Abstract: A remote surveillance utilizing signalling incorporated in traffic and concerns more particularly digital links using a prohibited configuration code for the line signal. The purpose is to produce a system consisting of periodically incorporating an interrogation identifier containing a prohibited configuration in the line signal at the transmitter terminal, recognizing the interrogation identifiers as they pass through equipment under remote surveillance, modifying one interrogation identifier out of r by equipment that has remote surveillance data to be transmitted, using the interrogation identifiers reaching the receiving terminal intact to determine those time slots occupied by the remote surveillance signal and extracting the identifiers occupying these time slots for decoding the remote surveillance.

Abstract: A data and signaling time slot transfer and processing system for a set of multiplex lines comprises a switching matrix. Its inputs are connected to n multiplex lines by switching matrix input lines. There are m serial communication controllers each connected to an input register and an output register. The outputs of the switching matrix are connected by m output lines to the input registers. Its inputs are connected by m input lines to the output registers. The matrix outputs are also connected by n switching matrix output lines to multiplex lines. A composite clock signal is applied to all the input and output registers. A further clock signal is applied to the controllers, for the purpose of changing the information reception and transmission bit rates, the information having a bit rate of 64 kbit/s and the multiplex lines functioning at 2.048 Mbit/s.

Abstract: A signaling terminal system for the CCITT No. 7 common channel signaling system comprises groups of terminals and a terminal control unit for each group. Each terminal is connected by a bidirectional link to the switching network of a telecommunication exchange. Level 3 of the exchange comprises a central control unit and a main memory. The terminals and the terminal control unit are connected to level 3 of the exchange by a system bus. Within each group, each terminal is connected to the system bus by an access circuit and to the terminal control unit by an interchange circuit. Pairs of terminals may share a common access circuit and a common interchange circuit.

Abstract: A valve which opens on reduced pressure comprises: a hollow body (1) divided into first and second portions (2 and 3) by an internal partition (4), with the first portion being provided with a first opening (5) for connection to an enclosure to be evacuated and with a second opening (6) for connection to the aspiration side of a vacuum pump; a moving valve plate (7) disposed inside the first portion; a spring (8) urging the valve plate to close the first opening; a rod (10) having one end connected to the valve plate and passing through the internal partition; and a piston (b 11) which is connected to the other end of the rod, and which divides the second portion into a first chamber (13) and a second chamber (14) which are sealed from each other, the first chamber being on the rod side of the piston and being in communication with the outside (19), and the second chamber including an orifice (22) for communication with the outside, which orifice is fitted with closure means (23), the second chamber further i

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 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 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: In a system for exchanging encoded messages between stations, each station comprises a control unit and a connection module connected to a signaling link and a data link, the signaling and data links being serial multiplex links synchronized by a general timebase. Each connection module sends over the signaling link, in a time slot of a frame, four status bits, one reservation bit and one standby bit and receives in its time slot a calling bit from a calling station, or sends a calling bit in the time slot of a called station. The length of the data messages is equal to an integer number of frames, this number having a predetermined maximum value beyond which a watchdog timer disables sending over the information link. Each message is sent in its entirety and without interruption.

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 level of the signal present on the telephone channel is evaluated at successive time intervals. Those evaluated signal levels which lie within a given range of noise levels are selected and they are expressed in terms of r discrete values in said range. A count is maintained for each of said discrete values indicative of the frequency with which it is selected in comparison with the frequency with which the other discrete values are selected. The discrete value having the highest count, i.e. the most frequently selected discrete value, is considered to be indicative of the level of noise on the telephone channel in question.

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.