Abstract: The system uses a monochromatic radiation source (1) and an acousto-optic modulator (2), which acts as a Bragg modulator and is driven by a frequency which is caused to periodically vary. The modulator emits a first beam having the same wavelength as the source and a second beam, whose wavelength and emission direction vary with the modulating frequency and which is collimated. For measuring angular displacements, the collimated beam is recombined with the first beam after traversing a plate (5) with parallel and plane faces integral for the rotation with a moving device, and a photodetector (12) generates a beat signal whose frequency depends on the angular position of the plate (5). For measuring linear displacements, the two beams are directly sent onto a detector (12) integral with the moving device.

Abstract: A fast packet switching system has an interconnection network associated with a distributed control structure composed of a plurality of processing units (UC1-1 . . . UC3-16) managing the routing at the virtual call level. At least some processing units each associated with a group of network inputs/outputs store bandwidth occupancy data relevant to the interstage links which can be reached from the inputs of the group and are included between the inputs and a central network stage where there is a maximum number of alternative paths or, respectively, bandwidth occupancy data relevant to interstage links which lead to the outputs of the group and are included between the stage and the output, the data being updated whenever a new call is routed.

Abstract: A label-switching and control interface for asynchronous fast-packet switching consisting of a set of label-switching and cell-processing units controlled by a suitable control unit. The units operate at each multiplex level in real time thanks to a microprogrammed logic requiring the control processor intervention only at the connection set-up/release. The units implement the low levels of the flow control algorithms necessary to conveniently exploit the advantages of the techniques. The label becomes indicative of a virtual circuit which is allotted only locally to the call, annulling thus the necessity of very extensive labels, while the parameters which characterize the connection which uses a particular label are stored in the unit itself.

Abstract: The coaxial-waveguide phase shifter consists of a coaxial waveguide section, comprising an external cylindrical conductor and an internal cylindrical conductor, both hollow. Between them a number of irises are provided parallel to one another. The irises can be differently shaped and can be fixed to the external or to the internal conductor. By replacing the internal cylindrical conductor with a rectangular conductor, the irises can be unnecessary.

Abstract: The value of a transverse moment of any order of the electromagnetic field associated with an optical beam (and in particular the spot-size of such a beam) is determined by two successive measurements of the optical power of the beam: one measurement is a direct measurement, the other is effected after spatially modulating the transverse distribution of the electromagnetic field by a factor proportional to the n-th power of the transverse coordinate of the beam, n being the moment order. The moment can be obtained from the ratio between the two measurements. The invention includes also the apparatus for carrying out the method.

Abstract: An electrooptic deflector composed of a plate made of a material with a refractive index which can be modified by the application of an electrical field, whereinto a collimated optical beam can be injected in direction parallel to the electrodes deposited on a plate face. Said electrodes are parallel to one another, equally-spaced and separately connected to voltage sources apt to increase the refractive index in the material passing from an electrode to the next. The emerging optical beam is deflected in the direction wherein the refractive index increases.

Abstract: A silica glass optical fiber is subjected to an external strain which causes vitreous matrix atoms to stabilize in a lower energy condition. In this way inhomogeneity domain sizes and as a consequence the attenuation due to Rayleigh scattering, depending on such inhomogeneity, are reduced.

Abstract: A method is described for decoding messages coded as blocks consisting of a fixed number of symbols and affected by symbol substitutions, deletions and insertions, wherein for each received message having a length comprised within predetermined limits, a sequence of words (error frames) is generated which comprise all possible error combinations which can be corrected in the message. By using such error frames, a decoded word is generated for each frame, the probability that a decoded word actually is the transmitted word is calculated and the decoded word, whose probability value satisfies predetermined criteria, is emitted as a decoded message. A device for carrying out the method is also provided.

Abstract: In a method for the automatic frequency control of semiconductor kasers, the signal emitted from the laser (1) is sent to an optical resonator (6) whose resonance frequency is modulated by a ramp signal, the signal outgoing from the resonator (6) is converted into an electrical signal, the derivative of such an electrical signal is calculated, the zero crossing of the derivative is detected, the ramp signal is sampled in corresponding with such a zero crossing, and the sample thus obtained is algebraically summed to a reference signal depenent on the nominal laser emission frequency, thus obtaining an error signal which is sent to devices (3) driving the laser (1). In case of a plurality of lasers (1a . . . 1n) the signals of which are wavelength multiplexed, the rame signal is sampled in correspondence with the derivative zero crossings corresponding with the emission frequencies of the individual lasers (1a . .

Abstract: A fixture for measuring the static characteristics of microwave active components has mechanical devices for supporting two dielectric substrates. Two terminals of the components under test are separately connected to electrical circuits constructed on said dielectric substrates. This fixture can be adapted to geometric sizes of component case and allows it to be submitted to thermal tests, without mechanical stresses due to expansion. The electrical circuits constructed on the dielectric substrates ensure circuit stability avoiding spurious oscillations during static characteristic measurement.

