Abstract: Rather than synchronizing clocks between two stations in an optical communication system by correlating a received synchronization signal with an own-station synchronization signal and controlling the own-station clock accordingly, the correlation takes place in one station (EX), but the correlation product is evaluated in the other station (E1-E3), and the clock signal of the latter is controlled accordingly. This may be done by sending a first synchronization bit sequence from a terminal (E1-E3) and looping it back in an exchange (EX) at the bit rate of a second synchronization bit sequence, wherein the clock generator of the terminal (E1-E3) is controlled according to the received correlation bit sequence. This has the advantage at the exchange that synchronization requires only optical switches and no optical-to-electrical transducers. It permits all optical exchanges and eliminates one optical-to-electrical transducer per connected subscriber.

Abstract: A converter device that transforms an input voltage (VE) into several output voltages (V1, . . . ,VN) includes a transformer (T), a first switching control device (PWM) that generates a first switching control signal (Q1) to control the switching of a first switching element (M1) and thereby regulate a main output of the converter, and a second switching control device (SDCC) that generates a second switching control signal (Q2) which is a function of both the first switching control signal (Q1) and of a second output voltage (V2). This second switching control signal (Q2) controls the switching of a second switching device (SDC) in order to regulate a second output voltage of the converter device.

Abstract: A laser source supplies a primary laser beam. A phase grating generates two secondary beams from the primary beam so as to form interference fringes that are inscribed in an optical fiber by photo-refraction. An optical system of variable focal length varies the gap between the interference fringes so as to vary the pitch of the Bragg grating discretely for successive segments of the optical fiber. Means displace the primary laser beam and the optical fiber relative to each other by successive segments of said fiber. These means are synchronized with the variation of the focal length of the optical system. Application to telecommunications.

Abstract: Selection switches (C1, . . . , C3-4) enable an optical path (BC, C1, C2-1, C3-1, D1, B1) to be selected from a plurality of such paths predefined on a common substrate (PE), each of the switches belonging to a plurality of such paths for that purpose. Isolation switches (D1, . . . , DN) each belong to one such path only. The isolation switches are disposed at the ends of the paths so as to enable the selected path to be isolated from optical members (LEN) that are outside the selector and that are connected to the non-selected paths. In this way crosstalk is avoided. The invention applies in particular to backing up an optical link.

Abstract: A semiconductor substrate includes an active waveguide to guide optical signals to be amplified occupying signal channels within a gain band of the waveguide. A stabilizer system comprises two Bragg reflectors tuned to a resonant wavelength in the gain band but outside the signal channels. It includes a gain segment in a resonant cavity. Two rejector Bragg reflectors sandwiching the resonant cavity between them are tuned to the resonant wavelength. Applications include telecommunication systems.

Abstract: A method for producing a cascaded optical space switch and a cascaded optical space switch manufactured with this method are shown being made of many optical branches produced on a single substrate. Here a method is used for growing active, i.e., controllable light amplifying or light absorbing waveguide areas, which can produce locally restrictable different layer thicknesses and/or material compositions of the grown active layers, during the same operation. The number and location of active (1, 3) and passive (2, 4) waveguide areas can be determined by the configuration of areas (M), e.g., masked with SiO.sub.2, prior to the actual growth.

Abstract: An integrated opto-electronic component includes an amplifying segment coupled to a tuning segment to provide a wavelength tunable laser oscillator function insensitive to the polarization of optical waves that it receives. The amplifying segment is designed to be insensitive to polarization. The tuning segment includes a Bragg grating and a waveguide dimensioned to procure transversely monomode laser emission with rectilinear polarization. Applications include wavelength converters and stabilized gain amplifiers, in particular for optical transmission.

Abstract: An acoustic-optical device for optical filtering includes two successive acoustic-optical interaction segments separated by an intermediate polarizer and each modifying the polarization of light guided by it. The modification depends on the frequencies of the interacting optical and acoustic waves. The acoustic waves are supplied symmetrically to the two interaction segments from a common electro-optical transducer. The transmission spectrum of the optical filter is subject to apodization by coupling between an auxiliary acoustic waveguide including the transducer and a main acoustic waveguide including the optical waveguide. Applications of the device include fiber optic telecommunication systems.

Abstract: A low-cost implementation of a voice message system is indicated. To that end, a digital signal processor (DSP) and a second memory (ROM) with program modules for executing the functions of "automatic operator" and/or "mailbox" are integrated in a digital telephone (TE4). In addition, the digital telephone (TE4) is able to execute an "individual messages" function, whereby a message intended only for another telephone (TEA) is transmitted to this other telephone (TEA) by means of the digital telephone (TE4).

Abstract: A method and a facility for communication between packet mode supporting units interconnected in the core of a communications installation by point-to-point links that are physically structured and time governed in identical manner, a packet being transmitted between two packet mode support units of the installation after the unit desiring to transmit has previously sent a request to the destination unit and the destination unit has responded with a corresponding acknowledgment. The communications facility constitutes a distributed type asynchronous switch in which each packet mode support unit includes a packet communication circuit to which the point-to-point links terminating at the unit are connected via a switching module. The communication circuit conditions each of the packets that is to be transmitted to another packet mode supporting unit of the installation in the form of a sequence of cells, and also performs inverse conditioning.

