Abstract: A method of de-polluting a helium leak detector in which a pumping station and a gas analyzer (5) connected to the pumping station via an air inlet duct provided with an insertion valve (6). The pumping station comprises a sliding vane rotary vacuum pump (1) comprising a rotor (7) and a stator (8). The assembly is placed in a sump partially filled with oil (10). A suction duct (11) connects the interior of the stator to the exterior of the sump connects exhaust channel (12) connecting the interior of the stator to the interior of the sump which is in communication with the exterior via a point (14) of the sump which is situated above the oil level. The pumping station further includes a link duct (15) having a fastening (4) for connection to an apparatus to be tested at one end and having its other end connected to the suction duct via a pump isolating valve (2).

Abstract: A flexible printed circuit (1) has conductive tracks (2) each having one end constituting an electrode in a linear arrangement of electrodes. The back of the printed circuit in the vicinity of said arrangement of electrodes is pressed against a convex structure and an insulating film (3) covers printed circuit away from the electrodes in order to ensure a desired gap between the electrodes and the surface of a recording medium (11) pressed against the head. The head is particularly applicable to forming an electrostatic latent image which is subsequently transferred to some other recording medium.

Abstract: A component fixing machine for hybrid circuits including heating station (5) and a cooling station (6) which are both mounted on a common carriage (17) which is driven in translation back and forth under a fixed station (4) for holding the substrate (1) above the carriage.

Abstract: A timing recovery circuit for synchronous data transmission using a signal which, in the baseband, is formed by a succession of two-level signal elements, without overlap, and of duration T, able to take one of the four forms defined by the functions: ##EQU1## comprises a transition selection circuit. This circuit selects transitions in the received signal, in the baseband, separated from those which immediately precede them by a time-delay situated in an arbitrary range. This range brackets a symbol duration of between 3/4 and 5/4 times, exclusive, the duration of a signal element. A timebase which is synchronized on the transitions selected by the selection circuit delivers the signal element recovered timing.

Abstract: A concentrator is connected to a line test bus (BL) and a terminal test bus (BT) which are common to a plurality of concentrators. A concentrator is constituted by a plurality of terminal units (UT1 to UTm) connected to a spare bus (BS) internal to the concentrator. Each terminal unit includes a plurality of terminals (T1 to Tn) with associated terminal relays (R1 to Rn), a control logic circuit (LOG) and an isolating relay (RI) connected firstly to the spare bus, to the line test bus and to the terminal test bus, and secondly to the terminal relays by line wires (LA1, LA2) and junctor wires (LJ1, LJ2). In one of the terminal units of the concentrator, one of the terminals is a spare terminal (TS) and its associated terminal relay is a spare relay (RS) and the spare relay is directly connected to the spare bus.

Abstract: A high vacuum rotary pump comprising a rotor (3) mounted in a stator (1) having a suction end (5) and an exhaust end, the exhaust end being pierced by an exhaust orifice (6) intended for connection to the suction end of a primary pump, said rotor being drivable coupled to a motor (8, 10) housed in a sleeve (11), said sleeve extending the exhaust end of said stator and having the same internal pressure as the exhaust end of the stator, the rotating members of said motor and rotor being supported by bearings (12, 13), and the far end of the sleeve from its end adjacent to the stator being closed by an end plate (14), the pump including the improvement whereby an orifice (16) for rapidly returning the stator to atmospheric pressure is provided in said sleeve in such a manner as to avoid oil vapor being introduced into the stator from the primary pump when the pump is stopped, said orifice being provided with a valve which is closed during operation of the pump and which is open only when the pump is stopped.

Abstract: The header comprises: a plurality of optical connector supports (3) each having an elongate body in the form of a hollow finger (30) which is equipped at one end with an optical connector member (31) for interconnecting a pair of connection end fittings, and on one side with a coil former (32) for receiving the single fiber (55) of said cable (5) which has its end fitting (56) connected inside said finger to said connector member (31); and a magazine (1) comprising a plurality of individual cavities (10) for each of said optical connector supports (3) whose connector members constitute optical accesses to the individual fibers of said cable, said accesses being available in a "front" face (1C) of said magazine. It thus becomes possible to make optical connections to any of the individual fibers without affecting links passing via connections made to any of the other fibers.

