Abstract: By introducing an asymmetry in the effective refractive index profile of a waveguide, wave energy can be extracted from the waveguide by radiation at wavelengths greater than a critical wavelength, where the latter is a function of the effective index distribution. This technique is employed to develop a variety of optical wavelength filters.

Abstract: A tracing facility which is useful in a multiprocessing environment on a single processor is disclosed. Tracing statements are encoded within each process, each statement having arguments to indicate its location in the code and a message which is logged when the sybsystem and function corresponding to that tracing statement are selected for debugging. Each process includes a trace library that is called by each trace statement, and the trace library includes a local sync word and a local trace table having a list of the subsystems and functions currently selected for tracing. Each process has access to a global sync word and a global trace table having a list of the processes, subsystems and functions selected for tracing. A change in the trace operation is made by changing a parameter in the global trace table and changing the value of the global sync word to indicate that a change has been made in the global table.

Abstract: The present invention relates to a phased array antenna system which transmits a local oscillator signal in a scanable spotbeam from a first array of feed elements (12.sub.l -12.sub.m) via a reflector or lens (16) and a frequency diplexing means (18) to a second array of feed elements (20.sub.l -20.sub.n) disposed on the image plane of the first array of feed elements. A message signal in a second beam also impinging the frequency diplexing means from a separate direction is also received at the second array of feed elements. The message signal and the local oscillator signal concurrently received at each of the feed elements of the second array are mixed in individual mixers and the output of each mixer can be reradiated for transmission to a remote receiver or combined with the outputs of the other mixers for use by a local receiver.

Abstract: Operation of a computer system after a main memory failure is enabled by storing a read-only access shadow copy of its data structures in another memory having an independent failure mode. The shadow copy is periodically updated at a series of checkpoints. Where the data structure is a linked list, updating without recopying is enabled by prelinking the list item in the read-only list to the beginning of a second read/write list, which is appended to the first list at the next checkpoint.

Abstract: Circuitry is disclosed for allocating requests for demand-sharing bus access among a plurality of service requesting ports. During bus contention time, each requesting port synchronously and sequentially applies the digits of its assigned unique priority code to the bus beginning with the most significant digit. After the application of all digits, only the requesting port having the highest code remains in contention and it seizes the bus. The present invention provides flexibility in port preference by the use of a plurality of status flip-flops in each port for generating dynamic port parameter bits. The generated parameter bits are normally applied to the bus as the most significant bits of a dynamic port priority code during contention time. The state of the status flip-flops is controlled by circuitry which counts the number of packets of a specified size currently stored in the buffer memory of each port.

Abstract: The present invention relates to a technique for enabling an antenna system to linearly scan over a wide angle of an orbital arc segment from a terrestrial ground station to access or track satellites within the segment. The wide angle linear scan capability is achieved by orienting the antenna system at the ground station relative to the local terrestrial coordinate system such that the axis normal to the aperture plane of the antenna system is at a predetermined angle and lies in a plane substantially parallel to the plane of the orbital arc segment. Then, by squinting the beam toward the orbital arc segment by applying a fixed linear phase taper to the antenna elements of a planar phased array along one axis of the array, linear scanning of the orbital arc segment is possible by, for example, varying the linear phase taper applied to antenna elements along another axis of the array.

Abstract: A carrier recovery circuit is disclosed for use in the receiver of a digital transmission wherein channels of data are formed by demodulating incoming quadrature-related carriers using receiver-generated, quadrature-related carriers. Phase alignment of the receiver-generated carriers to the incoming carriers is provided by integrated data from a preselected channel when the channels of data correspond to preselected regions in the signal space diagram.

Abstract: In a data processing system, the subject error correcting circuit is connected in the bridging mode to the data bus which interconnects a processor and a memory for error detection. It is presumed that the memory words obtained from the memory are relatively error-free, and the subject circuit does not delay their transmission, but simply monitors the data. If an error in the data is detected, an error signal is generated on the next processor microcycle, the processor aborts its present operation and then fetches the corrected data from the error correction circuit. If the frequency of errors increases or if a permanent error is detected, the subject error correction circuit switches to an in-line mode where it functions much as prior art error correction circuits: delaying the transmission of each memory word until the error check is complete.

Abstract: An n-dimensional channel code is used in a data transmission system. The alphabet of codewords (data symbols) comprises a subset of points of a selected coset of a selected lattice. The alphabet includes at least one point of the coset whose norm (signal energy) is greater than at least one other point of the coset which is excluded from the alphabet.

Abstract: There is disclosed an automated hardware inventory system for remote identification of system circuits. The system includes a central processing unit for addressing circuits over a bidirectional communication bus. A memory device and control circuitry is affixed to each circuit for the storage of information to identify each said circuit when addressed by the central processing unit. The identity information includes the vintage of the circuit.

