Abstract: A multiplexing process in an asynchronous transfer mode telecommunication network consists in placing a payload in a series of cells supporting the same logical channel a series of data containers supporting the same logical channel, each container including a load that is a quantity of data greater than the payload of each cell. In one preferred embodiment the payload of each container is composite. It includes conventional synchronous digital channel samples and data micropackets each of which has a label indicating a logical channel and the length of the packet. Applications include ATM telecommunication networks.

Abstract: An installation for detecting the presence of helium in a fluid circuit, the installation including a tapping member constituting a volume comprising a first internal space and a second internal space separated from each other by a semi-permeable partition through which helium can pass, the first space of said tapping member being inserted in series in the fluid circuit, the second space being connected both to a gas source via an orifice having an adjustable aperture, and also to a pumping member via a pipe, the flow pumped through the pipe conveying the flow under viscous conditions towards a feed member connected to a helium leak detector.

Abstract: A molecular drag pump comprising a rotor and a stator, the pump being of the type including at least alternating finned stages of the rotor and of the stator, and in which the rotor is bell-shaped, while the stator includes at least one external portion carrying the stator fins and at least one internal portion penetrating into the bell-shaped rotor, said internal portion closing the pump at its delivery end and including a flange-forming external peripheral rim, wherein said external portion of the stator carrying the stator pins is made up of two half-stators that meet in a diametral plane, each half-stator comprising a single piece and being positioned axially by having a bearing surface situated at its end remote from its suction end that hooks into a complementary circular groove of said internal portion of the stator, and wherein the outside diameter of the first finned stage of the rotor at its suction end corresponds, ignoring operating clearance, to the outside diameter of the external portion of the

Abstract: A secondary pump unit comprising a mechanical secondary pump and a cryogenic trap, wherein the cryogenic trap forms a ring surrounding the outside of the mechanical secondary pump at its intake end, and the trap is enclosed in a casing defining, in parallel, the intake opening of the mechanical pump and of the cryogenic trap.

Abstract: In a time division multiple access point-to-multipoint transmission network, data is transmitted from a central station to local stations in multiframes containing a plurality of frames and a single free period allowing transmit time measurements and reflectometry measurements. Data is transmitted from the local stations to the central station in the form of multiframes containing a plurality of frames and a single free period allowing transmit time measurements and reflectometry measurements, each frame including subframes sent by the local stations, and each local station sending one or more of the subframes contained in a frame. The multiframes are constructed in a way that underuses the data sources, to obtain free periods between the frames, and by time-shifting the frames to construct a single free period per multiframe. Applications include telecommunication networks.

Abstract: In a method of routing cells in an asynchronous time-division multiplex switching network interconnecting input switches and output switches via switches, each input switch can be connected to each output switch via at least two paths. The transmission of a sequence of cells of a given call between one input switch, called the call input switch, and one output switch, called the call output switch, comprises the following steps:determining the set of N possible paths between the call input switch and the call output switch,setting up N sub-connections corresponding to the N possible paths,in the call input switch, systematically and equitably distributing the cells of the sequence to the N sub-connections, andin the call output switch, assembling the cells of the sequence to reconstitute the sequence.

Abstract: A simple implementation of a high-capacity switching matrix includes four input functional modules each having one input and four outputs and four output functional modules each having four inputs and one output. A broadcast network has 16 inputs connected to the 16 outputs of the input functional modules and 16 outputs connected to the 16 inputs of the output functional modules to broadcast four signals from each input functional module simultaneously to each output functional module. The broadcast network includes four send subsystems each sending four optical carriers at four different wavelengths .lambda..sub.1, . . . .lambda..sub.4 and four receive subsystems each receiving four optical carriers at these respective wavelengths. The broadcast network further includes four optical buses each connected to a respective input of a receive subsystem and to a respective send subsystem so that the jth bus for j=1 through 4 receives from the kth send subsystem the carriers at the wavelengths .lambda..sub.