Abstract: In a QPSK system using one cycle of a squared-off sinusoid per Baud period to represent the data dibits, the following are disclosed:(1) a direct detection circuit using samples taken only during the second and third quarters of the Baud period;(2) timing recovery by recognition of the opposite polarity of any QPSK signal compared to a half-Baud-delayed version of itself; and(3) an encoding scheme wherein only one of the two dibits is differentially encoded.

Abstract: Echoes occur in telephone systems whenever signals in one channel of a two way conversation spill over into the other channel. The present echo canceller is particulary intended for use with a hands free telephone where the spill over is in the form of an acoustic echo from the loud speaker (2) to the microphone (1). The signals are sampled at a rate 1/T and are made available as digital samples. A synthetic copy of the echo signal is generated by means of an adaptive digital non-recursive time domain transversal filter. Instead of tapping the filter at unit time intervals equal to the sampling period T in the conventional manner, the filter is tapped at unit intervals equal to twice the sampling interval. For a given amount of calculation in the filter, this has the effect of doubling the length of the filter's impulse response.

Abstract: Oil-sealed vane pump has a stator and a rotor assembly housed in an oil-filled tank, said stator comprising an oil injection orifice, a suction port connected to a tank inlet pipe and a discharge port opening into said tank, said discharge port being provided with a check valve, said check valve being mounted in a spot facing in the stator and said tank further comprising a discharge outlet. The stator is provided with at least one slot opening into the spot facing.

Abstract: The invention concerns exchanges switching telephone traffic, and in particular digital exchanges which have tie-lines passing therethrough. The exchange comprises control units (UC) and terminal units (UT) which are microprocessor controlled and which are connected to a switching network (RCX) by two-way multiplex links (MU). Some of the terminal units are connected to handle respective PCM junctions. At least one of the terminal units is a mixer and separator unit (UTB) which receives the signalling channels and in particular the signalling channels associated with the tie lines. This mixer and separator unit serves to forward signalling channel information for the tie lines. The terminal units connected to PCM junctions which include tie lines send the tie line signalling to the mixer and separator terminal unit, and also receive said signalling from said mixer and separator unit for onward transmission over a destination PCM junction.

Abstract: An electronic subscriber junctor for connecting a subscriber line to a telephone exchange, comprising an output amplifier circuit connected to the line, first means for generating a compensation voltage proportional to a common mode voltage occurring on the line and for providing a direct current proportional to a DC component of the line current, second means for obtaining a constant current, for algebraically summing said constant current and said direct current, and for supplying to the output amplifier circuit a first control current equal to said algebraic sum of the constant current and the direct current, third means for providing from said compensation voltage, via two connecting wires and on each wire, a second control current to the output amplifier circuit so as to compensate for longitudinal currents on the line, each connecting wire carrying the first control current and the output amplifier circuit delivering on each line wire a current proportional to the algebraic sum, on each connecting wire,

Abstract: The apparatus comprises a zero pass detector (2) for detecting zero passes in a voltage signal proportional to the line current to generate a pulse signal constituted by positive and negative rectangular pulses of equal amplitude and of width dependant on the duty ratio of the line signal, a pulse signal processor constituted by a saturable integrator circuit (4) connected to integrate the pulse signal and to deliver a triangular signal having a positive peak value which increases after ringing has been answered, a comparator (6) connected to compare the triangular signal with a positive reference voltage (+Vr) and to deliver a loop detected signal when the peak value reaches the reference value, the loop detected signal being applied to a bistable logic device (8) which serves to store the loop detected signal and to deliver an output signal from the apparatus based on the stored signal.

Abstract: In the manufacture of a semiconductor component, connection areas adapted to connect the component externally are formed by a metal array (3, 4) deposited on a conductive layer (6) of low melting point alloy, itself deposited on a metal temporary substrate (7). Each component chip (1) is placed in position and connected and then immobilized by means of a hardenable resin (5). The temporary substrate (7) is then removed by melting the alloy layer (6) to expose the surfaces of the connection areas (3, 4) for making external electrical and/or thermal connections to the encapsulated component.

