Abstract: Ringing current is a high-voltage, low-frequency signal which is sent from a telephone exchange via a pair of wires to ring a bell in a distant telephone. It is becoming common practice for distant telephones to be connected via a carrier connection and the present invention provides a device for conveying a high-voltage low-frequency signal along such a carrier connection. The device comprises a sender part and a receiver part connected together by the carrier connection. The sender part on/off modulates one of the carrier frequencies used in the connection at twice the rate of the low-frequency signal. The receiver part detects the on/off modulation and uses it to connect alternate opposite voltages delivered by a voltage multiplier circuit to a line connected, for example, to a telephone bell.

Abstract: Low-level, wide-band signals e.g. for use in telephone transmission are switched in a matrix device. The overall matrix is subdivided into elementary matrices of smaller size and each inlet of the overall matrix is provided with a selector for selecting the appropriate elementary matrix which contains the desired cross-point. This subdivision is performed as is conventional to reduce interference and attenuation from echos generated in the unused portions of the matrix, but it has the drawback of increasing the complexity of switch control, two selectors and one cross-point needing activation in the place of a single cross-point. The present invention provides selectors which are sensitive to the conductive state of the cross-points to which they are directly connected to repeat the conductive condition to their respective inlet of the overall matrix, thereby simplifying switching control without sacrificing transmission characteristics.

Abstract: The invention consists in an equalization system with two sections, one at each end of a transmission channel. The section at the transmission end adds control signals to information signals to be transmitted over the line. The section at the reception end generates control signals identical to those added at the transmission end and in phase with the control signals received over the transmission channel, which are separated from the received information signals by means of a first transversal filter with controllable weighting coefficients, the reciprocal transfer function of the transmission channel being synthesized from the locally generated and the received control signals by means of a second transversal filter with controllable weighting coefficients, equalization being achieved by means of a third transversal filter with the same design and same weighting coefficients as the second transversal filter. The invention is applicable to the transmission of data over telephone lines.

Abstract: The present invention relates to a facsimile transmission installation adapted to allow rapid transmission of the contents of forms. In accordance with the invention, various types of blank forms are memorized and the transmission equipment includes a comparator connected to a memory and to an analysis circuit and allows the transmission of a facsimile signal which represents only the data added on the analyzed filled-in form and the reception equipment includes a text regenerator which operates from a transmitted facsimile signal and from a signal which comes from its memory.

Abstract: An object pattern to be inspected, such as a printed circuit board, and a reference pattern are scanned synchronously by respective cameras. The outputs of the cameras are compared and a fault signal is produced when the outputs do not coincide.

Abstract: The present invention relates to a printing bar with a plurality of styli (10) for printing an image.It includes a first network of conductive tapes (1) insulated from one another and in which one end of each of them forms a printing stylus (10) and n diagonal matrices for addressing the styli whose columns are formed by the conductive tapes (1) of this first network and are fed via resistances (R) in electric contact with the tapes (1) of said first network and in which the rows common to the n matrices are formed by conductive tapes (7) of a second network and are connected to the columns via diodes (D) connected in the columns or in the rows.Application: a facsimile transmission installation.

Abstract: The invention relates telecommunications. It concerns in particular the cutting of optical fibre. It provides a hand tool which is generally shaped like pincers whose two legs move apart during operation, the optical fibre being fixed to each of the free ends of the legs which stretch it and press it against a rounded forming part fixed to one of the legs while a knife comes up to the forming part to start breaking the fibre by scoring it, all these operations being controlled by operating a single trigger lever. It applies to the forming of connections at the ends of the optical fibres.

Abstract: The invention is characterized by the use of electronic scanners independently controlled by a control unit, said scanners cyclically scanning in an autonomous manner the matrices of the contacts which are assigned to them and the control unit cyclically observing the scanners so that when a scanner detects the change in state of a contact, the control unit collects from said scanner the georgraphical data of this contact and causes, during a determined time the display of the number of said contact and possibly signals the category to which it belongs. This signalling can also, according to its category, be accomplished by an acoustic alarm.

Abstract: A device for detecting errors in digital transmission systems which use a line signal whose digital running total is bounded and can only take n distinct states, e.g. a high data rate digital transmission system. The error detection device comprises a synchronous up/down counter with k bistables which give, in real time, the digital running total, and an end decoder formed by logic gates and which is sensitive to the up/down counter overflowing from either of its upper or lower limit values, the number k being an integer which satisfies the inequality:2.sup.k >n.gtoreq.2.sup.k-1.

