Abstract: Voltage reference is generated by a current generator which, through a current-mirror amplifier, biases an enhancement MOS transistor as well as a depletion one, so that the desired voltage is equal to the difference between their threshold voltages.

Abstract: An integrated microwave oscillator as which the generated frequency is stabilized by a dielectric resonator with high quality factor and stability. The positive feedback is assured not only by the dielectric resonator coupled to a line connected to a terminal of the active device, but also by a microstrip resonator connected in parallel to a second line connected to a second terminal of the active device. The signal generated is extracted from the third terminal of the active device.

Abstract: An interface facilitating data transmission between a control processor, connected to an asynchronous two-way bus, and a plurality of terminals, connected to a common synchronous two-way bus, comprises a microprocessor responsive to periodically recurring access requests from the several terminals. The access requests are short pulses with a recurrence period greatly exceeding their duration, this period being nominally equal for all terminals and sufficient to accommodate one data transfer to or from each terminal with time remaining for execution of part of a main program performed by the control processor. Coinciding access requests from different terminals are handled according to a predetermined order of priority. The exchange of data takes place by way of a data memory and a buffer memory linked by an internal two-way bus. Data transfer between the control processor and a terminal takes place in three stages, i.e.

Abstract: The connector ensures the alignment between the two fibres ends (9, 10) thanks to the force exerted by a locally generated magnetic field (5, 6, 7, 8) on a ferromagnetic fluid placed between the side fibre surface and a small tube (1) with a diameter greater than fibre diameter.

Abstract: The process of manufacturing optical fibers of extremely low loss in the medium infrared permits the fabrication of glass preforms having as basic materials metal-fluorides obtained from vapor-phase reactants.

Abstract: A circuit arrangement for deciding concurrent requests for access to a common data bus emitted by a number n=2.sup.m of components of different ranks, specifically multiprocessor elements, comprises n mutually identical arbitration devices respectively associated with these components. The arbitration devices are interconnected in a chain by a priority bus of branched binary structure divided into m lines connected, within each device, to a logic network that is also connected to an internal m-conductor bus extending from a priority-code register. The priority bus, whose lines are normally at zero potential, is connected in any given device to the register thereof in the presence of an access request from the associated component whereupon its logic network determines whether the code on that bus equals the contents of the register; if so, the associated component is enabled by a control unit of the device to access the data bus.

Abstract: The process allows a uniform layer of glass particles, forming the preform, to be deposited on the internal wall of a supporting tube rotated around its axis. A suitable relationship is provided to determine the temperature distribution in the deposition zone. The apparatus makes use of different types of heat sources for generating inside the tube a temperature with the distribution required by the process.

Abstract: A transceiver inserted between a source of binary signals and a one-wire line, dialoguing with a similar transceiver in series with another source at the opposite end of the line, comprises two voltage sensors connected in parallel to the line at a point downstream of a terminal impedance at which the line voltage substantially equals the mean of the voltage levels simultaneously generated by the two sources. The two voltage sensors have thresholds respectively lying at a lower and an upper intermediate level between the two binary signal levels (L, H) employed and work into a common signal receiver through a multiplexer so controlled by the local source as to connect that receiver always to that detector whose low or high output signal corresponds to the binary value (L, H) of the signal then arriving from the remote source.

Abstract: A train of incoming data words, specifically digitized video samples arrayed in frames of Y lines of X pixels each which have already undergone a 2-dimensional spatial transformation, is scrambled by being divided into Z sequences (frames) whose data words are temporarily written in respective cells of Z.sup.2 storage units of a memory of dynamic-RAM Type. The Z.sup.2 storage units, each divided into Z sections, are read out in cyclic-succession--at a rate of one cell per unit--and each cell is reloaded immediately after being vacated. Reading and writing occurs for one set of Z sequences in a first addressing mode, conforming to the order of arrival of the data words in the incoming train, and for the next set in a second addressing mode involving the grouping of homologous data words of respective sequences into successive series of Z data words each.

Abstract: An equalizer with two parallel branches for precursor and postcursor correction, receiving periodically incoming binary pulse samples, generates for each sample two purged symbols f, b at the outputs of these branches along with two decided symbols f and b, all of which are transmitted to a logic network checking whether or not the two decided symbols are identical. In the event of a disparity, the network produces an estimated signal s, calculates the absolute differences d.sub.sf, d.sub.sb between signals s and f, b, supplements them with further signals d.sub.f, d.sub.b representing the contributions of postcursors and precursors from one or more preceding and following samples, and compares resulting discriminatory signals D.sub.f and D.sub.b to determine which of the two decided symbols should be emitted as an output signal of the equalizer.

Abstract: An interface interposed between a PCM data terminal and a processor comprises a bus accessor dialoguing with the processor, input and output circuitry coupled to the terminal, and intervening logic circuits and data stores designed to supply the processor in a time-division mode with preprocessed messages received or to be transmitted over a multiplicity of channels. The interface is operable according to dialogue procedures of HDLC type such as those corresponding to CCITT recommendations X25, X75 and N. 7, with switchover from one protocol to another.

Abstract: A unit cell for a prefabricated semiconductor chip, to be converted into an array of logic gates by selective metallization, comprises two complementary pairs of MOSFETs occupying respective quadrants of a rectangular substrate area, with external gate contacts disposed in respective headers extending along the minor sides of the rectangle. Each header further contains two external channel (source or drain) contacts which with the two external gate contacts form a group of four input/output contacts. Two metallic strips serving as supply buses, parallel to the minor sides, are separated from the two headers by relatively narrow substrate zones so as to define a relatively wide central region between them.

