Abstract: An estimator for estimating an operating defect in a quadrature modulator, including two mixers to which respective carrier signals are applied, and to which respective modulating signals are also applied. The output signals from the mixers are applied to a summing circuit so as to constitute a modulated signal. The estimator includes detection circuitry for detecting the instantaneous power of said modulated signal; multiplication circuitry for multiplying the detected instantaneous power by at least one of the modulating signals; and integration circuitry for integrating the result of the multiplication and for supplying a signal indicative of the operating defect of the modulator. The modulator is particularly applicable to removing the residual amount of the carrier signals that remains in the modulated signal, and to correcting the quadrature between the signals output by the mixers.

Abstract: A method of controlling a digital carrier recovery apparatus designed to be integrated in a demodulation stage of a receiver for receiving a digital signal. The demodulation stage includes a carrier recovery detection apparatus. The carrier recovery detection apparatus includes a loop filter including a summing circuit followed by a bistable circuit operating in time with the symbol time, and a switching device disposed between the summing circuit and the bistable circuit. The switching device is driven to alternately apply to the bistable circuit a control word, whose variation between two successive applications to the bistable circuit is less than the acquisition band of the carrier recovery apparatus, and the output signal of the summing circuit. By alternately applying the control word and the output signal, the acquisition band is displaced relative to the tracking range of the carrier recovery apparatus.

Abstract: In a convolutional coding and Viterbi decoding system transparent to phase skips of .pi. and .pi./2 with applications in TDMA transmission, the transmitter 3 includes a demultiplexer receiving a digital bit stream and operating at the bit timing rate, a QPSK differential coder receiving the demultiplexed bit streams and supplying two coded bit streams, two convolutional coders each supplying one code word, and two multiplexers each receiving one code word from a respective convolutional coder and supplying one component of a symbol to be transmitted. The receiver generates two received symbol components which are applied to two demultiplexers each supplying one code word. Each bit of a code word is applied to a single Viterbi decoder. A QPSK type differential decoder supplies two decoded bit streams which are then multiplexed.

Abstract: An electronic circuit is implemented on a substrate on an electrically conductive bottom plate fixed into an electromagnetic shield box. A coaxial socket is fixed to an outside wall of the shield box, the core of the socket being inserted in a hole in the wall in order to be connected to the electronic circuit. The socket has a grounding surface facing the wall. The grounding contact between the socket and the bottom plate is made by way of an electrically conductive ring coaxial with the core, insulated from the core and simultaneously in electrical contact with the grounding surface of the socket and the bottom plate when the socket is fixed to the wall of the box.

Abstract: A device for recovering the carrier of a TDMA signal supplies the complex envelope of this signal on a real channel and an imaginary channel. Circuitry for offsetting the constellation of the complex envelope by .pi./4 supply a complex signal on a main channel and on an auxiliary channel. An energy detector arrangement controls a multiplexer so that it supplies to a correlator whichever of the real or imaginary channels conveys the greater energy. The correlator calculates the correlation level between the multiplexer output signal and a reference singular word. An arrangement for comparing the correlation level with a threshold value indicates detection of the singular word in the signal on the channel applied to the correlator.

Abstract: A spread spectrum digital transmission system using low-frequency pseudorandom encoding of desired information, and a spectrum spreading and compression method used in such a system. In a transmitter in the system, each block of a digital signal to be transmitted is combined with a sample obtained from a low-frequency pseudorandom generator. The resulting various combinations are converted into orthogonal or quasi-orthogonal sequences which are modulated and transmitted to a receiver. The receiver demodulates the signal received and combines each sequence with a sample identical to that used for the low-frequency coding at the transmitter to recover the various blocks of the transmitted signal. Hence, low frequency spectrum spreading of a signal to be transmitted is achieved.

Abstract: A system of communicating by a satellite link between telephone switching centers via traffic stations includes a management center and an originating switching center. The management center includes a device for analyzing call requests formulated by the switching centers. An originating switching center formulates a call request via an originating traffic station connected to the switching center and responds to the call requests by assigning a resource of a satellite and a resource of a terminating traffic station connected to a terminating switching center with which a call is to be set up in order to provide communication between the originating and terminating traffic stations. The originating traffic station includes a device for routing call requests formulated by the originating switching center on frames divided into time slots, with each time slot corresponding to a predetermined terminating traffic station.

Abstract: A system for receiving a complex modulation digital signal using a temporal equaliser including an estimator supplying correction parameters. This system includes: at least one peripheral control loop, the estimator of which uses at least one of said correction parameters, the peripheral control loop having an operating range separate from that of the temporal equalizer; and a temporal discriminator detecting inactive areas of the estimator of each peripheral control loop to enable operation of the temporal equalizer in such a way as to prevent interaction between the temporal equalizer and the peripheral control loop. The peripheral control loop can be a Mueller and Muller-type pointing estimator and/or a Leclert and Vandamme-type carrier recovery device.

