Abstract: An inter-frame encoding/decoding equipment for television signals consists of inter-frame encoding equipment encoding a difference between television signals and the output of a frame memory and inter-frame decoding equipment which receives an encoded signal sent from the inter-frame encoding device via a transmission line, which decodes by adding the output of the frame memory to the encoded signal. The inter-frame encoding equipment is provided with a first operation circuit which operates the remainders obtained by dividing, by a predetermined value, the number of bits of logic "1" in the bit groups into which the output or the input of the frame memory is divided by a predetermined unit. The inter-frame decoding equipment is provided with a second operation circuit which operates the remainders obtained by dividing, by a predetermined value, the number of bits of logic "1" in the bit groups into which the output or the input of the frame memory is divided by a predetermined unit.

Abstract: This invention relates to a method of switching voice and data over a multistage interconnection network (MIN). More specifically, a plurality of bits are stored in respective storage locations of the switching elements of the MIN. Storage location of a switching element represents a particular time slot in a frame or a sequence of frames. Bits stored in each location represent specific conditions of the inputs and outputs of the switching elements and also indicate which inputs of the switching elements will be connected to which outputs of the switching elements. This storage of control information in the switching elements allows the switching network to rapidly and simultaneously change connections through the switching elements of the network.

Abstract: Optoelectronic switching matrix which switches multiplexed input signals to narrowband output lines. Each crosspoint of the matrix is comprised of a heterodyning photosensor, which optically receives the multiplexed input signal and electrically receives a selectable local oscillator signal. The difference frequency can thus be selected to be within the passband of a low pass filter whereby narrowband output signals can be received from the input signals without requiring the use of a demultiplexer.

Abstract: A dispersion transformer for limiting the data rate of an optical fiber transmission system. A transmission optical fiber, which connects a transmitter and a receiver, may have a bandwidth much greater than that necessary to transmit a desired predetermined maximum data rate. The transmitted signal is connected to wavelength disperser means which spatially separates the different wavelength components of the transmitted signal. Each wavelength component is then propagated with a different delay by optical fiber delay means. The wavelength component which propagates with the least delay through the transmission optical fiber is subjected to the least induced delay in the optical fiber delay means and that which propagates with the greatest delay through the transmission optical fiber is subjected to the greatest induced delay in optical fiber delay means, the remaining components being subjected to intermediate delays. The delayed wavelength components are combined to form a series of broadened optical pulses.

Abstract: An optical communication processs is capable of avoiding errors resulting from stray reflection of the transmitted optical signals. For this purpose, the optical receptor of an apparatus is disabled during the transmission of optical signals from the optical transmitter of this apparatus.

Abstract: A method and associated system for providing multi-channel transmission of digital and broadband video information in optical fiber communication for local area networks through frequency-division-multiplexing, comprising the steps of generating a plurality of closely spaced optical carrier wave pairs with the optical carrier waves within each optical carrier wave pair having a predetermined separation frequency between one another, assigning each of the plurality of optical carrier wave pairs to a predetermined frequency slot and optically combining the plurality of optical carrier wave pairs to provide a multiplexed optical output wave. Advantageously, in addition to direct detection the plurality of optical carrier wave pairs may be detected by opto-electronic heterodyne detection and/or incoherent optical-heterodyne detection to electronically recover the optical carrier wave pairs.

Abstract: An arrangement for optical multiplexing and demultiplexing. The multiplexer comprises an optical output waveguide and a plurality of optical input waveguides coupled to the output waveguide by nonblocking optical switches. An electrical activation signal at a switch causes light entering the switch through the associated input waveguide to appear on the output waveguide. The activation signals are provided by a pulse traveling down an electrode past the optical switches, such that parallel input signals on the input waveguides are time multiplexed onto the output waveguide to produce a serial output signal. A similar arrangement is provided for a demultiplexer comprising one input waveguide and a plurality of output waveguides.

Abstract: An optical communication system suitable for wide area communications includes a plurality of local networks each having a communications bus and a plurality of terminal devices coupled to the respective local network communications bus for intranetwork communications with other terminal devices within the local network or internetwork communications with terminal devices in other local networks. Each terminal device includes a channel selecting device for selecting one of a plurality of frequency distinct communication channels. Each local network is assigned a common set of communication channels for communications within the local network and also assigned a unique subset of communication channels for internetwork communications. Each local network is coupled to every other local network through a frequency selective coupling means that passes only information signals at frequencies corresponding to the unique subset of communication channels for that local network.

Abstract: A video coupler device capable of providing high effective electrical isolation between an analog video signal source system and a signal receiving system is disclosed. The device includes a high-speed LED and a high-speed, linear, integrated circuit. The integrated circuit includes a photodiode, an input current amplifier and an output transimpedance amplifier. The resultant video coupler exhibits a high degree of linearity and stability at a low cost, while requiring minimal external circuitry to handle standard video signals.

Abstract: A signal coupler couples more than three transmitter-receivers through optical fiber cables and at least one repeater on a bit-multiplex system, by exchanging or reallocating each time slot according to a transmission station and the related destination. The coupler has a means to release the bit-multiplexing (or demultiplex) the signals from each transmitter by deriving the control clock signals from the information signals themselves. The coupler also has a means for multiplexing the bit signals for each destination by automatically adjusting the phase relationships among the released signals (demultiplexed signals) for bit-synchronization using a delay circuit.

