Abstract: A polarization insensitive optical device is disclosed which is capable of providing direct optical amplification of an input signal of unknown (and possibly varying) polarization. A polarization diversity technique is utilized wherein a polarization beam splitter is used to divide the incoming signal into orthogonal components of known polarization (TE,TM). The orthogonal components are then separately amplified, using a semiconductor laser as the amplifying device. The amplified components are then recombined, either optically or electrically, to form the final output signal.

Abstract: An arrangement for securing data transmissions to and from one data device from among a plurality of data devices sharing a common interface is disclosed. In a data communication network, a master communication bus connects to a plurality of data transmitting and receiving devices via a single interface. The disclosed arrangement provides circuitry in the common interface which generates a jamming signal to all devices connected to the interface except for that one device which is either transmitting or receiving a data-transmission. The jamming signal inhibits all the connected devices from monitoring and detecting the data transmission processes of the interface. The one transmitting and receiving device is enabled to either transmit or receive data during the generation of the jamming signal which ensures a secure data transmission and prevents "eavesdropping" by the other devices. The jamming signal is removed at the conclusion of the data transmission to or from the one device.

Abstract: In a time division multiple access satellite communications system having a master station and one or more remote stations, frequency offset through the translation oscillator in the satellite is corrected by transmitting a pilot frequency signal, reference to a high precision oscillator, through the satellite, so as to subject the pilot frequency signal to a frequency translation and monitoring the frequency translation of the pilot frequency signal as received at the master station subsequent to its transmission through the satellite. Signals to be transmitted over the satellite communications link from the master station to remote stations are subjected to a frequency translation that is effectively complementary to the monitored frequency translation.

Abstract: A discrete event simulation system that avoids all blocking and advances the simulation time in an efficient manner by treating the simulated system as a set of subsystems and simulating the subsystems concurrently. The simulation proceeds iteratively by restricting the simulation of scheduled events for each subsystem at any one time to a chosen simulated time segment (bounded lag) beginning with the lowest simulation time found among the subsystems. With each simulation iteration, an "at risk", demarcation time is evaluated based only on a subset of the subsystems that can potentially affect the simulation at the considered subsystem. Events scheduled for a time earlier than the "at risk" time are simulated.

Abstract: A biconic optical fiber connector (20) comprising two plugs (24--24) each having truncated conically shaped end portions (30--30) for terminating optical fibers to be connected and a sleeve (66) in which the plug eng portions are received is provided with an attenuator (70) which results in low reflected power. The attenuator comprises a plate-like element which is disposed between the plug end portions. Advantageously, the plugs are seated in the sleeve and the thickness and mounting of the attenuator cooperate to cause the plug ends to engage the attenuator when the plugs are seated in the sleeve cavities. Also, the attenuator is supported within the sleeve so that it is capable of slight movement in a direction parallel to a longitudinal axis (91) of the sleeve to self-adjust, if necessary, as the plug end portions are inserted and become seated in the sleeve.

Abstract: Disclosed is a dense channel packing wavelength division multiplexed optical fiber communication system that is parsimonious in its cable length requirements and that does not require the presence of widely tunable lasers at the remote terminals. The system comprises a central station and N remote stations (N frequently greater than about 50) connected to the central station by optical fiber means that comprise a "backbone" and l (1<l<N) fiber "laterals". Associated with each remote station RS.sub.i is a predetermined wavelength .lambda..sub.i, typically in the spectral region 1.25-1.6 .mu.m. The central station comprises means adapted for generating electromagnetic radiation of a multiplicity of distinct wavelengths including all .lambda..sub.i. The radiation from the central station is coupled into the backbone fiber and transmitted to the laterals and the remote stations. Each remote station RS.sub.i comprises means for selecting the radiation of the associated wavelength .lambda..sub.

Abstract: The present invention relates to a transition wherein a microstrip line, formed on one major surface of a substrate, is capacitively coupled to a reduced-height waveguide, comprising a predetermined width-to-height ratio, by means of a T-bar conductive pattern formed on a substrate at the end of the microstrip line. Such T-bar transitions can also be connected on opposite end of the microstrip line to provide connections between two waveguide sections.

Abstract: In a data transmission system using a predetermined trellis code, the output signal points are selected from a predetermined alphabet representing (k+n)-bit input words by using the values of n bits of each input word, and bits from previous input words, to identify a particular one of 2.sup.m subsets of the signaling alphabet m>n. The other k bits of the input word identify an ensemble of four signal points of the identified subset. This ensemble is characterized by having a first signal point whose odd components and even components each sum to a value no less than zero, a second signal point whose odd components sum to a value no less than zero and even components a value no greater than zero, a third signal point whose odd components sum to a value no greater than zero and even components a value no less than zero, and a fourth signal point whose odd components and even components each sum to a value no greater than zero.

Abstract: An apparatus for testing of electrical circuits has a buckling beam probe assembly having advantageous features that make it useful for contacting area arrays of test points, and for reliably establishing contact therewith. The probe elements remain essentially parallel even in the buckled state, and the probe tips execute a small "wiping" movement on the contact point. In some preferred embodiments the probe tips are shaped to result in reduced contact area.