Abstract: The invention consists of providing two lubrication circuits, a main circuit for lubricating the compression chamber and the various components of the compressor when operating under load and a secondary circuit for lubricating the components disposed on the suction side when operating under no load.The invention is used in air compressors.

Abstract: The present invention concerns the transmission of information, and consists in a continuous regulator responsive to the amplitude of a pilot tone included in the signal whose level is to be regulated, including a variable-gain quadripole through which said signal is passed, an automatic gain control loop including a circuit controlling the gain of the quadripole, and an auxiliary feedback loop through which the control circuit also controls the automatic gain control loop. The regulator is applicable with advantage to transmission systems.

Abstract: A circuit permits the output voltage of an amplifier to be limited for certain ranges of its input voltage by causing the amplifier to saturate for said ranges of its input voltage by reducing the power supply.The invention is applicable, for example, to eliminating or levelling the components of a signal whose amplitude lies within a certain range, without affecting any other components.

Abstract: The invention relates to high-security time bases. A time base comprises three synchronized generators which each deliver a clock signal 2h or a synchronizing signal Sy used for synchronizing frames. Each generator includes an oscillator driven by a phase comparator which receives the three clock signals and by an internal locking circuit which receives a signal connected to the external synchronizing signal and/or a signal connected to the synchronizing signal Sy inherent to the generator, the synchronizing signal Sy being synchronized by a majority circuit which receives the synchronizing signals Sy from the three generators. Application to data processing installations and in particular to telephone exchanges.

Abstract: A circuit board is received in a cut-out in a surrounding frame. The circuit board has a peripheral ground conductor which is connected to the surrounding frame by the conductive teeth of an assembly of combs. The non-toothed spines of the combs are arranged along the margins of the surrounding frame and the teeth are inclined. They are preferably inclined in the plane of their spines. Such an assembly could be used for the amplifier of a telephone repeater assembly.

Abstract: A very high voltage generator switchable between n levels for supplying a capacitative receiver, such as the screen of a polychrome display tube, and comprising a high voltage DC power source suitable for delivering two extreme levels of voltage straddling the n DC voltage levels. The power source is connected to the receiver via at least one series assembly of transistors for each direction of conduction between the power source and the receiver; each series assembly is associated with a control channel for the transistors elaborating an image signal of the error voltage between the value of voltage at the terminals of the receiver and the required level for the operation of each assembly as a switch, at least one of the control channels also comprising a modulator in which the image signal modulates the voltage of an oscillator for the operation of the corresponding assembly as a switching and regulating circuit connected in series with the receiver.

Abstract: The present invention relates to a method of connecting optical fibers by ing a capillary tube which is flared at both ends. The capillary tube is formed so that its bore is cylindrical along at least half of its length, the fibers are inserted into the bore by vibration until their respective end faces come into contact with each other and the capillary tube is then heated to its softening point (at least at its ends) and allowed to cool to obtain a tightening of the ends of these fibers.

Abstract: A terminal is connected by a transmission link to a computer coupler. The rminal has a reader for a worker's card or badge. A number written on the badge is sent to the computer for verification and is echoed back if OK. The return number is checked against the number sent and if still OK the badge number is displayed. Communication takes place over two telephone lines which may be taken from amongst pre-existing telephone lines in a work location. Other data such as time and total hours worked may be displayed by the terminal once a badge has been verified.

Abstract: The invention relates to transmission systems and in particular to level regulators controlled by a pilot tone and used in such systems to correct variations over a period of time in the attenuation of the transmission system.The subject of the invention is a level regulator governed by a pilot tone whose gain control circuit locks in a mean position where there is a very low or zero value detected for the pilot tone. This locking is achieved by modifying the supply voltage of the error amplifier of the loop providing automatic gain control for the regulator.The invention is of particular application to cable transmission systems with repeaters.

Abstract: A millimetric wave high-pass filter is assembled from two axially-separate halves. Each half comprises a cast metal body having a channel which is divided to form two wave guides by means of a metal strip. The dimensions of the wave guides of the filter as a whole decrease towards a constriction at their centers while the strip is relatively thick at the constriction and tapers towards the ends. This configuration makes it possible to cast the filter in two halves with the body and the strip of each half being cast in a single piece. When assembled the halves meet at the level of the constriction.

Abstract: This invention relates to a method of encoding data by transitions in a binary sequence, as well as to a coder and a decoder using the method. In the method data is encoded as follows: a first value bit is encoded by a transition in the middle of the corresponding bit-time, but this transition is inhibited if there was a transition in the middle of the previous bit-time, a second value bit is encoded by a transition at the beginning of the corresponding bit-time, but this transition is shifted from the beginning to the middle of the bit-time if there was a transition in the middle of the previous bit-time.