Abstract: According to the coding method, the digital speech signal is split into subbands; each subband is coded independently of the others. The first two subbands undergo an adaptive linear prediction operation yielding a residual, normalized with respect to a quantized r.m.s. value; the residual samples are quantized and coded by a variable bit number. As to the third subband the samples normalized with respect to a quantized gain term are directly quantized and coded by a variable bit number. While splitting the subband signals into sample blocks, for the first two subbands the coefficient vectors of subband linear prediction filters relevant to each block are also determined by vector quantization and linear prediction inverse filtering operations; quantized r.m.s. values are also determined to calculate the numbers of bits permitting subband signals coding. The coded signal consists of subband signal quantization level indices, of r.m.s.

Abstract: The method of and the device for digital signal coding by vector quantization exploit representation of signal portions in a one-dimensional space for vector codebook generation and for coding for transmission and/or storage purposes. The n-dimensional sampling is transformed into coordinates in one-dimensional space preferably in accordance with Hilbert's curve.

Abstract: Outgoing light signals from a virtual point source are transmitted to a confronting end of an optical fiber via a microlens, whose diameter approximately equals the fiber diameter, axially traversing a center hole of a large-diameter circular photodetector illuminated by incoming light signals from the same fiber end. A focusing lens or objective may be interposed between that fiber end and the photodetector with its microlens to create a field of parallel rays therebetween. The photodetector may be angularly subdivided into a plurality of sectoral portions which are electrically interconnected in series for producing an increased output voltage.

Abstract: A static interferometric ellipsometer, wherein a source (3) generates a coherent light-beam with two monochromatic radiations at slightly different frequencies. A first photodetector (6) generates a first beat between the two radiations, to be used as reference. A second photodetector (9) generates a second beat between the two radiations, after they have been polarized in perpendicular planes and separated so that one of them is reflected onto the photodetector (9) by the sample under test (1,2). A measuring and computing system (11) determines the optical properties of said sample starting from the intensity of the second beat and from the relative phase between the two beats.

Abstract: The digital phase-locked loop circuit extracts the clock signal from a serial flow of coded data by operating so as to determine the phase of the received signal and comparing this phase with that of a locally-generated signal. The error signal obtained from the comparison is digitally filtered and used to correct the phase of local signal. The error with respect to the signal extracted from a prior data stream is stored and used to effect corrections even in the absence of the data flow at the input or in presence of long zero sequences.

Abstract: A constant force perpendicular to the fiber axis is applied to the fiber and is displaced step by step along the fiber axis. The state of polarization of a radiation outgoing from the fiber is determined at each step and the beat-length values are obtained from both the amplitude ratio and the phase difference between the components, along the two birefringence axes, of the electrical field associated with a radiation launched into the fiber.

Abstract: The device obtains several characteristic parameters from a standard sentence said by a speaker and compares them with average parameters of the same speaker stored in an internal memory and previously calculated. According to the comparison, it obtains a probability value that the sentence spoken belongs to that speaker and compares the value with a threshold normalized to the average parameter variance by a threshold calculation circuit. If the threshold is overcome, the device considers the speaker verified. A circuit determines the real instants of sentence beginning and end using a noise-adaptive threshold in order to limit between these two instants the time interval over which characteristic parameters are to be calculated. A circuit aligns as to time the characteristic parameters just calculated to the parameters of a reference sentence, obtaining standard lengths of the sounds composing the sentence spoken.

Abstract: The method of surfacing the heater of a furnace for optical fiber drawing allows elimination of defects in the inner heater surface, which defects give rise to particle emission towards the preform. This is achieved by depositing a thin layer of a mixture of oxides compatible with the material composing the heater.

Abstract: The basic element provided by the invention carries out the basic logic functions of storage and/or transfer of the data applied at the input, typical of a latch. Two ways of embodiment of the basic element having active phase at the high and low level of the clock signal are described. The basic element presents a transfer-gate transistor at the input controlled by the clock signal, followed by an inverter at whose signal leads two positive feedback networks are connected, one of which controlled by the clock signal, to stabilize the logic levels (FIG. 1).

Abstract: The broad-band integrator uses bipolar transistors with single low-value integration capacitor, that is why it is easy to integrate. A bias circuit, which can be integrated, allows both the gain-bandwidth product (G*B) and the absolute values of the currents in the transistors to be programmed by two external resistors. A plurality of integrators, typically sixteen, can be connected to the same bias circuit thanks to their small power consumption.

Abstract: A broadband signal broadcasting system comprising a circuit to encode video and audio signals forming a TV channel to be sent to a switching matrix, which is remotely operated by the subscriber; a circuit to multiplex two or more TV channel to be simultaneously transmitted on the subscriber's line, which can be a coaxial cable, a radio link or an optical fiber; and a circuit to receive the signals transmitted on the line, to separate two or more TV channels and to carry out channel decoding by supplying the subscriber's terminals with the corresponding video and audio signals. The system requires a single encoding and a single decoding of the nB.fwdarw.(n+m)B type on broadband signals, respectively at the output from signal sources and at the input of subscriber's terminals.

Abstract: A method of and an apparatus for measuring the softening point of a vitreous specimen in which the viscosity variation as a temperature function is determined by applying torsion to the specimen and measuring the transmitted torque as a function of temperature.

Abstract: The process for manufacturing halide glasses uses a reaction between organometallic and inter-halide or halide-derived compounds, started at a temperature ranging from the highest melting temperature and the lowest boiling temperature of the compounds used.

Abstract: Speech synthesis is selectable in two modes: "normal" mode in which the synthesis filter is responsive to prestored parameters, and "test" mode which executes a checking procedure based on test words from an outside source. Each mode has corresponding instructions prestored in a memory.

Abstract: The improvements relating to capacitive devices for measuring the diameter of a dielectric fiber are based on a particular shaping of the capacitor plates, such as to allow electric field reductions at the edges to be compensated for and hence capacitance measurements to be unaffected by fibre vibrations.

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.