Abstract: The invention relates to a high-speed hard vacuum rotary pump. A hard vacuum rotary pump which includes a rotor (2) driven by a motor (20) disposed on the outside of the pump body and connected to the motor by a drive shaft (1) which is sealed by a grooved dynamic seal (8) is characterized in that said shaft is supported firstly by an outer bearing (6) disposed on the outside of the pump body (4) and secondly by an inner bearing (5) disposed inside the pump body and lubricated with grease. The invention applies in particular to molecular and turbomolecular vacuum pumps.

Abstract: A keypad caller which can be fitted into a conventional telephone set, includes a two-frequency oscillator (50) which emits two sinusoidal frequencies chosen from eight when a key (1, . . . 0) is depressed thereby selecting the frequency-determining resistors of the oscillator (50) and switching the (V.sup.+,V.sup.-) voltage supply to the oscillator 50 as well as switching a double switch (Q10, Q11) which switches the speech current.Applications: telephone telecommunications.

Abstract: A method of decoding a C.M.I. encoded binary signal, the method comprising the steps of: detecting the 0 to 1 transitions in the C.M.I. encoded binary signal; in detecting the 1 to 0 transitions in the same signal; in eliminating from the detected 0 to 1 transitions those transitions which appear one binary bit period after the immediately preceding 1 to 0 transitions; and in using the remaining 0 to 1 transitions to synchronize pulses of a duration equal to one bit period thereby obtaining, after inversion, a signal in NRZ-L code corresponding to the binary data contained in the C.M.I. encoded signal.

Abstract: The invention relates to a bar for printing an image. It comprises a stack of conductive plates which are insulated from one another in which one end of each forms a printing stylus and n diagonal matrices for addressing the styli whose columns are constituted by plates and are fed via resistors formed on the plates and whose rows common to the n matrices are constituted by electric conductors connected to the columns via diodes which are also formed on the plates.

Abstract: A hyperfrequency filter comprises a series connection of an inlet length of waveguide (1), a plurality n of resonant cavities (3, 4, 5) and an outlet length of waveguide (2). All these units are of rectangular cross-section and they are interconnected by coupling irises (16, 17, 18, 19). Each resonant cavity includes a dielectric tuning screw (13, 14, 15) for adjusting the resonant frequency of the cavity. Each tuning screw is located in the middle of one of the largest faces of its resonant cavity.The longer dimension a of the cross-section of each cavity is longer than the longer dimension of the cross-section of the waveguide lengths so that the optimum width of the coupling irises is substantially at its minimum possible value for a given set of design conditions on the other filter parameters. This has the effect of broadening the range of frequencies over which a given structure can be tuned without detrimental repercussions on the frequency characteristic of the filter.

Abstract: The space switch has an inlet series to parallel converter (1) arranged to take sequential data from the i-th time slot of each of a plurality of synchronized inlet multiplexes and apply them simultaneously to a parallel connection (11) within one time slot period. These time slots are written into one of two signal stores (2 and 3), e.g. sequentially. A control store (4) controls the order in which data is read from the signal store and re-assembled into outlet multiplexes by a parallel to series converter (5), thereby performing space switching between the stored time slots. The signal stores alternate between reading and writing, and each has a capacity equal to the product of the number (p) of inlet multiplexes (E1, . . . Ep) multiplied by a submultiple of the number of time slots to a frame. When the submultiple is greater than 1 there is a possibility of limited time switching within a sector of successive time slots, the number of time slots in each sector being equal to the submultiple.

Abstract: The invention concerns feeding current to a subscriber set. In addition to an isolation transformer (T) the transmission bridge includes a measuring circuit (4) connected to the subscriber line, and a receive circuit (7), with the measuring circuit connected to the receive circuit via an impedance adjusting circuit (6). The receive circuit is connected to a receive terminal (10) and is arranged to forward the signal received therefrom to the transformer. The bridge also includes a send circuit (9), likewise connected to the measuring circuit and receiving the signal at the receive terminal via a balance circuit (8) for cancelling the signal delivered by the send circuit while the subscriber set is receiving. Application to telephony.

