Abstract: A differential encoder for speech encoding, typically in a 16 kHz wide band, has a self adaptive predictive filter, comprising a comparator receiving, on an additive input, successive samples of a signal to be encoded and, on a subtractive input, an estimated signal delivered by a prediction loop which receives the error signal from the output of the comparator, the prediction loop comprising a self-adaptive predictive filter, a gain control circuit and a multiplier which receives the outputs of the predictive filter and of the gain control circuit and whose output is connected to the subtractive input.

Abstract: A first switching network embodying the invention is a subscriber installation having a chain structure. In the network, the switching is distributed over a plurality of switches each connecting a terminal to the network. A second embodiment is a business network having a star-chain structure and comprising a plurality of sub-networks of chain type. The sub-networks are star connected to central switches which operate in a load sharing mode. According to the method embodying the invention, the terminals connected to the network assume themselves the responsibility for determining communication routes through the network. During a communication set-up phase, caller and callee terminals transmit call packets which are disseminated to all terminals in order to measure two so-called "distances" respectively between the caller and the callee and between the callee and the caller. These distances are after included in data packets for routing said packets.

Abstract: Process for locally increasing the refractive indexes of an electrooptical material usable in guided optics and material obtained by this process.The process according to the invention consists of carrying out an implantation of ions (6) of sulphur or a metallic dopant able to take the place of a cation of the crystal lattice of the ferroelectric material (2), followed by annealing at between 300.degree. and 600.degree. C. in order to rearrange the crystal lattice disturbed during implantation and for activating the implanted ions. Ion implantation is carried out in an inclined direction (60) with respect to the normal to the surface of the monocrystalline material (2). For a LiNbO.sub.3 monocrystal, use is made of Ti ions as the dopant. This process makes it possible to produce a guide layer (4) having ordinary and extraordinary refractive indices above those of the pure monocrystal.

Abstract: With interlaced field scanned TV, a point (P) in a field at time (t+1) is determined on the basis of points situated in said field on the same vertical (C and D), and from points situated in the fields which are adjacent in time (t and t+2). The invention provides for multi-gradient motion detection, i.e. relating not only to the points on the same vertical (C and D), and to the points (A and B) having the same position as the point (P) but in the adjacent fields, but also on the basis of points (E, F, G, and H) which are vertically adjacent to the points (A and B) in the adjacent fields and occupying the same fields. Pairs of such points on either side of the point (P) can thus be defined. Interpolation is performed along each of the available pairs, and the interpolations are weighted as a function of the corresponding gradient.

Abstract: The coding and decoding devices embodying the invention are connected by two paths, a main path and an auxiliary path, of a variable rate digital transmission network. When the main path is capable of dispatching the totality of the information rate that the coding device is able to issue, only a main coder and a main decoder, respectively of the coding and decoding devices, are active. When the main path is not capable of dispatching the totality of the picture information, an auxiliary coder and an auxiliary decoder, respectively of the coding and decoding devices, are also active and the auxiliary path dispatches the part of the information rate that cannot be dispatched by the main path. A decoder and a subtracter are provided in the coding device so as to estimate the part of information not transmitted by the main path.

Abstract: The circuit embodying the invention comprises a pointer memory memorizing J=16 decremented write pointers associated with J=16 buffer queues. A channelling word supplied conjointly to incoming data and indicating the buffer queue in which this data is to be written, addresses the corresponding decremented write pointer. The write pointer and the channelling word form a write address for a buffer memory used as a medium for the J=16 queues. A comparator detects equality between the write pointer and the read pointer and in this case inhibits the acceptance of the incoming data which would overlay data not yet read. Logic means associated with the comparator control the updating, by possible incrementation, of the write pointer values contained in the pointer memory, after each data read in the buffer queues. This circuit is particularly well suited for use in an asynchronous self-channelling packet time-division switching system.

Abstract: A device for real time computing of a sum of terms having the form .SIGMAiT).qe((n-i)T) is suitable for use in an echo canceller for a data transmission system using code 2B 1Q. The device first transforms each of the successive estimated values of qe into transformed values qde which are powers of two, by adding or subtracting 1. The successive elementary products each obtained by a shift of h by an amount selected in response to the respective value of qde. The elementary products are summed in a register.