Abstract: The present key telephone system comprises cordless telephone stations (FIGS. 6 and 7) which communicate over a line-of-sight transmission end link (276 or 277). The system further comprises a central controller (101) for switching communications between the cordless stations and to the message network. The central controller does not provide any station to transmission channel concentration. Concentration occurs in the bidding by a cordless station for access to a channel provided by the line-of-sight transmission end link. A particular number of transmission channels are provided by the line-of-sight end link which are bid for by any practical number of cordless stations. Subsystem controllers (104) are provided in a large cordless key telephone system. The subsystem controller reformats data for transmission between the central controller (101) and a cordless station.

Abstract: In a telephone conference system, a voice switching arrangement allows a speaker who has seized the line to hear and thus permit an interrupting speaker an opportunity to talk. This arrangement is achieved in a multiparty connection by using two complementary comb filter banks on a voice channel with the filter passbands of the first bank being stopbands in the second bank and vice versa. During the time when only one speaker is talking, a full voice channel is provided for the speaker. When an interrupting speaker also begins to talk, the first filter bank is inserted in the speech signal path of the speaker who has seized the line and the second filter bank inserted in the speech signal path of the interrupting speaker such that the first speaker and the interrupting speaker receive the other's speech signals.

Abstract: The present invention relates to a high speed optical switch and the use of such switches to form a time division demultiplexer. The optical switch comprises a length of linear material (12) including an outer surface on a portion of which is formed a layer of nonlinear material (11) to form a nonlinear interface (10) at the boundary of the two materials. An input data light beam (14) is propagated in the linear material with a predetermined intensity and angle of incidence on the nonlinear interface to, by itself, cause total reflection of the input beam. A control light beam (11) is also selectively energized and directed at the nonlinear interface with an intensity and angle of incidence to cause a portion of the input data beam to be formed into a self-focused channel or beam propagating in the nonlinear material. The self-focused beam can then be detected at an edge of the nonlinear material.

Abstract: The invention provides apparatus comprising at least two beams of coherent radiation directed so as to intersect and form a standing wave pattern having a period .LAMBDA. in an optically responsive medium. The optically responsive medium is a colloidal suspension of dielectric particles in a liquid medium, the dielectric particles and liquid having different indices of refraction, and the diameter of the particles being less than or approximately equal to the period .LAMBDA.. The dielectric particles are arranged into a grating by the electric fields carried by the beams of coherent radiation. In an embodiment of the invention, the dielectric particles are small dielectric spheres. The dielectric particles and the liquid may have approximately equal mass densities. A third beam of light may generate an output beam of light by degenerate four-wave mixing processes incorporating a dielectric grating made by the electric fields carried by the beams of coherent radiation.

Abstract: A method and circuitry are disclosed for asynchronously transmitting binary data over a communication pair without the use of start or stop bits. During a non-data transmitting state a quiescent differential voltage, which is intermediate to the binary data differential voltage levels, is placed on the pair. The start of a data transmission is signaled by a transition of the differential voltage from the quiescent state voltage to the binary voltage of the first data bit of the data transmission. Since all data transmissions are of known bit lengths, the end of a data transmission is determined by counting data bits.

Abstract: The disclosed operational amplifier comprises a first pair of complementary type transistors (Q5, Q6) (of high current carrying capacity) that have their emitter-collector paths connected in series across a source of reference potential. The emitters of the transistors are connected together and to an output terminal (17). A second pair of complementary type transistors (Q3, Q4) are coupled across said reference potential, each transistor of said second pair being coupled across the similar conductivity type transistor of said first pair. A first pair of resistances (R1, R2) of predetermined value are respectively connected between the bases of the similar conductivity type transistors of said first and second pair. A second pair of resistances (R3, R4) respectively connect the emitters of the transistors of said second pair to said output terminal.

Abstract: A technique for processing pictorial information to enable its display on a desired display device independent of the latter's resolution characteristics includes a unique encoding procedure and a corresponding decoding and display procedure. Attributes of each element of a picture or image (such as its color) are specified by a group of N bits. The bits are assembled to form M-bit active portions of a series of bytes. M and N need not be integrally related. Ones of the words also define the size of the elements with respect to a unit display space (the horizontal and vertical dimensions of each element can be different), the order in which the elements are arranged in the picture (e.g., left to right or vice versa) and the value of N.

Abstract: The flicker which results from large intensity differences in adjacent scan lines of a symbol displayed in an interlaced-field format is reduced by a non-linear signal filter and signal generator. The disclosed filter and signal generator changes the intensity of a scan line adjacent to a scan line of a symbol in response to a detected predetermined intensity difference between the adjacent scan line and the symbol scan line.