Abstract: A two-dimensional data array, such as an orthogonally scanned television image, is divided into a multiplicity of elemental blocks each containing a given number of PCM samples which are converted by linear transformation into a series of coefficients to be quantized for transmission to a remote receiver. The data blocks are processed one at a time by an iterative coder which allots a progressively increasing number of bits to a given block in successive operating stages, the bits being allocated to the several coefficients of the block according to the position of the barycenter of their signal energy assigning the block to one of K classes. An initial overall reconstruction error, computed from the coefficients of a block with no bits yet available for quantization, is updated with each bit allotment in the course of an iteration in which a selected coefficient is subjected to simultaneous coding with S quantizers differing from one another in their quantum steps.

Abstract: Television signals generated at a transmitting station are digitized and are then transformed into bit groups by a precoder reducing their information content by eliminating redundancies, as by comparing each pixel of a given frame with the homologous pixel of the immediately preceding frame and, upon detecting their equality, emitting a particular reduction code in lieu of an otherwise emitted luminance signal. A message encoder following the precoder generates outgoing data words which may comprise a luminance value accompanied by an integrity code, a changeover signal accompanied by a reduction code, a numerical value specifying the number of consecutive pixels remaining unchanged from the preceding frame, or a synchronizing code. The bits of the outgoing data words are serialized and are temporarily stored in a buffer register in order to be sent at regular intervals, via a communication channel, to a receiving station where a message decoder regroups them in their original order.

Abstract: An adaptive equalizer for high-speed binary signals, operating in baseband, comprises a transversal filter receiving digitized samples of incoming symbols and feeding them to a decision stage. The samples also go to a coefficient computer, in parallel with that filter, which includes a filter simulator, an error calculator and a processor delivering corrective coefficients to the filter. A register in the filter simulator accumulates a predetermined multiplicity of received samples (e.g. 150) which are jointly convoluted with an initial set of coefficients to yield a mean square error supplied by the error calculator to the processor; the latter, for each coefficient of the initial set, selects two collateral values which are successively substituted for that coefficient to yield two further mean square errors.

Abstract: A body transparent to laser radiation, such as an optical fiber or a preform thereof, is transluminated by a monochromatic beam of a frequency in the THz range split off from a composite laser beam with two closely spaced frequencies produced by the Zeeman effect; the width of that beam in a plane transverse to the body axis is at least equal to the diameter of that body. Another monochromatic beam at the second laser frequency bypasses the transparent body and is recombined with the first beam downstream of the transluminated body to form a field of radiation which is photoelectrically sampled at closely spaced locations in the aforementioned transverse plane to provide a multiplicity of electrtical signals in the MHz range differing in phase from a reference wave of the same frequency photoelectrically obtained from the same monochromatic beams. The phase differences, determined by a comparator, are fed to a calculator computing the refractive-index profile therefrom.

Abstract: In order to measure the amplitude of a periodic signal of known frequency which may be heavily contaminated by noise and whose phase is not known at the point of measurement, e.g. at an output end of an optical fiber, two samples are periodically taken in every cycle at instants spaced apart by a quarter-cycle. The two samples are accumulated over N cycles and the signs of the resulting algebraic sums are compared at every N.sup.th cycle to determine whether the sampling phases should be advanced or retarded within a cycle by a predetermined increment .DELTA. in order to let the first and the second sample of a pair respectively approach the peak and the zero crossing of a half-cycle of the signal wave at which point, with the noise more or less balanced out, the second sum is substantially zero while the first sum represents N times the actual signal amplitude.

Abstract: A four-wire trunk line of a telephone network, operating with frequency-division multiplexing, is coupled by a hybrid coil to a local two-wire line and is provided, at a location separated from that hybrid coil by frequency modulators and demodulators, with an echo canceler connected across its receiving and transmitting branches. In order to eliminate frequency offset resulting from the incoherent modulation and demodulation, the echo canceler coacts with the phase-roll compensator comprising a phase-locking loop driven, during an acquisition phase, from a digital pilot-tone generator temporarily connected via a digital/analog converter to the receiving branch. The loop includes an analog/digital converter in the transmitting branch receiving the echo of the pilot tone due to hybrid-coil unbalance, a 90.degree.

Abstract: In order to obtain substances that are optically transparent in the infrared range, usable in the manufacture of optical fibers or radiation emitters, a metal or metalloid chalcogenide other than an oxide is produced by a double-substitution reaction between a starting chalcogen compound--particularly a hydride such as H.sub.2 S, H.sub.2 Se or H.sub.2 Te--and a salt of the desired metal or metalloid, e.g. a chloride. The starting compound and the reactant salt preferably are vaporized at a temperature below the melting point of the resulting metal chalcogenide which thereupon precipitates in the reaction chamber.

Abstract: An SS/TDMA communication system comprises a multiplicity of ground stations, including one master station and a number of traffic stations without control function, exchanging digitized voice or other message signals via a relay station aboard a satellite. Each ground station comprises base-band equipment including a transmitting section, a receiving section and a control unit. The control unit of the master station generates outgoing timing signals and processes incoming timing signals for synchronizing the operations of its own equipment and that of the traffic stations with the operation of a switching unit of the satellite-borne relay station; this control unit also emits routing instructions for that switching unit.