Abstract: In a method of transmitting asynchronous time-division multiplex transmission link control information the control information produced by the control process is transmitted in the form of control cells. At the transmitting end the control cells conform to a format enabling them to be identified as such, the empty cells to be transmitted on the link are identified and any control cell to be transmitted is substituted on the link for an empty cell which is not transmitted. At the receiving end the control cells are detected and extracted to be used in the control process and are replaced as necessary with empty cells.

Abstract: The bearing has a fixed portion, and a moving portion, and includes a passive magnetic abutment composed of a fixed element secured to said fixed portion, and of a moving element secured to said moving portion. The bearing further including a passive magnetic centering bearing which is coaxial with said passive abutment, and which is composed of a fixed element secured to the fixed portion, and of a moving element secured to the moving portion, the passive abutment externally surrounding the passive centering bearing, the passive abutment having axial stiffness k.sub.ab, radial stiffness k.sub.rb, a mean radius R.sub.mb, and an inside radius R.sub.ib, and said passive centering bearing having axial stiffness k.sub.ac, radial stiffness k.sub.rc, a mean radius R.sub.mc, and an outside radius R.sub.

Abstract: The relates to locking the phase of output signal (Ys) relative to an input signal (Ye). A first frequency correction signal (Yr1) is obtained by integrating a signal representative of an error of said phase relative to a reference defined by the input signal. It then cooperates with a second frequency correction signal (Yr2) to correct the frequency of an oscillator (VCO) supplying the output signal. The second frequency correction signal is obtained with the help of an adjustment signal (Yg) by integrating an error of the first frequency correction signal (Yr1) relative to said adjustment signal. The adjustment signal may itself be obtained by integrating a frequency error. The invention is particularly applicable to telecommunications systems.

Abstract: A tracer gas leak detector includes a mass spectrometer delivering a signal q proportional to the partial pressure of the tracer gas in the spectrometer, wherein the detector further includes apparatus for obtaining from the signal q a signal ##EQU1## where A is an adjustable amplifier coefficient and dq/dt is the time derivative of the signal q, and apparatus for obtaining an output signal referred to as the processed signal of the form q.sub.t =q+q'.

Abstract: This protocol consists in, among other things, updating in all the terminals and in all the nodes of the telecommunication network which a given call concerns a matrix representing the status of each terminal (TA, TB, TC) which is a party to the call in question vis-a-vis each connection (C1, C2, C3) set up for the call in question. This matrix distinguishes a plurality of fine states within the active state of each of the terminals and the nodes that this call concerns. This matrix is generally updated by means of a message which is broadcast throughout the network when an operation is executed in one of the terminals and modifies: the state of this call, or of a connection set up for this call, or of a terminal participating in this call.

Abstract: In a method of allocating carrier frequencies for simultaneous transmission of a plurality of modulated signals the carrier frequencies are chosen to satisfy the equation:f=(2p+1)n.+-.kwhere "p" is an integer number specific to each carrier frequency, "n" represents a given frequency bandwidth and "k" represents a given frequency bandwidth less than "n" and possibly a null bandwidth. The value of n is chosen to be sufficiently large relative to the width of the frequency channels occupied by the modulated signals that if k.noteq.0 second order composite distortion occurs outside the channels. Alternatively, if n is insufficiently large relative to the width of the channels (or the widest of them if the channels are not all the same width) the capacity of the transmission system is such that second order composite distortion occurring inside the channels is offset sufficiently relatively to the carrier frequency not to disrupt the transmission of the respective signals.

Abstract: A transactional protocol allocates write intention locks at the time of access to a transaction modifying data stored in a memory. These locks do not prohibit the allocation of read locks to other transactions. The other transactions can therefore read the old values of the variables until the new values are written into the memory when the transaction is closed. The time for which reading of data being modified is prohibited is restricted to the time to write the new values into the memory. This protocol is of particular benefit if the memory is a volatile memory and the modified data is backed up in another, non-volatile memory. In this case, the protocol further keeps up-to-date a table stored in the non-volatile memory and containing the identifiers of current transactions. This table is used to ensure that the data is consistent after failure of the volatile memory and contributes to maintaining a minimal time of prohibition of reading of data being modified.