Abstract: Personalized telephone features are made available to subscribers away from their home base. A nationally accessible data base system stores feature data in association with personal identification numbers. A subscriber wishing to use personalized features while away from the home base dials a special code from a station connected to any exchange which has access to the data base and presents the personal identification number. The corresponding feature data is retrieved from the data base and stored in the exchange in association with the station from which the request was initiated and telephone service will be rendered in that exchange with the subscriber's personalized telephone features. A temporary office arrangement may be established in which the personalized features will be immediately available on incoming and outgoing calls for a period of time specified by the subscriber. In one embodiment the feature data is stored on a credit card and transmitted to the exchange by a card reader.

Abstract: The names in a directory stored in a personal terminal having a display are displayed as groups of names in which illustratively the first name in each group of names serves as a displayed tab which is pointed to by the user to display the respective group of names. The individual tabs are dynamically changed to conform with any change in the first name of the respective groups of names that may occur as a result of a change in the composition of the directory.

Abstract: A method and apparatus for processing operator assistance calls with minimum expenditure of operator work time. For collect and person-to-person calls, a first operator at a first operator position determines the type of call and, optionally, the name(s) of the calling and called parties. These are recorded in the memory of a program controlled processor system for controlling an operator assistance switching system. The first operator then disconnects from the call while the call is being set up and the call party being alerted. When the called party answers, a second operator position and second operator, having a display of the call information previously recorded, are unattached to the call to determine whether a connection between the calling and called parties should be established and, if so, to cause that connection to be so established.

Abstract: A high capacity metropolitan area network (MAN) is described. Data traffic from users is connected to data concentrators at the edge of the network, and is transmitted over fiber optic data links to a hub where the data is switched. The hub includes a plurality of data switching modules, each having a control means, and each connected to a distributed control space division switch. Advantageously, the data switching modules, whose inputs are connected to the concentrators, perform all checking and routing functions, while the 1024.times.1024 maximum size space division switch, whose outputs are connected to the concentrators, provides a large fan-out distribution network for reaching many concentrators from each data switching module.

Abstract: A non-invasive optical fiber coupler for coupling light into an optical fiber bus through the cladding surrounding the optical fiber bus without bending the optical fiber bus. The coupler comprises a tap optical fiber free end adjacent to and facing a region of straight optical fiber bus with the tap fiber free end and optical fiber bus region encapsulated with a junction media having substantially the same index of refraction as the cladding of the optical fiber bus. Since the bus cladding is not removed nor is the optical fiber bus bent, there is no additional light lost due to the coupler from the optical fiber bus.

Abstract: A general purpose computer test interface is used to test various types of computers having differing input/output characteristics. The interface comprises a control unit which is responsive to messages from a controlling host computer to generate a unique set of type control signals for each computer type to be tested. Interfce control logic circuits combine the type control signals with bus control signals from a target computer under test to adapt the interface for communication with each of the different types of targets defined by the type control signals.

Abstract: Apparatus for encoding speech using a code excited linear predictive (CELP) encoder using a recursive computational unit. In response to a target excitation vector that models a present frame of speech, the computational unit utilizes a finite impulse response linear predictive coding (LPC) filter and an overlapping codebook to determine a candidate excitation vector from the codebook that matches the target excitation vector after searching the entire codebook for the best match. For each candidate excitation vector accessed from the overlapping codebook, only one sample of the accessed vector and one sample of the previously accessed vector must have arithmetic operations performed on them to evaluate the new vector rather than all of the samples as is normal for CELP methods. For increased performance, a stochastically excited linear predictive (SELP) encoder is used in series with the adaptive CELP encoder.

Abstract: Disclosed is an optical fiber connector useful for high density arrays. A locking collar is mounted near the rearward portion of a fiber ferrule. The collar includes tabs which engage holes in the connector sleeve when the ferrule is inserted therein. The fiber can be inserted and removed by a tool which depresses the tabs. Space is conserved since the locking mechanism is located entirely within the sleeve.

Abstract: A call announcement arrangement that obtains the calling party name from a database search and uses a text-to-speech unit to generate speech signals for transmission to the called communication station. The calling party name is spoken at the station instead of being displayed. For a conventional analog station, the name is spoken after the called party has answered in response to ringing at the station but before a connection is completed to the caller. The called party accepts the caller either by remaining off-hook or by transmitting a connection signal using, for example, flash or tone signaling. For other illustrative station equipment such as an ISDN speakerphone or a specially adapted analog speakerphone, the calling party name is spoken before the called party answers in place of or in addition to normal ringing. Caller-identifying speech signal are also transmitted to a station determined to be busy to announce the caller name for a call waiting call.

Abstract: A network architecture of the sort-then-expand type for routing packets including destination information is disclosed. The network includes a distribution stage comprising a plurality of input sorts units, an intermediate stage comprising a plurality of intermediate sort units and an output stage comprising a plurality of output switches. The input sort units each distribute a plurality of packets to the intermediate sort units such that each intermediate sort unit receives approximately the same number of packets destined for each output switch as the other intermediate sort units. Each intermediate sort unit identifies packet groups for a common output switch and connects the groups to the destination output switch. Each destination output switch merges the received groups of packets and distributes them to output ports.

Abstract: An optical fiber cable (20) which may be used in a high temperature environment for a substantial period of time without degradation of transmission includes an optical fiber core (22) which is enclosed by an inner tubular member (32) having suitable temperature resistant properties. A braided metallic outer tubular member (50) encloses the inner tubular member and provides suitable mechanical protection and strength for the cable. The integrity of the cable and its performance is further enhanced by a corrugated metallic tube having a sealed periphery and being interposed between the inner and outer tubular members to prevent the ingress of liquid contaminants and to provide the cable with flexibility.