Abstract: An image is printed on a photo-sensitive medium in the form of an array of pixels of various tone densities. The medium (11) is moved at a constant speed in a Y direction behind a screen (10). The screen (10) has columns of apertures (13) extending in the Y direction, with the different apertures of each column being of different sizes. A beam of light of constant intensity (preferably a laser beam from a laser generator (19)) scans regularly in an X direction over the screen. The laser beam is selectively deflected by means (40) to expose the photo-sensitive medium through a selection of the apertures of each column. Since the apertures are of different sizes the exposure is different through each size and thus dots of selectable size can be printed on any point of the medium. On any one scan, the light beam is capable of exposing any number of the apertures in each column, from none to all of them.

Abstract: A converter for converting input binary words into respective code binary words according to a given transcoding law, and application of the converter to reduced redundancy image transmission systems (e.g. facsimile systems). A main counter (3) is connected via an AND gate (5) to receive fast clock pulses from a fast clock (4). The main counter is capable of counting through all possible code words, and its count state is applied via parallel connections to a transcoder circuit (6) which obeys the inverse transcoding law to the given law i.e. it acts as a decoder of code words. First code words for encoding are applied in parallel from at an input (1) and are compared by a comparator (7) with the decoded versions of the count states as given by the transcoder (6). On identity the counting is stopped by means of the AND gate (5) and the count state that gave rise to the identity is stored in a buffer register (8) for application to outputs (2).

Abstract: An endless belt (1) transports supports (6) on which electronic components have been placed. The supports have a layer of solder which is to be melted to make electrical contact with the components assembled thereon. A hot plate (8) is arranged at the downstream end of the belt (1). In order to ensure uniform heating of the supports through the belt, the hot plate is provided with openings (10) in its plane, belt-contacting surface. The openings are connected to a vacuum pump (16) and the vacuum keeps the belt in intimate contact with the hot plate.The installation is particularly intended for use in assembling hybrid micro-circuits, whether using thin film technology or thick film technology.

Abstract: Data in the form of multi-value symbols is transmitted at a symbol rate 1/.DELTA.T. At the receiver a decision circuit supplies estimates of the transmitted symbols on the basis of the received symbols. The present invention concerns compensating phase noise after equalization if any of the received symbols and before application of the received symbols to the decision circuit (38, 39). The received symbols are in complex form with in-phase and quadrature components y.sub.k ' and y.sub.k " respectively. Phase noise is compensated by complex multiplication in a multiplier (36) of the received symbols by a complex coefficient.The invention is particularly applicable to quadrature modulation systems, but if only one channel is transmitted the quadrature channel can be simulated using the Hilbert transform of the one channel.

Abstract: Data in the form of multi-value symbols is transmitted at a symbol rate 1/.DELTA.T. At the receiver a decision circuit supplies estimates of the transmitted symbols on the basis of the received symbols. The present invention concerns compensating phase noise after equalization, if any, of the received symbols and before application of the received symbols to the decision circuit (38, 39). The received symbols are in complex form with in-phase and quadrature components y.sub.k ' and y.sub.k " respectively. Phase noise is compensated by complex multiplication in a multiplier (36) of the received symbols by a complex coefficient m.sub.km.sub.k+1 =[m.sub.k -.lambda.(v.sub.k -a.sub.k)y.sub.k *]exp[-iF.sub.k (.epsilon..sub.j)]where:.lambda. is a real coefficient;y.sub.k * is the complex conjugate of the symbol received at instant k.DELTA.T+t.sub.o (where t.sub.o is the instant taken as the origin of time measurements);v.sub.k is the symbol applied to the decision circuit at said instant;a.sub.

Abstract: An automatic exchange with a digital switching network, for the connecton of circuits or subscriber lines, said exchange comprising at least one central computer, signalling receiver and sender peripherals serving said circuits or lines, switching network marker peripherals, all said peripherals being placed under the control of the central computer, and said circuits or lines being connected to the switching network by digital channels in time division multiplex links characterized in that certain peripherals (UPI, LMQ) are piloted by the computer through the switching network RCX, the messages enabling computer (UCA) to pilot at least one peripheral (UPI, LMQ) being carried by a digital connection comprising two TDM-PCM links (MIC-C, MIC-P/MIC-M) connected to the switching network, the first said link (MIC-C) connecting to the computer, and the second (MIC-P/MIC-M) connecting to said peripheral (UP1/LMQ).

