Abstract: These improvements to semiconductor lasers allow the fabrication of high-efficiency photoemitting devices thanks to a decrease in the threshold current necessary to optical emission stimulation. They consist in the application of a suitable magnetic field apt to confine carrier current within a limited zone of the active layer.

Abstract: This structure for a dichroic antenna can be used in a reflector antenna capable of operating at the same time at two different frequencies or with two orthogonal polarizations, and presents mechanical characteristics allowing its use on board the satellites. The structure, suitable for a subreflector, comprises a plurality of layers with high mechanical stiffness in the external part, followed by layers with low dielectric constant and one or a plurality of metallic grids in the most internal part, separated by low-dielectric constant layers.

Abstract: The local network comprises a plurality of active nodes (N1 . . . Nn) placed along a folded unidirectional bus (1) which presents a writing branch (1W) and a reading branch (1R). The nodes present means (RR) for network reconfiguration in the presence of a failure, through an isolation of the parts concerned by the failure, through an isolation of the parts concerned by the failure, and for regular service restoration after the repair, and means (GA) for the implementation of an ordered access protocol, which is based on the physical position of the nodes (N1 . . . Nn) and allows hybrid frames to be transmitted through the bus (FIG. 1).

Abstract: The monochromator presents, in the plane of the slit (5), a mirror (6) which reflects the radiations comprised within the spectrum portion selected by the slit (5) towards the grating (3) dispersing a non-monochromatic beam. The radiations reflected recombine into a single, substantially monochromatic beam on the grating (3), and a suitable optical system (7,8) focuses such a beam forming the substantially monochromatic image of the source (1).

Abstract: A network for supplying identical biasing voltages and programmable direct currents to a plurality of mutually similar transceivers, connected across respective transmission lines, is integrated with the associated transceivers in a common semiconductor body and comprises a generator of fixed reference voltage determined by the band gap of the semiconductor. The reference voltage is applied in parallel to the bases of several NPN transistors emitting the same biasing voltage as a result thereof. This reference voltage also drives an NPN pilot transistor lying in series with an external resistor through which it draws a small programmed current. Through two cascaded amplification stages formed by NPN transistors operating in the ECL mode, with the second stage designed as a multiple-output current mirror, the programmed current is stepped up to provide the several direct currents required by the associated transceivers.

Abstract: The device consists of a transparent container, partly filled with a ferromagnetic fluid surrounding a bubble of a transparent liquid. By an external magnetic field the ferromagnetic fluid is displaced within the container and moves the bubble making it pass between a light source and a light sensitive element.

Abstract: The circuit comprises two registers (SR12, SR8) which temporarily memorize uncompressed and compressed PCM words, respectively. The uncompressed word is sequentially read and a counter (CNT) counts the number of zeroes present in the most significant positions of the absolute value of the word. The compressed word is composed, in the corresponding register, of the sign bit of the uncompressed word, followed by the counting bits of the counter and by the bits of the positions of the uncompressed word following those of the counted zeroes.

Abstract: The system comprises a plurality of units arranged along a unidirectional line whereupon information is transmitted relevant to circuit switched and packet switched communications and organized into hybrid frames comprising a region for each communication type. The units comprise devices handling the access to the line which cooperate with one another and with a frame signal generator, centralized or associated with each unit, to implement in distributed way an ordered protocol without collisions in both frame region, based on physical unit location.

Abstract: A method and an apparatus wherein a light beam is passed through a slit oscillating with respect to the beam, and a periodic signal is obtained from the beam portion traversing the slit. The periodic signal is split into its spectral components. Moment values are derived from the values of the amplitudes of such components.

Abstract: Airtight rotating joint, composed of a fixed part and of a rotating one both equipped with an axial conduit ending in a chamber, rendered airtight and separated from the outside by means of a second pressurizable chamber. The joint is particularly suited to equipment where high-purity materials are to be handled.

Abstract: The method uses a raw-material and dopant-deposition technique, which requires vapor-state reactants and thermal sources for producing a temperature gradient suited to obtain a circularly and radially varying refractive-index profile in the supporting tube.

Abstract: The cut-off wavelength of the first higher order mode in optical fibers for telecommunication is measured based on the fact that the introduction of perturbations in an optical fiber can generate greater losses on higher order modes than on the lower order modes. A spectral scanning of the fiber output power is effected under a certain number of different perturbations conditions and the values obtained are combined so as to determine the fraction of power guided in the fundamental mode. The cut-off wavelength is that where this fraction exceeds a certain value.

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: A variable-band distributed switching node comprises a plurality of independent modules (MU.sub.1 . . . MGm) inserted between subscriber or trunk lines and a common bus (1). Each module includes an input/output portion (IU, HL, SL, PL), processing line information, and an interface (IB) toward the bus which co-operates with the interfaces of the other modules to form hybrid frames on the bus. These frames are each divided into a first region RC, encompassing a plurality of channels assigned to circuit-switched communications, and a residual-band second portion RP shared by packet-switched communications. Such frames are dynamically managed by assigning to each circuit-switched channel a band which can differ in consecutive frames to satisfy the requirements of variable-band sources and by recompacting the channels remaining in region RC after each channel release.

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.