Abstract: A bidirectional optical wavelength multiplexing-demultiplexing device comprises a self-focusing lens having an index gradient and situated between the transmission fibre and filtering means and of which the length is such that the spatial separation between the outgoing wavelengths and the return wavelength is maximum, which permits decoupling of the return channel from the outgoing channels.

Abstract: The device for protecting optical fibers freed at the end of a cable element comprises a sleeve in which the end of the cable element is forcibly fitted, and a plurality of flexible sheaths mounted in securely fixed relation in the line of extension of the sleeve. Each optical fiber which has been freed from the cable element is positioned within and protected by a corresponding sheath.

Abstract: The invention relates to an optical wavelength multiplexer-demultiplexer using optical fibers. For a bidirectional three-channel link with two go channels and one return channel the multiplexer-demultiplexer comprises a chamfered link fiber (30) provided with an interference filter (25) and optically coupled with three intermediate fibers (13, 14, 15). A first intermediate fiber (13) is chamfered and fitted with an interference filter (20) and has an optical axis which intersects the optical axis of the link fiber at a given angle (.theta.), while a second intermediate fiber (14) is coupled to the chamfered fiber, with the filter (20) providing multiplexing and demultiplexing between the two go channels. A third intermediate fiber (15 is applied to the cylindrical wall of the link fiber to receive or tansmit the return channel via the filter (25). The multiplexer-demultiplexer is applicable to optical fiber telecommunication systems.

Abstract: A device for distributing light energy comprises a chamfered inlet fiber (2) which is coupled to a plurality of outlet fibers (3) which are grouped together in a matrix. The coupling is performed by a diffraction grating (5) which is inclined relative to the chamfered inlet fiber at such an angle that the diffracted beam is a parallel beam, and the matrix of outlet fibers is disposed on the path of said outlet beam. Such a device is applicable to optical fiber distribution systems.

Abstract: A synchronization device for digital data frame transmission system comprising an n bit series register transferring its contents at the line frequency to a parallel register also of n bits. The m first bits of the series register are also directed to a logic circuit which tests their conformity with the beginning of the synchronization word. When there is conformity, the logic circuit controls a divider dividing by n which controls, in its turn, at the line frequency divided by n, the transfer of the contents of the parallel register to a PROM memory. The purpose of the PROM is to recognize the entire synchronization word. When there is no recognition, the operation of the divide by n divider is inhibited and the procedure begins again.

Abstract: A process for time-sequenced multiplexing of telephone data, PCM coded, on a transmission medium, and more specifically a process for multiplexing three 10-channel systems to form a standard 30-channel system, wherein:frames and multiframes are identical in structure for all 10-channel systems;each 10-channel frame contains 11 time intervals of the same length, the first of which contains auxiliary data, for synchronization, channel signalling, etc., and the last ten carrying information to be transmitted, coded by the pulse modulation and coding technique;each multiframe comprises the same number of frames as the 30-channel system;signalling and synchronization data is distributed among the first time intervals in the different frames, such distribution ensuring reliable synchronization and minimum delay, during the change from 10 to 30 channels and vice versa.

Abstract: The receiver of an optical-fiber transmission system comprises a device for restoring each digital signal comprising a first comparator comparing the level of the electric signal with a first reference level and generating a signal when the level of the electric signal is less than the reference level, a second comparator comparing the level of the electric signal with a second reference level and generating a signal when the level of the electric signal is greater than the reference level, and a summator summing the signals generated by the two comparators.

Abstract: A process and system are provided for transmitting additional information, called order track, superimposed on the information to be transmitted, by alteration of the coding law. The process involves:detection of at least one possible value of the information to be transmitted, for which the coding law is altered depending on the order track information.The first coding is transformed into a second coding by choice of one of several alphabets capable of ensuring such a transformation, this choice being effected depending on the value of the current numerical sum, in accordance with the coding law such that the value of this numerical sum is minimized.the output at one end of the transmission channel of the information is expressed in the second coding as altered by the order track.The information received at the other end of the transmission channel is transformed into information expressed in the first coding.The order track is detected by detection of the alteration in the coding law.

Abstract: A process is provided for synchronizing at reception digital signals transmitted in packages which consists in generating the signals of a first window of given width at intervals corresponding to the timing of the on-line packages, in searching by detection for at least one transition in the signals received during the duration of each window, in modifying the interval between the beginning of a window signal and the beginning of the following signal in the case where the transitions detected do not correspond to a given criterion and in maintaining said interval equal to said on-line package timing and producing a synchronization signal fed to a package reading device in the opposite case. The device of the invention comprises a dividing counter which is reset by the transitions detected in the window so that the interval between the successive windows is modified until the synchronization is acquired, that is to say that the end of the window is located at the level of the synchronization transition T.sub.