Abstract: System for dissipating heat energy generated by an electronic component and sealed enclosure used in a system of this kind.The system for dissipating heat of the invention is of the type comprising a sealed metal enclosure (21) the interior volume of which contains a fluid (22), said component (11) being fixed to the outside wall of said enclosure (21) and connected to a heat dissipator (12) by said enclosure (21) and is characterized in that the phase change temperature of the fluid (22) at atmospheric pressure is less than a given maximum ambient temperature and in that said enclosure (21) also contains a volume of gas (23) different from the fluid (22) so that variation in the ambient temperature causes a variation in the pressure inside the enclosure (21) which modifies the phase change temperature of the fluid (22).

Abstract: A device for synchronizing the phase of each packet of a phase modulated digital signal comprises a correction module controlled by information supplied successively by two separate calculator circuits. The phase synchronization device can be integrated into the demodulator stage of a receiver for digital signals phase modulated with at least two phase states, this signal being transmitted by successive packets. The device comprises a corrector module for rotating the constellation of phase states of the received signal according to an indication representative of the angular offset of this constellation.

Abstract: In a method of detecting false-locking the trains of clock signals corresponding to the two phase offset initially modulated trains of signals, the phase offset between said trains of clock signals is monitored, and false-locking is detected when the phase offset changes signal. Also, a method of demodulation implements this method of detecting false-locking. Also, a device for implementing the method of detecting false-locking contains a flip-flop in series with a monostable.

Abstract: A device for demodulating a signal modulated on two axes in phase quadrature using a .pi./4-QPSK type digital modulation technique employing alternately two phase-shifted constellations. The device includes: a voltage-controlled oscillator (28) supplying a local signal substantially at the carrier frequency; a demodulator means using the local signal and supplying, after filtering (30, 31), the phase component P and quadrature component Q of the demodulated received signal; a phase controller (32) producing a control signal (39) for controlling the oscillator (28) and including a phase estimator (33) producing a phase estimation signal E (35) involved in control of the oscillator (28), the phase estimation signal being derived from the phase component P and quadrature component Q of the demodulated received signal.

Abstract: In a method of allocating carrier frequencies for transmission within a transmission network, such as a tactical network, the set of carrier frequencies constituting the available frequency resource for the network is broken down into batches of unequal size. At the time it enters the network, as indicated by a request for allocation of a frequency for a link between it and another site (referred to as the first connection for the site), and previous to such allocation, any site of the network is allocated one of two complementary states so as to obtain complementary states for the site in question and for its first connection site. These states are retained for subsequent links between the site in question and other sites of the network. For any link to be set up between two sites of the network, a frequency is allocated at random from the largest batch if the sites in question are in complementary states or from a smaller batch if the sites in question are in the identical state.

Abstract: The transmitter uses a synthesized oscillator (1A) whose reference (24) is provided by the clock (H) of the data (P, Q). The demodulation oscillator (13A) of the receiver is a synthesizer which is functionally identical to that (1A) of the transmitter, and its reference (23) is provided by the clock (H, 36) recovered from the received data.

Abstract: Agile microwave filter having at least two two-mode cavities with parallel axes and coupled by an iris. The input and output ports are irises in the back plate of the filter. The frequency response of the filter is therefore symmetrical. The plate and therefore the irises are interchangeable to increase the agility of the filter.

Abstract: A regenerator for regenerating received framed digital signals including justification bit includes an arrangement associating justification mechanisms with the operation of a fractionally spaced self-adaptive equalizer which is modified to accept instructions to rotate its coefficients. The regenerator is particularly suitable for microwave digital transmission. Jitter does not accumulate in the regenerator which may be implemented entirely in digital circuits.

Abstract: An interface for inserting equipments interconnected by a traffic telecommunication network into a management system for the equipments includes a management support telecommunication network. The system also includes, for each equipment and integrated in one and the same physical entity, an interface with the management support network and an interface with the equipment.

Abstract: A dynamic management system for a set of traffic data transmission equipments connected by a traffic telecommunication network and operating together in variable configurations matched to the requirements of network users includes a management support telecommunication network having a plurality of nodes which are constituted by management data switching and access equipments associated with respective traffic data transmission equipments and assembled into a meshed network which is topologically independent of the traffic network and uses flooding mode broadcasting.

Abstract: A method and apparatus for coherent demodulation for phase shift keyed signals including:a phase estimation stage based on a sequence of reference symbols transmitted at the start of each block of data anda second order phase-locked loop stage.

Abstract: A method of detecting a disturbing signal for demodulating digital data, wherein, on the modulated signal transposed into baseband, the disturbing signal is detected by periodically inserting known signals by means of a fixed guard time delay ((R+I)T.sub.s) applied to the received signal prior to demodulation, and wherein said method includes: a step of estimating the square of the modulus of the cross-correlation of the received referenced signal and of the expected signal at a determined instant when the reference signal is assumed to be present; a step of estimating the square of the correlation of the received signal at the same instant, of multiplying by a coefficient which represents the square of the threshold for the estimated correlation coefficient, and of multiplying by the number of reference symbols used in a reference burst; and a step of comparing with each other the two quantities obtained simultaneously during the preceding two steps.