Abstract: A double heterostructure stack comprising confinement layers (CC) enclosing active layers (CA) is formed on a substrate (S), e.g. a N+ type gallium arsenide substrate. Selective etching is performed so as to lay bare the confinement layers at different depths, e.g. CC4, CC3, CC2. The confinement layers initially receive contact layers (CP) made of P-type gallium arsenide. Regions R1, R2, and R3 are formed through the contact layers to constitute junctions with the uppermost active layers (respectively CA1, CA2, CA3). Valleys (V10, V21, V32) are formed to isolate the above-defined elementary stacks. After a metal contact layer has been formed, and after the end surfaces have been optically prepared, a multi-wavelength laser device is obtained.

Abstract: The radiating portion of the antenna is formed from two similar radiating doublets (1,3; 2,4) which are located in a single plane and are orthogonal, with the slots between driven elements of the doublets crossing one another at the center (C) of the unit antenna.The two doublet modules (1,3; 2,4) are associated with the central conductors of three-plate lines which are orthogonal, with their extensions crossing one another beneath the center (C) of the antenna. Each three-plate line consists of the plates (1,3; 2,4) of a doublet, on the one hand, a reflector, on the other hand, and between the plates and the reflector, the central conductor. The reflector is common to the two doublets.

Abstract: A circuit for performing binary calculation, the circuit being of the type having at least one cell possessing: a first bit input (Ai), a second bit input (Bi), a carry-in input (Ri-1), circuitry (1600) for generating a two input bit exclusive-OR signal (Ai.sym.Bi) and its complement (Ai.sym.Bi), circuitry (1800) for producing a result signal, and circuitry (1900) for producing a carry-out signal (Ri), the circuitry being constituted by multiplexed logic. The complemented two input bit exclusive-OR signal (Ai.sym.Bi) is produced by inverting the two input bit exclusive-OR signal (Ai.sym.Bi), thereby making it possible to utilize only 15 transistors in the most cut-down version of the circuit. The invention also relates to a circuit (20) having an addition cell (22) calculating the sum of the input bits and a subtraction cell (24) calculating the difference of the input bits. The circuitry (1600) for producing the two input bit exclusive-OR signal (Ai.sym.Bi) and its complement (Ai.sym.

Abstract: This filter circuit comprises at least one basic cell (2) arranged as a switched capacitor sampling filter, together with a clock suitable for defining two different states for controlling sampling. According to the main characteristic of the invention, the circuit includes upstream switching means (4) suitable for inverting the polarity of the signal input to the cell during one of the two states, and downstream switching means (6) suitable for inverting the output signal from the cell (2). This makes it possible to transpose the filtering frequency band of the cell (2). The circuit is applicable to manufacturing switched capacitor sampling filters in the form of integrated circuits.

Abstract: An antenna array with circular symmetry made up of an array of cylindrica shaped printed circuit elementary antennas. It is made up of small radiating sources which are placed in superposed circles on a cylindrical surface. The sources are distributed at constant angular intervals on the circles. They have little coupling between themselves. On each circle of sources, they are energized in phase and with the same amplitude. An angular phase shift can be provided between the group of sources on a circle and those of another circle. The antenna can be energized by a three-layer printed circuit line. It can be made up by an array of doublets folded into sheets. Inside the cylinder the transmitter is installed to which is applied a signal to be transmitted and which supplies the modulated carrier to the array of radiating sources.

Abstract: The packet flow of each virtual circuit is measured and compared to an allocated average value. At each transmission authorization request (DAE'), when found to be less than the average value, a positive difference brings about an authorization to transmit and is translated into a right to transmit which is proportional to the time span since the previous request, the right to transmit being accumulated. When it is found to be greater than the average value, a negative difference brings about, if the number of accumulated transmission rights is positive, on one hand, the authorization to transmit and, on the other hand, a decrementing of the accumulated number, and if the accumulated number is nil, a refusal of authorization to transmit.Some examples of systems carrying out the process are described.The process and systems are applicable in particular to packets carried by asynchronous time multiplexers.

