Abstract: A molecular or turbomolecular type of pump comprising a stator (2) and a rotor (3) rotated by a motor (7), the stator having a first zone overlying the rotor and in which gas is admitted, and a second zone adjacent to the drive motor and cooled by a flow of fluid (8), the pump being characterized in that the first zone is provided with heater (12) for maintaining the temperature of the first zone above the condensation threshold of the gas being admitted, with the first and second zones being separated from each other by a thermal impedance element (13).

Abstract: The method enables transmission of a digital service channel by means of the parity channel of a digital bit stream transmitted in a parity checking code with parity words inserted at specific times by modifying certain parity words violating the parity checking code parity law. It consists in modifying spaced groups of even number of consecutive parity words so as not to disrupt analog detection of line errors. A digital service channel insertion circuit is included among the component parts of an MBIPIC type encoder whereby the data of a digital bit stream is transmitted by consecutive code words each formed of a block of data bits completed by a parity bit and an inversion bit.

Abstract: The invention relates to cooling integrated circuit packages (14) for surface mounting in a hybrid circuit. The invention provides a cooling method which consists in soldering the bottom of the integrated circuit package (14) to one side of the hybrid circuit substrate (10) and in soldering a heat-dissipating peg (30) to its other side. In order to do this, the bottom of the package is provided with a tinnable area and the substrate (10) is provided with two overlying tinnable areas on opposite faces thereof, said areas being put into communication with each other by at least one plated-through hole (31).

Abstract: A contact frame for an IC card reader including, in particular, guide means for guiding or positioning the card, together with contact elements for providing electrical connection with conducting pads on the IC card via which circuits are established to the apparatus including the IC card reader, the contact frame being characterized by the fact that it comprises an inner frame (7) of insulating material molded over the contact elements (4) for providing electrical connection to the IC card, and two extensions (17, 18) extending the substance of the inner frame (7) sideways towards the side edges of the card and beyond said edges, each of said two extensions carrying means (6, 19, 20) for defining the positions of two card-guiding slideways (21, 22).

Abstract: A contact frame for an IC card reader including contact elements for making connections with the IC card, the contact frame further including two electric contact blades (26, 28) carried by said frame and constituting an end-of-stroke contact (5), with one of said blades, a "fixed" blade (28), being coupled to the frame in such a manner that its stationary position relative to the frame is defined, while the other blade, a moving blade (26), is urged by a resilient force in a direction opposite to the direction in which a card is inserted into the reader, and is disposed in such a manner that a card being inserted comes into abutment thereagainst and imparts actuating motion thereto against its resilient force.

Abstract: A coding method uses a pseudo-logarithmic compression law approximated by a straight line segment curve. Its code word on n+1 binary digits, where n is a positive invariant integer, has a lefthand part made up of a variable number p of binary digits having the same value (1) corresponding to the rank number of the segment concerned in the compression law and a righthand part, which may be absent, determining the interval within the segment concerned.

Abstract: A method of starting series-coupled vacuum pumps comprising a primary pump (A) and at least one secondary pump (B) connected between the primary pump and an enclosure (E) in which a vacuum is to be established, the method consisting in starting the primary pump initially and subsequently starting the secondary pump when the suction pressure of the primary pump as reduced by rotation of the primary pump reaches an acceptable value, the method being characterized in that the pressure existing in the secondary pump is determined by using a physical magnitude related to the primary pump and following a law similar to the pressure law.

Abstract: An optical fiber (F) and a laser (L) are fixed on the top faces of two bases (EF, EL) which also have two facing vertical faces. A spring (4) presses these two faces against each other so as to create thrust friction. The thrust force is initially moderate in order to enable the relative vertical and transverse positions (GV, GT) of the two bases to be adjusted smoothly, after which the force is increased progressively in order to prevent relative displacement taking place while the two bases are being welded together by means of a YAG laser. The invention is particularly applicable to making optical transmission heads usable in optical fiber telecommuncations systems.

Abstract: The diffuser is made from N=2.sup.n light ducts divided into two sets of 1/2N ducts, with every other duct belonging to a different one of the sets. The two sets of ducts are helically wound in opposite directions but at the same helical pitch over a cylinder (1). Each duct in either set crosses over the 1/2N ducts in the other set, and couplers are provided at those cross-overs between any given duct and the 1/2N ducts of the other set having cross-over numbers 2.sup.q, where q=0, 1, 2, . . . , (n-1). The diffuser has stages each comprising 1/2N couplers, with each stage being disposed in a ring around the cylinder.

Abstract: A wafer of indium phosphide is disposed between two electrodes (102, 104) in a heated enclosure (100) into which ducts (110 and 112) admit nitrogen and ammonia. A high frequency electricity generator (108) forms a plasma between the electrodes which etches the exposed surface of the wafer. The invention is applicable, in particular, to forming semiconductor lasers emitting in the infrared for telecommunications purposes.

Abstract: An electronic circuit housing primarily applicable to undersea transmission-line repeater equipment includes a pressure-resistant tubular steel shell provided with water-tight end walls and containing a cylindrical assembly of frames having the shape of cylindrical sectors. Each frame is attached at one end to a radial flange of the internal shell wall and at the other end to an expandable collar provided with sliding wedges and locked by expansion in the internal shell wall. The fastening system facilitates mounting and accurate centering of the frames within the tubular shell, thereby guaranteeing a constant thickness and therefore uniform thermal conductivity of the interface between frame and tubular shell.