Abstract: To prevent competitive situations when accessing a bus, it is known to use control circuits and to coordinate the access of the information sources to the bus by means of organization lines between the information sources and the information sinks. According to the invention, the access entitlement is switched from one information source to another by the desire to access, which is triggered by the information offer via a control line (TSDIS) connected to the information source (MAC-ASIC 1, MAC-ASIC 2, MAC-ASIC 3, MAC-ASIC n). The method can be used in a telecommunications installation operating according to the DECT standard or the CT 2 or CT 3 standard, if, when the subscriber changes location, the original radio connection is changed from a first base station (BS 1) to a second base station (BS 2), which has a better transmission path available.

Abstract: To produce a telecommunications system and terminal equipment, which brings about immediate action for important incoming calls. User information in an incoming call is evaluated according to predetermined criteria, and a message is sent to the recipient at his current location. The data received as a result of an incoming call are evaluated by a data processing installation or a telecommunications terminal, and a message is dispatched. The message reaches the called party, who is able to retrieve and view all of the data on another communications installation.

Abstract: A portion of the surface of the first structure is protected by an oxide deposit, and the non-protective layers are etched down to a stop layer. The layers in the etched zone are then built up by molecular beam epitaxy, and one of the built-up layers is given a composition that is different from the composition of the corresponding adjacent layer in the first structure. The method is applicable to fabricating an integrated semiconductor comprising both a laser and a modulator.

Abstract: A method of estimating the pitch of a speech acoustic signal in a time interval in which said signal is a voiced one, wherein the pitch corresponds to the distance between the contact points of a circle and a plot, normalized to a limit value, of the energy of said speech acoustic signal as a function of time; said contact points being obtained by rolling said circle on said plot.

Abstract: A telecommunications terminal is to be provided which is easy to operate. According to the invention, a large-area touch-sensitive input-output unit with handwriting and graphics recognition is incorporated into the terminal, so that the functions of the terminal are activated or deactivated by inputting predetermined graphic elements (so-called gestures).

Abstract: A mechanism for filtering production rules which express conditions to be satisfied, identifies during successive inference cycles rules whose conditions are satisfied for deduced facts. The mechanism includes a sorting system for ordering the conditions of the rules according to a sorting criterion in order to verify the conditions of the rules on the basis of an order in which the conditions are to be applied. The sorting mechanism activates the system for sorting the conditions of the rules only if the number of facts satisfying a rule condition is multiplied or divided by a variable factor between the current inference cycle and the last preceding inference cycle during which the sorting system was activated for that rule.

Abstract: A differential mixer (DM) used in a telecommunication radio transmitter able to operate with a 3 Volt supply includes a silicon bipolar cross-connected pair of differential amplifiers (A; B) for receiving a first input voltage (LO) at a high frequency, a pair of current sources (I1; I2), and a voltage-to-current MOS converter (VIC) for receiving a second input voltage (VIN) at a lower frequency. The converter is adapted to convert the low frequency voltage to a differential current (INN) and is coupled to the junction points of the amplifiers and the current sources. The converter further includes a regulated differential cascode circuit (P1; P2) to which the low frequency input voltage (VIN) is applied via resistors (RI1; RI2) and which is coupled to the supply terminals (VCC; GND) of the mixer via two pairs of constant current sources (PB1, PB2; NB1, NB2) respectively.

Abstract: An amplifying fiber is connected at both ends to two respective pump-forming semiconductor lasers. The connections are made via two pump injection fibers and two multiplexers. According to the invention, each of the two pump injection fibers includes a respective photorefractive filter constituting a portion of the resonant cavity of the associated pump, and serving to separate the spectrum bands of the pumps. The invention is particularly applicable to optical fiber telecommunications networks.

Abstract: A feeding method and device, particularly for a Doppler VOR system, and to a Doppler VOR system using such a feeding device. The feeding method performs a blending function, which is an approximation of the sinX/X function limitedly to the three central lobes, and is obtained by amplitude overmodulation of a single signal according to a periodic function. The blending function can be controlled through the control of the periodic function.

Abstract: A method is described for detecting erasures in a stream of sets of digital signal values received at a receiver side after transmission from a transmission side. Subsets of these sets are modulated on distinct carrier signals, each transmitted and received thus modulated carrier signal corresponding to one of a number of predetermined subset related points and to a receipt point on a carrier dependent modulation representing map respectively. The method includes the steps of:selecting for each receipt point the nearest of the predetermined subset related points;calculating a distance between the receipt point and the nearest subset related point and multiplying this distance with a map dependent weight factor;summing the thus obtained weighted distances for all subsets of a set; andmarking the latter set as an erasure when the thus obtained result exceeds a predetermined threshold.