Abstract: A remote surveillance and fault location unit for installation in each pulse generator repeater in a digital transmission link uses a service signal added to the digital data signal conveyed by the link. Each unit comprises a receiver circuit (100), a time base (200) and a transmitter circuit (300) suitable for implementation as an integrated circuit. The units add data representative of the performance of the repeater at which they are located to the service signal which is then monitored at one end of the link. The remote surveillance and fault location unit comprises a receiver circuit connected to an input to the pulse generator repeater for receiving a service signal if one is present at the input, a carrier frequency and clock bit frequency recovery circuits, a transmission circuit having its output connected to a second input of the pulse regenerator repeater for transmitting a service signal corresponding to the received frame to which data has been added.

Abstract: A screened box comprises a rigid surround defining four side walls of the box, three of which have edge portions folded towards the outside. Two screening panels are placed one on each side of the surround, each with an edge portion inserted in an inwardly directed recess on the fourth of the aforementioned side walls. The other three edge portions of the screening panels overlap the outwardly folded edge portions of the side walls of the box. Clamping bars are fitted over each folded over edge portion and the overlapping edge portion of the screening panel.The box is intended in particular for housing electronic circuits.

Abstract: A leak detector comprises helium measuring means (6) for measuring helium sucked in by a sniffer (2) via a flexible hose (3) and a liquid nitrogen trap (5). A vacuum is maintained in the nitrogen trap (5) by a molecular diffusion pump (7) leading to a vacuum pump (18) which exhausts to the atmosphere. In order to speed the flow of gas, possibly including helium as a tracer element, along the flexible hose (3) most of the gas sucked in by the sniffer (2) is diverted from the inlet (4) to the nitrogen trap by a bleeder arrangement (12) connected to an auxiliary duct (11) which is itself connected to an intermediate point between two stages in the vacuum pump (18).

Abstract: The invention relates to a method of regenerating the modulation carrier wave of an original modulated signal (SL) which has symmetrical frequency components about the carrier. A phase discriminator (D1) which receives two image signals (SL, S11) of the original signal controls the frequency of a local oscillator (OL), the frequency spectrum of one of the image signals being inverted with respect to that of the original signal and the difference in frequencies between these two image signals being twice that between the local carrier and the carrier of the original signal. Application to the synchronous demodulation of a television signal.

Abstract: A digital sinewave generator can be used in digital equipment, e.g. instead of a local oscillator for modulation/demodulation of signals. If there is no simple relationship between sampling rate and the frequency of the sinewave, successive sample values must be calculated since storage of these values would be prohibitive. For a sinewave Re.sup.jk.phi. sampled at successive instants k=0, 1, 2, . . . etc. separated by a phase angle .phi., quadrature components A.sub.k +jB.sub.k =Re.sup.jk.phi. can be calculated using the algorithm:A.sub.k+1 =cos.phi.A.sub.k -sin.phi.B.sub.kB.sub.k+1 =sin.phi.A.sub.k +cos.phi.B.sub.k.Unfortunately it is impossible for cos.sup.2 .phi.+sin.sup.2 .phi. to be exactly equal to unity if calculations are performed with finite precision using an even number base, which as the effect of causing the modulus of a sinewave generated by this algorithm to tend exponentially to 0 to .infin.. The present invention overcomes this by using the above algorithm to obtain approximations A.sub.

Abstract: The invention relates to apparatus for monitoring the operation of electronic equipment having a plurality of circuits to be monitored, each of which has a fault indication terminal (24). In accordance with the invention, fault simulation means comprise a cyclic address counter (9) having a higher number of states than there are circuits to be monitored, and which is arranged to switch the binary fault indicating terminal of a circuit to its fault condition when indicating the address of the circuit. When indicating an address that is not allocated to any of the circuits, none of the circuits ought to respond. A check is thus performed on the operation of the fault simulation means itself. The invention is applicable to electronic equipment requiring a high degree of security in operation, e.g. a redundant time base. The equipment may be analogue or digital.

Abstract: A switching network is disclosed having a time-division or space-division multiplex incoming stage and outgoing stage in which a terminal unit of the incoming stage and a terminal unit of the outgoing stage form a terminal module (ME1, ME2 . . . MEn) which can handle n multiplex links (LE1, . . . LEn). The terminal modules are formed into groups in which the traffic of a faulty module is distributed among the other terminal modules of the group and forwarded over an auxiliary incoming line (L9, L10, L11, L12) of each terminal module by an input switch (5, 6, 7, 8) associated with each terminal module. An output switch (9, 10, 11, 12) associated with each terminal module and linked to the auxiliary outgoing line (13, 14, 15, 16) of the other modules collects the distributed traffic.