Abstract: The device for supporting a cutting-tool is intended to be placed in a head for machining grooves in a cylindrical rod and mainly comprises a frusto-conical support member having an axial bore through which the cylindrical rod to be machined is capable of passing. The support member is placed within a frusto-conical recess of the machining head and provided with a cutting-tool recess having an opening which defines the profile of the cylindrical rod. The cutting-tool is clamped within its recess by means of a ring which is screwed into the support member and has a control front face for receiving the rod to be machined.

Abstract: A device is provided for positioning optical fibers in a terminal connector for splicing two optical-fiber transmission cables, said device comprising an optical-fiber insertion piece having a central recess in which is fitted a terminal connector provided with grooves, and radial slits provided on the periphery of said insertion piece, and optical-fiber distribution means mounted freely rotatable on said insertion piece and having a longitudinal slit intended to come successively opposite each slit of said insertion piece, so that, by rotation of said distribution means, each optical fiber penetrates into a groove of said terminal connector through the slit of said distribution means positioned opposite a slit of said insertion piece.

Abstract: A device for separating two light signals having different wavelengths transmitted in one and the same optical fiber, comprising an optical fiber terminating in two branched-off portions of fiber having in one case an extension of predetermined length, two photodetectors placed respectively at the output of said extension and of the other branched-off portion of fiber, delay means connected to the output of one of the photodetectors, differentiating means for receiving the signals generated by the delay means and the signals detected by the other photodetector, and an electronic processing circuit connected to the output of the differentiator.

Abstract: A sampler is constituted by a section of a rectangular waveguide in which are mounted two diodes connected in series by means of a conductor which is placed at equal distance from the two large faces of the waveguide, one end of the conductor being connected to the input of the sampler and the other end being connected to a matched load.

Abstract: For splicing two optical fiber cables placed within a grooved dielectric support, centering and alignment of the fibers are carried out by means of centering pins inserted in longitudinal openings of an annular flange rigidly fixed to a terminal connector forming an extension of the grooved dielectric support, at least one of these openings being located at a distance from the cable axis which is greater than the radius of the cable.

Abstract: A head for the simultaneous laying of optical fibers within a grooved cylindrical support rod comprises a hollow tube through which the support rod is capable of passing longitudinally, a draw-ring rigidly fixed to and in axial alignment with the tube. A central opening of the draw-ring has an internal flange provided with radial projecting portions each adapted to rest on the bottom of one groove of the support rod. A member for inserting the optical fibers within the grooves of the support rod has a central opening which is in alignment with the central opening of the draw-ring and through which the support rod is displaceable in continuous translational motion.

Abstract: An alarm-triggering device for the receiver of an optical-fiber transmission system including in series a filter which has a passband located externally with respect to the band of frequencies employed for optical-fiber transmission and the input of which is connected to an avalanche photodiode, an amplifier, a rectifier, a voltage comparator circuit, and alarm-triggering circuit.

Abstract: A machining tool comprises an annular structure having the same number of teeth as there are grooves to be machined, arranged radially in the structure, each tooth carrying a pin engaged in a curved slot. It also comprises a locking device constituted by a ring occupying a recess in the structure and a system of pawls carrying fingers which penetrate into the curved slots of the structure. It also incorporates a collar for controlling the locking device.

Abstract: An improved solid-electrolyte tantalum capacitor for decreasing the danger of tantalum capacitors fires. An opening is provided in the external protection of the capacitor to allow the evacuation of the solder providing the contact between the cathode lead and the cathode when molten.

Abstract: A transmission cable using optical fibre for conveying the information consists of fibres loosely laid in helical grooves of a core so that the fibre will undulate within the groove due to over-length given by pretwisting of the fibre and curvature of the groove flanks. Reduction of the contact surface between the fibre and the core improves the electrical characteristics and reduces the sensitivity of the cable to mechanical stress.

Abstract: A method for testing a digital data transmission line connected between two modems, including the steps of transmitting a test message from the first modem to the second modem, comparing the received message with the standard test message to determine errors, transmitting a test message back to the first modem along with the error message determined from comparing the received test message with the standard test message at the first modem. The error signal transmitted to the first modem and the error detected there is interpreted to determine the error in the transmission.