Abstract: A valve for a vacuum enclosure, the valve comprising a valve body (1) which is hollow about an axis .DELTA. and which opens out to the outside via two opposite end openings (24, 25) of the valve body, thereby enabling the valve to be inserted in a pumping circuit, the inside of said valve body being provided by closure means constituted by a strip (7) which is movable in its own plane, which plane extends perpendicularly to the axis .DELTA. said strip being provided with at least one opening (8) and being associated with two pay-out and take-up drums (9, 10) provided with drive means, said valve body being further provided with sealing means situated between the two drums and comprising a fixed gasket (15) fixed to the valve body and situated on a first side of the strip and a moving gasket system capable of moving parallel to the axis .DELTA.

Abstract: This power supply is intended, more particularly, for powering a user digital terminal from a remote terminal in an integrated service digital telephone network. It comprises a main D.C. electricity power source (10) provided with a protection device (11) causing its output to go to a high impedance state in the absence of a voltage across its terminals, and an auxiliary D.C. electricity power source (20) connected in parallel and in opposition with the main source (10) and provided with a current limiting device (20) which is normally tripped by the additional current which the main source (10) attempts to impose thereon.

Abstract: A rotary vacuum pump comprising a stator (1) and a rotor (2), the rotor being rotated inside the stator and the stator including a suction inlet (11) and an exhaust outlet orifice (12), wherein the suction end of the rotor carries at least one wheel (13) having sloping vanes (14) such that any solid particles that may be sucked in are projected thereby in a radial direction towards an annular stator collector tank (15) having a circular opening (16) opening out into the stator cavity (6) and situated in the plane in which said particles are projected by said vanes (14).

Abstract: A detector logic circuit restores the value 0 or .+-.1 of a ternary symbol converted into a signal on five levels 0, .+-.1 and .+-.2 as a result of class 1, type n=2 partial response transmission. Employing only binary logic circuits, it is connected to the output of a comparator which has four thresholds and which delivers a value representing the receive level by four binary signals. Two of these signals indicate positive overshooting of extreme and intermediate positive thresholds. The other two indicate negative overshooting of negative extreme and intermediate thresholds. The circuit delivers the values of the ternary symbols detected in the form of two binary components which are available at the output and stored for the duration of a symbol by two flip-flops. Both are generated by combinational logic devices of similar design utilizing OR and NOR gates.

Abstract: In a method of synchronizing synchronous digital bit streams each comprising bits each having the same duration, one of the bit streams is taken as a reference. This provides a basis for defining successive reference time intervals each equal to the bit duration. A plurality of timing windows are defined within each reference time interval. A second bit stream is subjected to a time-delay that can have a null or zero value. One of the windows is taken as a reference window on the basis of a required phase relationship between the reference bit stream and this second bit stream. The phases of the reference bit stream and the second bit stream are compared to determine a window containing the beginning of each bit of the second bit stream. The time-delay, if any, to be applied to the second bit stream is determined on the basis of this window.

Abstract: The circuit comprises two counters, one of which (A) operates at the irregular rate of asynchronous pulses applied to its count input (2), the other of which (B) operates at a regular rate which is not less than the average admissible rate for the asynchronous pulses, being clocked by an oscillator (5) providing pulses at a stable rate, a comparator (6) inhibiting the oscillator (5) each time the counter (B) catches up the counter (A) and a catch-up preventing control logic circuit (9) inhibiting the counter (A) whenever it tends to catch up the counter (B).

Abstract: The relocking device comprises a polyphase clock signal generator for producing n clock signals which are equally displaced in phase with respect to each other including the reference clock signal, and rephasing circuits each assigned to one data train to be relocked and each having the function of selecting that version of the clock signal which is most effectively locked with respect to the data train to be processed by means of a double-sampling circuit and a clock-signal selecting circuit addressed by a sequential scanning circuit controlled by a comparator. The rephasing circuits utilize said version for sampling precise values of the data contained in the data train concerned and regenerate said data train by resampling these values in synchronism with the reference clock signal.

Abstract: A synchronous digital cable transmission system comprises a transmitting terminal, intermediate regenerative repeaters and a receiving terminal. The transmitting terminal includes a data scrambler and a 6B/4T type binary-ternary line coder. The receiving terminal and the intermediate regenerated repeaters include a class 1 type n=2 partial response coding type receive signal shaping and filtering unit and a logic device for decrypting binary symbol superpositions resulting from the signal shaping and filtering processes. The receiving terminal also includes a 6B/4T binary-ternary decoder and a descrambler respectively compatible with the coder and the scrambler in the transmitting terminal.

Abstract: An installation for detecting a leak of a tracer gas, the installation comprises a mechanical primary pump (5) whose inlet is connected firstly to a part (9) under test via a first valve (2), and secondly to the outlet (17) of a turbo-molecular secondary pump (7) via a second valve (3), with the inlet of said turbomolecular pump being connected to the part under test via a third valve (4), and with a spectrometer cell (1) being also connected to the inlet side of said turbomolecular pump. The installation includes the improvement whereby said turbomolecular pump is constituted by two stages in series, with the connection between the two stages having an intermediate inlet orifice (16) connected thereto and also connected to the part under test (9) via a fourth valve (12), with the first stage connected to the spectrometer cell (1) having a high helium compression ratio, and with the second stage connected to the primary pump (5) having a high nitrogen throughput.