Abstract: An optical communications system for providing wavelength division multiplexed communications with high spectral channel density and increased sensitivity and selectivity through coherent detection utilizes a fixed frequency source for introducing at least one fixed frequency carrier for system-wide propagation through a system bus. Terminal devices coupled to the system bus functioning as transmitters remove a portion of the system-wide carrier energy and effect a frequency translation and modulation of the translated carrier energy for return to the system bus as a modulated, frequency shifted information bearing signal. Terminal devices functioning as a receiver effect either synchronous homodyne or heterodyne coherent detection by removing a portion of the system-wide carrier energy, optionally effecting a frequency translation, and combining the frequency shifted carrier energy with that of the frequency shifted information bearing signal to effect coherent detection.

Abstract: This device comprises, at a first end (1) of the line, at least one controlled voltage source (SV2) and a current receiver (RI2) capable of detecting the current (I) flowing in the line (L) and, at the second end (3) of the line, at least one controlled current source (SI2) and a voltage receiver (RV2) capable of detecting the voltage (V) present on the line, the controlled current source (SI2) being adapted to impose the flowing in the line (L) of a programmable current (I) that is independent of the voltage receiver (RV2), of the voltage source SV2) and of the current receiver (RI2), while the controlled voltage source (SV2) is adapted to impose on the line (L) a programmable voltage (V) that is independent of the current source (SI2), of the current receiver (RI2) and of the voltage receiver (RV2).Application to electronic ignition systems for internal combustion engines.

Abstract: An optical switching system is disclosed comprising a set of optical hardware operating on control status supplied from electronic or electromechanical devices connected in a communication network to connect subscribing devices in the network for data transfer, wherein both control information for the system and the actual data information to be passed between two connected devices are coded in position coded light spots, and carried to the switching system by optical fibers.

Abstract: A method for the additional transmission of information items via a digital auxiliary channel in an optical wave guide system for digital signal transmission, in which system electric signals, which are coded in a pseudo-ternary bipolar code, are converted into a redundant, binary line code and are transmitted in converted form via an optical wave guide. In each case one information unit of the information items is transmitted by modification of a selected bit pattern from the data stream present in line code. According to the method, the pseudo-ternary bipolar code is the HDB-3 code, the MCMI code is used as the line code, the bit sequences 110011 and 001100 are used as selected bit patterns and at least one of the bit sequences 011011, 100111 and 101101 is allocated as a modification to the bit sequence 110011, and at least one of the bit sequences 001001, 000110 and 010010 is allocated as a modification to the bit sequence 001100.

Abstract: An optical network (46) for providing a wideband, true time delay phased antenna array (100) with simultaneous multiple beam capability is disclosed. The network (46) is provided for connection between plural beam ports (48-52M) and plural antenna elements (20-24N) for converting a received radio frequency (RF) planar wavefront (10) to plural in-phase signals at one and only one beam port (48-52M) for each respective one of a plurality of directions of wave propagation. The converse is true for a transmitted wave. The network (46) includes a laser (30-34N) for each antenna element (20-24N) or each beam port (48-52N) modulated by RF energy which is separated and delayed via optical dividers (35-39N) connected to optical combiners (40-44M) by optical fibers (46) of different lengths. Substantially all signals then arrive in-phase at one particular beam port (48-52M) for a receiver (56-60M) receiving a wave at one particular corresponding angle.

Abstract: A switch node for the communication of circuit switched and packet information via parallel electrical and photonic connections within the node between input links and output links. The links each have electrical and optical sublinks. A node is responsive to an address received via the electrical sublink of an input link to establish both an electrical and photonic connection for the subsequent communication of both electrical and photonic data to an output link designated by the address. The switch node selects the designated output link from a set of similarly address designated output links all of which are equally capable of establishing the path. Based on this type of selection within the node, a switching network with a plurality of stages using the nodes has multipaths between any given input port to any output port.

Abstract: An optical fiber communications system includes a closed loop birefringent optical fiber bus for supporting optical energy propagated in a first and a second orthogonal polarization state. An optical energy source introduces a fixed frequency system wide carrier onto the optical fiber bus in a first polarization state for propagation in a first direction. Terminal devices coupled to the optical fiber bus include a bus tap resonator for removing a portion of the system wide carrier light and, in addition to modulating the removed light, effecting a frequency shift to a side frequency and effecting a state shift from the first to the other polarization state, and returning the information bearing optical energy to the optical fiber bus for propagation in a direction opposite to the first direction. A receiving device includes a bus tap resonator for removing a portion of the light from the bus and effecting demodulation to recover the information bearing signal.

Abstract: An optical multiplexer-demultiplexer comprises a one-piece support having three grooves arranged according to a T pattern to accommodate the stretched ends of three optical fibers to be coupled. A slit is arranged at an angle of substantially 45.degree. to the grooves and at the apex of the T pattern and contains a dichroic plate. The plate is made of a substrate carrying dichroic layers. The fibers are held in the groove by an index matching adhesive. The various members of the multiplexer-demultiplexer are assembled at the work site.

Abstract: An optical signal receiver for operating over a very wide frequency passband having 3dB points at a few kHz and at 1 GHz or beyond, comprises an input stage (Q1, Q2), an amplifier (Q3 to Q6), an output stage (Q7), and a negative feedback resistance (R26) of one to several kilohms. In order to obtain high amplifier gain, the load resistance (R8) of the input stage is increased to the point where it sets up, together with the input capacitance, a lowpass filter pole within the receiver passband, said pole being compensated immediately thereafter by a link (10, C6) between the first and second stages (Q3 and Q4) of said amplifier.

Abstract: A coherent lightwave demodulator is disclosed which is insensitive to the polarization state of the incoming message signal. The demodulator includes a pair of optical hybrids (aligned to the polarization state of the local oscillator) and a pair of optical balanced receivers. A squaring arrangement, for example a delay demodulator, responsive to the output from the pair of optical balanced receivers eliminates the polarization-dependent component of the message signal and allows the recovery of the message signal regardless of the polarization state of the incoming message signal.