Abstract: A cellular mobile telephone system which can be used on board a vehicle enables conventional mobile telephones to be used on board an aircraft, for example. It includes a first transceiver on board the vehicle and connected to an antenna on the outside of the aircraft to set up an external radio link with a terrestrial mobile telephone network via a satellite. It further includes a second transceiver having an antenna inside the aircraft and connected to a base station controller. The second station and the base station controller have functions similar to those of a base station system in a conventional mobile telephone network, for example a GSM network. The base station controller is connected to the first transceiver. To prevent long signaling link set-up times, the base station controller includes software for setting up a signaling link between the aircraft and the terrestrial mobile telephone network in advance, as soon as at least one mobile telephone is switched on.

Abstract: A system for providing a mobile telephone service on board a vehicle is connected to a public land mobile network via a satellite and can set up at least one transport connection between the vehicle and the public land mobile network before receiving a call request and then use the transport connection for a call as soon as a request to set up a call is received.

Abstract: A dual-mode public and private telephone system is provided in which a switch-over switch makes it possible to go over from a mode in which a mobile telephone is used with public base stations to a mode in which it is used with a private base station. Provision is made such that putting the mobile telephone set on a stand of the private base station causes location transmission by the mobile telephone set to cease. As soon as the mobile telephone set is lifted off from its support, this causes an opposite command to be transmitted, whose effect is to cause the location transmission to be resumed.

Abstract: A cellular mobile telephone system which can be used on board a vehicle enables conventional mobile telephones to be used on board an aircraft, for example. It includes a first transceiver on board the vehicle and connected to an antenna on the outside of the aircraft to set up an external radio link with a terrestrial mobile telephone network via a satellite. It further includes a second transceiver having an antenna inside the aircraft and connected to a base station controller. The second station and the base station controller have functions similar to those of a base station system in a conventional mobile telephone network, for example a GSM network. The base station controller is connected to the first transceiver. To prevent long signaling link set-up times, the base station controller includes software for setting up a signaling link between the aircraft and the terrestrial mobile telephone network in advance, as soon as at least one mobile telephone is switched on.

Abstract: A multimode radio communication terminal includes a tunable source of transmit and/or receive local oscillator signals for transmitting and/or receiving channels of different frequency bands in at least two radio communication systems. The terminal includes, downstream of the tunable source, a switchable frequency changer implementing a fixed frequency change and selectively insertable so that, the source responding directly to the requirements of one radio communication system, insertion of the frequency changer renders it capable of responding to the requirements of another radio communication system using different frequency bands. This is achieved by virtue of a particular change to the frequency produced by the tunable source, effected by the frequency changer.

Abstract: In a method and a device for correcting a frequency offset between a receive signal and a reference signal, the receive signal, being fed to a frequency converter which also receives a conversion signal in order to produce a transposed signal, the conversion signal is produced by a local oscillator in response to a control signal. The device initializes the control signal according to the reference signal. An estimator receives the transposed signal and the control signal and produces repetitively an estimate of the frequency offset comprising the sum of a correction value and an adjustment value respectively greater than and less than a predetermined correction threshold. The control signal is modified in response to the correction value. The transposed signal is connected using at least one of the successive estimates.

Abstract: A portable mobile radio transceiver for direct communication with a radio relay on a satellite comprises a casing with a microphone and an earpiece and an antenna mounted on the casing. The main direction of radiation of the antenna is substantially vertical when the casing is in a position of use in which it is held in the hand near the head of the user.

Abstract: A dual mode portable digital radio transceiver for communicating via a terrestrial network (first mode) and via a satellite network (second mode) synthesizes a modulation first frequency for modulation of signals transmitted in both modes and a conversion second frequency for demodulation of signals received in the two modes. It divides the conversion second frequency supplying a conversion third frequency for demodulation of signals received in one of the modes using a signal receive frequency band far away from the other frequency bands used. It is therefore possible, using a single synthesized pure carrier, to carry out direct conversion in a first mode and intermediate frequency conversion followed by the same direct conversion in the second mode.

Abstract: A device and a method for the transmission or storage of data optimizing the use of the pass-band. Also, a method for transmission by phase modulation. In order to obtain high data throughput rates, the synchronization of a transmission clock with the reception clocks is used. This synchronization is gotten, for example, by transmission of a pseudo-random code and by the convolution or correlation of the received signals with the pseudo-random code. The invention also enables the elimination of multiple echoes by computation. The invention can be applied chiefly to the transmission of radio programs, television broadcasts or digital data.

Abstract: This radar receiver, in particular for a radar having an antenna with beam forming through computation, comprises essentially means for matched filtering having a bandwidth B, means for amplitude and phase detection, and means for analog-to-digital conversion, and is such that said means for analog-to-digital conversion work on the intermediate-frequency signals, at a frequency much higher than said intermediate frequency. The receiver can be fully constructed in gallium arsenide technology.

Abstract: A digital filter having parallel paths with a plurality of transverse filters in the paths. The period of treating the digital information of N connections at the output of a circuit for calculating the discrete Fourier transform on 2N points. The output of the transverse filter is fed to a circuit for calculating the inverse Fourier transform. These two circuits permit the transverse filters to function in each path with a data period of N. The filter will find particular application in convolvers, courolaters, and for circuits for the compression of digital pulses. The filter lends itself to application, particularly in radar, sonar, telecommunications, and in sound and imaging systems.

Abstract: A method and a device for reducing the power of jamming signals received by the secondary lobes of the main antenna AP of a radar transmitting at a random frequency f.sub.E (n), with which is associated a number of secondary antennas ASl, . . . ASN. The signals used for the calculation in circuit (10) of the weighting coefficients (Wl to WN) to be applied to obtain a signal resulting from the weighted linear combination of the secondary signals Dl, . . . DN to be subtracted from the signal Do in the main channel (VPD) relative to the transmission frequency f.sub.E (N+1) are those (V.sub.0, V.sub.1, . . . V.sub.N) processed in the main and secondary auxiliary channels (VPA, AsAl, . . . ASAN) relative to the transmission frequency f.sub.E (n+1) of the next recurrence train during the period of radar reception of the recurrence train corresponding to the transmission frequency f.sub.E (n) for the jammed range slots selected by circuit (15).

Abstract: An apparatus and method for reducing the power of active jamming signals received by the sidelobes of a radar antenna. A known method includes providing a radar with a main antenna and N auxiliary antennas, each antenna being associated with a corresponding processing channel. The signals received by the N antennas are each given a weighting coefficient corresponding to jamming on that channel. The N signals are then combined to form a weighted linear combination which is subtracted from the main channel signal to provide a signal with reduced jamming. The present invention provides apparatus and method for reducing clutter signals (such as fixed echoes and thermal noise) from each of the signals received in the N channels, thus producing very accurate weighting coefficients thereby allowing jamming power to be further reduced.

Abstract: A system for connection by means of optical fibers for the bidirectional exchange of data between a fixed central unit and peripheral units integral with a frame driven with a rotary movement, this system comprising radiating energy emitting and receiving means situated in the fixed part, coupled by optical fibers forming unidirectional data exchange paths to a single mixing fiber, itself coupled to optical fibers forming bidirectional data exchange paths coupled to radiating energy emitting and detecting means associated with the peripheral units integral with the mobile frame. Furthermore, the mixing fiber is split into two parts coupled together by a rotary optical joint.