Abstract: A system for transmission on an optical link by modulating an optical carrier suitable for video-communication cable networks, includes devices for increasing the modulation of the optical carrier, such as increasing the intensity modulation. The system is particularly suited for the case in which a high input optical power is coupled into the optical link. Also, the modulation can be increased from a null value if the modulation is other than intensity modulation, in order to prevent or to reduce phenomena degrading transmission quality associated with the Brillouin effect.

Abstract: The invention relates to a switching network enabling a plurality of bothway I/O links to be interconnected. In one embodiment of the invention, the network includes at least two nodes, each node possessing not more than k incident I/O points, k.gtoreq.2, n sets of k extended I/O points, n.gtoreq.2, and extension/concentration devices enabling each of the k incident I/O points to be connected to one of the extended I/O points of each of the n sets. Each bothway I/O link is capable of being connected to one of the incident I/O points of one of the nodes, and each node is associated with a bothway switching matrix having k I/O ports. The nodes are interconnected in pairs by first and second one-way switching matrices each having k input ports and k output ports.

Abstract: A rotary assembly comprising a stator and a rotor of axis .DELTA., rotary drive means, radial support means, and an active magnetic axial abutment comprising a magnetic circuit in two portions, namely a fixed portion, and a moving portion, the two portions being separated from each other by two parallel plane air gaps, each portion of said magnetic circuit being circularly symmetrical about axis .DELTA., and having the shape of an open channel-section extending about said axis .DELTA., the open ends of the two portions of magnetic circuit facing each other, an electrical coil being received in the inside annular space of the fixed portion of the magnetic circuit, wherein a drive winding secured to said axial abutment coil and received in the inside annular space of the moving portion of said magnetic circuit co-operates with permanent magnets fixed to the moving portion of said magnetic circuit, and facing said drive winding.

Abstract: A digital bit stream from a first synchronous link is timed by a first clock and is to be sent over a second synchronous link timed by a second clock. A device for justifying the bit stream at regular intervals includes a buffer memory. Respective pointers supply buffer memory write and read addresses. A value indicating how full the buffer memory is is calculated and compared to first and second threshold values to produce a justification command signal. The first and second variable threshold values are determined according to the phase difference between the header of a row received from the first link and the header of a row sent at the same time on the second link. The device finds an application in gateways at the input of and in telecommunication networks using the synchronous digital hierarchy.

Abstract: An add-drop optical spectrum-division multiplexer for dropping a drop multiplex from an incoming multiplex signal and for adding an add multiplex into an outgoing multiplex signal. The multiplexer includes a demultiplexing device for separating a number of optical carriers from the incoming multiplex signal and for selecting drop carriers which constitute the drop multiplex as well as through carriers which are to be output as the outgoing multiplex signal. The multiplexer further includes an apparatus for selecting a certain number of add carriers from the total number of carriers of the add multiplex, and a coupling device and wavelength converter for allocating fixed wavelengths to the signals which modulate the through carriers and the add carriers.

Abstract: A device for filtering positive dejustification jitter of a digital bit stream includes a phase-locked loop for slaving the timing of a signal representative of the read timing of a buffer memory into which the dejustified digital bit stream is written to the timing of a signal representative of the write timing of the buffer memory. The device applies low-pass filtering and determines the actual justification rate of the digital bit stream and deduces therefrom the difference justification rate, i.e. the difference between the actual rate and a nominal justification rate of the digital bit stream. It systematically eliminates phase shifts due to positive dejustification from the signal representative of the buffer memory write timing, regenerates phase shifts of the signal in numbers corresponding to the nominal justification rate, and regenerates phase shifts of the signal in numbers corresponding to the difference justification rate and smooths the phase shifts.