output node and responsive to the first one of the two complementary output nodes. The current source transistor maintains the voltage on the first one of the two complementary output nodes substantially constant, thereby improving common mode and power supply noise immunity and providing faster differential response by the differential input amplifier stage.

Abstract: A data bus having a given size (e.g., 32 bits) provides for transfer of information between various logic and memory elements within, or among, one or more integrated circuits. Certain of the information transfers require the full information path, while others use only a portion (e.g., 8 or 16 bit transfers). To expedite the transfers of the smaller size words, a given word is replicated to fill up the full data base. This avoids the necessity of specifying the exact location of the smaller word on the data bus.

Abstract: The target of a color CRT includes a plurality of color stripe triads which are oriented on a (111) surface parallel to the <112> crystallographic direction. The pattern of the stripe triads is etched using a SiO.sub.2 etch mask deposited directly on the YAG and an etchant comprising a hot mixture of sulfuric and phosphoric acids.

Abstract: High-power, single transverse mode laser operation is achieved in an extended-cavity structure by combining a semiconductor gain medium having a large optical cavity together with a length of single mode optical fiber between first and second reflector surfaces. The first reflector surface is formed on an end facet of the semiconductor gain medium; the second reflector surface is formed on an end of the optical fiber. Output power is efficiently coupled from the fiber end of the extended-cavity laser to a standard transmission medium.

Abstract: The present invention relates to an antenna comprising a plurality of feeds, and either a single reflector or a single lens wherein the reflector or lens includes a predetermined curved major surface that produces a maximum field of view in a first one of two principal planes of the antenna. The major curved surface is designed to produce a first and a second "stigmatic" focal point, which are spaced apart by a predetermined amount on either side of an axis normal to the center of the reflector or lens in the first principal plane, such that the coefficient of astigmatism is at a maximum predetermined tolerable amount at the center and at the opposite edges of the maximum field of view to produce a peanut-shaped area where the coefficient of astigmatism is within tolerable limits.

Abstract: In a local data distribution network configuration a plurality of bidirectional data distribution busses are each connected to a bus master control circuit at a terminal end of the bus. Connected to each of the data distribution busses are a plurality of passive outlets to which intelligent connectors or stations may be connected. Each station has a unique address and is utilized for individually coupling data processing devices to the bus. Grouped pluralities of the bus master control circuits are included within a bus termination hub facility. Data from any of the bus master control circuits may be transferred by the bus termination hub via a data trunk as part of a star type configuration, to a central switching circuit such as a virtual circuit switch. Direction of data flow on each of the bidirectional busses and periodic temporary synchronization of the stations is controlled in response to signals transmitted to the bus by the bus master control circuitry associated with that bus.

Abstract: A method of fabricating a field-effect transistor is disclosed wherein only two masking steps are used in the development of the device. The semiconductor wafer used in the process has a non-alloyed contact at its top surface, that is, a contact which does not require alloying temperatures in excess of 200 degrees C. The first mask is used to create conventional mesa structures which isolate each individual field-effect transistor from its adjacent neighbors. A second mask is utilized to define the source and drain electrodes and also to create a gap through which the gate electrode structure is fabricated. By using a single mask for creation of both the source and drain electrodes and the gate structure, very close tolerances are obtained between the gate structure and the source and drain regions.

Abstract: The presence of material deposited on the sidewall during device fabrication utilizing plasma-effected etching of semiconductor materials has significant consequences in the properties of these devices. It has been found that such depositions lead to a sidewall slope that, among other things, in turn produces linewidth loss. Additionally, the presence of a sloped masking material, e.g., a photoresist or sidewall deposit, produces further undesirable results.