Abstract: The elementary adder, as far as carry propagation is concerned, has two circuit branches: the first is an inverter (II) followed by a transfer gate (T1, T2) activated when two operands have opposite logic levels, in which case it transfers complemented input carry Cin to the output CoutN; the second consists of a 4-transistor series cirucit, two P-MOS (T3, T4) and two N-MOS (T5, T6) geenrating carry output CoutN complemented when the two operands have equal logic levels.

Abstract: A device for coupling single-mode optical fibers, wherein light radiation outside the fibers is transmitted through a collimated optical beam, obtained by a two-lens array facing the fiber ends. Optimal coupling is obtained by translating a third lens and by rotating a small glass plate placed between the collimating lenses.

Abstract: The switching element for self-routing multistage packet-switching interconnection networks comprises: an input unit, composed of as many sections (IMA, IMB) as the element inputs are, each section comprising a FIFO memory (FIFA, FIFB) for packet buffering; a switch (SW) associated with a control unit (SCU) which, for each packet to be forwarded, sets up the connection requested for that packet between one input and one or more outputs of the element (ECP), on the ground of a routing tag associated with each packet and comprising a first and a second portion relative to normal routing and to broadcasting in the different stages of the network (RC), and solves possible routing conflicts between packets simultaneously arriving at different inputs; and an output unit, composed of as many sections (RU0, RU1) as the element outputs are and performing the whole of the functions necessary for the correct packet forwarding towards a destination.

Abstract: The arithmetic-logic unit has elementary cells performing logic addition, one for each pair of operand bits, which are particularly optimized as far as carry propogation speed is concerned and are controlled by an auxiliary fast logic allowing their performance to be extended to the other operations. The unit also has a control signal generating circuit, subdivided into a first part (DEC1), near the elementary cell of least significant position, which generates an operation selecting signal for all the cells, and into a second part (DEC2), near the elementary cell of most significant position, which generates control signals for the auxiliary logic of each elementary cell.

Abstract: A constant force perpendicular to the fiber axis is applied to the fiber so as to cause a power coupling from the fundamental mode, which is guided, to a secondary mode which is irradiated, and the intensity of the scattered radiation associated with that secondary mode is measured. Such intensity depends on the local state of polarization. By dispacing the force application point step by step along the fiber axis and by measuring for each point the intensity of the scattered radiation, beat length is obtained as the distance between two consecutive points where the scattered radiation has the same intensity.

Abstract: This method provides a filtering of blocks of digital samples of speech signal by a linear-prediction inverse filter followed by a shaping filter, whose coefficients are chosen out of a codebook of quantized filter coefficient vectors, obtaining a residual signal subdivided into vectors. Each vector is classified by an index q depending on the zero-crossing frequency and r.m.s. value; it is then normalized on the basis of the quantized r.m.s. value, and then of a vector of quantized short-term mean values; the mean-square error made in quantizing said vectors with vectors contained in a codebook and forming excitation waveforms in computed. In this codebook the search is limited to a subset of vectors determined by index q and p of short-term mean vector. The coding signal consists of the index of the filter coefficient vector, of indices q, p, of quantization index m of the r.m.s. value, and of the index of the vector of the excitation waveform which has generated minimum weighted mean-square error (FIG. 1).

Abstract: The circuit consists of two parallel branches which perform multiplication and accumulation operations for the even and odd lines of the transform coefficient matrix. Each branch includes: an input circuit (SEM1, SOT1) whereby the contributions of the opposing index columns of the matrix may be added; a multiplication circuit (ERM, ORM) which performs multiplication operations for each matrix column by an addition and shifting operation for each matrix coefficient; and an accumulation circuit for the intermediate products of each matrix column.

Abstract: An optical switching system, wherein the input channels carrying packetized data are switched one-by-one at high bit rate to output channels through an optical switching network. The packets of a generic input channel are time compressed, converted into optical signals and, at suitable instants, sent to an optical switching network to be switched to the desired output channel, they are then reconverted into electrical signals and expanded to their original duration. A centralized processor controls the channel switching through the switching network by means of a driving circuit.

Abstract: A method of accessing a local-area network which allows transmission on a unidirectional ring, of circuit-switched or packet-switched communications organized in hybrid frames, in which overlapping between the beginning of a frame and a residual of the preceding frame which is still to reach its destination is avoided without reporting to a rigid band allotment to the indiviual communications and to a network synchronization system, where a well defined node acts as a master clock. According to the method the individual nodes of the network, access in sequence the transmission line in each frame, maintaining the same order of asynchronous access in the circuit and packet regions.

Abstract: A system for automatically controlling the gain-bandwidth product of operational amplifiers, wherein a gain-bandwidth product (G*B) of one of the amplifiers placed on the same chip as the amplifiers to be controlled is measured and the resulting signal is used to control through a bias circuit, the gain-bandwidth products of all the amplifiers, the value of these products being presettable by the frequeny of a control signal sent to the system input. The reference amplifier is highly compensated in the configuration of voltage follower.