Abstract: A switching system for switching synchronous and/or synchronous data blocks between incoming and outgoing multiplexes. The asynchronous blocks are sporadically carried in the multiplexes. The cost of the system is reduced owing to the use of a single buffer memory whose cells memorize indifferently synchronous and asynchronous blocks. The number of cells is lower than the product of the number of incoming or outgoing multiplexes and the number of blocks per frame in the multiplexes. A buffer memory managing and write addressing circuit derives and memorizes the occupied or free condition of each of the buffer memory cells thereby permanently selecting the address of one of free buffer cells in which a data block is to be written. The occupied condition of a cell is signalled responsive to the write of an incoming data block into this cell, and the free condition of the cell is signalled responsive to the last read of the written block.

Abstract: An electroluminescent display device uses a photoconductive material which is of hydrogenrated and carbonated amorphous silicon of formula a-Si.sub.x C.sub.1-x ; with 1-x preferably between 0.05 and 0.50 and which has application to display functions.

Abstract: With interlaced field scanned TV, a point (P) in a field at time (t+1) is determined on the basis of points situated in said field on the same vertical (C and D), and from points situated in the fields which are adjacent in time (t and t+2). The invention provides for multi-gradient motion detection, i.e. relating not only to the points on the same vertical (C and D), and to the points (A and B) having the same position as the point (P) but in the adjacent fields, but also on the basis of points (E, F, G, and H) which are vertically adjacent to the points (A and B) in the adjacent fields and occupying the same fields. Pairs of such points on either side of the point (P) can thus be defined. Interpolation is performed along each of the available pairs, and the interpolations are weighted as a function of the corresponding gradient.

Abstract: A system for switching information packets assigned with two levels of semantic priority between entering time multiplex lines and outgoing time multiplex lines, a storage address of a packet in a buffer memory of the system being stored in a queueing file associated with each outgoing time multiplex line designated to transmit the packet, comprising a field point (state) memory whose words each are comprised of as many bits as there are outgoing time multiplex lines, the addresses of the the field point memory corresponding to those of the buffer memory, each bit of the words being at "1" when the packets stored at the same address as the words and designated for an outgoing time multiplex line corresponds to a high level semantic priority bit and has not yet been transmitted by the outgoing multiplex line concerned, each packet storage address being chosen from the addresses of the field point memory addressing all bits of which are at "0".

Abstract: A resonant loop current disturbing probe. This probe comprises a conductive loop closed on a photoresistor, a light-emitting diode optically coupled to the photoresistor by an optical fiber and a diode control circuit. This probe is characterized in that it also comprises a variable capacitor connected in parallel to the loop. The loop-capacitor assembly forms a resonant circuit, the capacitor being adjusted in such a way that said circuit resonates at the frequency of the current to be disturbed. Application is to the measurement of the current in antennas.

Abstract: The biquad block or cell comprises two operational amplifiers OA1, OA2, eight capacitors C1-C8 and switches comprises switches of reference o and switches of reference e controlled by a clock signal H. The biquad block has six connections P1-P6 and can be used as low-pass, band-pass or high-pass filters, as a function of the connections chosen for the input and output of the signal to be filtered. Switches 46 to 52 make it possible to select one from among several configurations for each filtering function. The different configurations are distinguished by their sensitivities to the gain of the operational amplifiers and to the capacitance ratio. Application to the filtering of signals in the video range (a few megahertz).

Abstract: An optical fiber cable transmission apparatus includes repeater-interchanger modules each of which includes at least one interchange module or pair of drop and insert switches. The module is such that a drop switch and an insert switch are provided between a line input and a line output with the second input of the insert switch coming from a buffer memory. Both switches are controlled by a common synchronizing circuit. A symmetrical arrangement is provided for the other drop and insert switch. Transmission takes place at a high data rate, and the interchange module serves to extract low data rate segments from each frame relating to a first stream and to replace them with same data rate frame segments relating to another stream. This arrangement makes it possible to distribute an "underwater multiplexing" function, i.e. to reconfigure traffic over a plurality of such repeater-interchangers.