Abstract: An indirect electrostatic printer is characterized in that the intermediate medium in the form of a dielectric tape (1) is mounted in an open loop defined by a supply reel (2), an auxiliary roller (4) over which its path doubles back and a take up reel (3), and in that said auxiliary roller (4) and an associated pressure roller (14) define a combined station (7) for simultaneously transferring and fixing the image on the final medium which is in the form of individual sheets (8), and said auxiliary roller and said pressure roller constituting, together with said tape (1), means for conveying the sheets to a copy delivery station (15).

Abstract: A hard vacuum pump of the type having a pump body (4) to which a multi-stage stator (3) and a multi-stage rotor (2) mounted on a shaft (1) are connected, said shaft (1) being driven by a motor and rotating in at least two ball bearings (5, 6) disposed in a sleeve (18) formed by an extension of said pump body (4), a dynamic molecular seal (7) being set on said shaft (1) at the body end of the sleeve (18), wherein the opposite end (11) of the sleeve (18) is closed, a nozzle (8) communicating with an outside source of gas being provided at said closed end (11), said pump body (4) also being connected to an exterior primary vacuum pump whereby said ball bearings (5, 6), and the rotor (9) of said motor are permanently swept by said gas entering via said nozzle and leaving via said dynamic seal, said gas flowing at a pressure intermediate between atmospheric pressure and the pump discharge pressure.The invention is used in microelectronics techniques.

Abstract: A digital frequency receiver connected to a processor for the recognition of multifrequency code signals received in signalling time slots and transmitted to the receiver in digital form by at least one time multiplex link. The receiver includes means (MO) for modulating the received signals with signals whose frequency corresponds to a code being used and which are supplied by a digital generator, means (FPB) for low-pass filtering the modulated signals and means (CL) for analyzing the energy contained in the spectrum of the signals received in the neighborhood of the frequencies of the code. The invention is particularly adapted for use in time-switched telephone exchanges.

Abstract: A group of terminal units (GUT) for a digital exchange having distributed control residing in control means comprising microprocessor control units (UC) which are interconnected by means of the exchanges' time switching network (RXA to RXD). The control units UC are connected to each other by a duplicated point-to-point link (RIT1, RIT2) and to the switching network by a coupler (AM) which is provided with a send/receive circuit that operates using a semaphore procedure. Each of the terminal units (UT) includes a control microprocessor (mp) connected to the switching network by a send-receive circuit (ER) using a semaphore, or question and answer, procedure. The terminal units (UT) are controlled by the control units (UC) by interchanging messages using a common procedure for all the terminal units. These messages are interchanged over channels in the links that make up the switching network of the exchange.

Abstract: A security system for an exchange having distributed control. Exchange control is distributed among a plurality of microprocessors and in microprocessor terminal units connected to a time-division switching network. The security system is organized on three levels: (I) a first level comprising security means in each microprocessor for detecting faults and for taking decisions concerning current processing; (II) a second level comprising means for managing said security blocks and for switching over from one block to another and re-configuring the links affected by the switchover; and (III) a third level comprising means for managing the microprocessors of the exchange control means and the two point-to-point links, said third level means comprising two identical peripheral control units controlling respective mass memories each containing a copy of the software needed to run the exchange.

Abstract: A time division exchange controlled by a plurality of control units (UC, UCP), terminal units (UT) and markers (MQ). The control units are connected to each other and to the markers by a data interchange network (RIT) of a type which provides point-to-point serial connections. The network is duplicated and operates using a semaphore procedure. Access to the network is controlled by a duplicated controller (DR). Two-way multiplex links (LX) are provided over switched paths which could be used for voice or data switching. They are also used using a semaphore procedure and serve to provide connections between the control units and the terminal units. These connections are established via the exchange switching network. The invention is applicable to telephone switching or to data switching at subscriber or trunk level.