Dassault Electronique

Thomas Csf Detexis

Dessault Electronique

Thierry Potier

Michel Geesen

Daniel Wozniak

Patrick Souty

Radio transmission of chronometric information. A device comprising an antenna (A, A) to which there are coupled on one hand a generator (G, G) generating a signal to be sent (e, e) and a reception processing circuit (C, C), capable of processing a received signal (r, e) where the signals exchanged have the same carrier frequency. Separate time segments are generated with successive random positions. Transmission is enabled only during these time segments, whilst reception is enabled only outside these segments, making it possible to use the time markers of the signals without any effect of recurrent masking of the reception signal by the transmission signal.

Device for exchanging radio signals provided with time markers for synchronizing clocks

A clock generates clock pulses defining a plurality of clock cycles. A circuit is connected to receive the clock pulses and measure a primary time of occurrence of an event with respect to a clock cycle. Logic circuits are provided to generate a timing pulse representing a time interval between the event and a clock pulse of the subsequent clock cycle. The timing pulse begins at the time of the event and ends on the occurrence of a subsequent clock pulse. A filter circuit receives the timing pulse and generates in response thereto a signal having an amplitude representing the duration of the timing pulse. The amplitude is measured to determine the width of the timing pulse thereby identifying the occurrence of the event with respect to a subsequently occurring clock pulse.

Apparatus and method for accurately measuring the time of an event

A frequency synthesizer device which comprises a combination of: an oscillator, a phase comparator, a frequency generator having an input receiving the reference frequency of value OF and N outputs, with N being a whole number between 1 and N, each output being designed to deliver a frequency having a value equal to 2.sup.N FO, a phase-locked loop consisting of N links connected in series between the output of the oscillator and the first input of the comparator, each link comprising a mixer having a first input connected to one of the outputs of the frequency generator, a second input and an output, the second input of the current mixer being connected to the output of the preceding mixer and the second input of the mixer being connected to the output of the oscillator.

Frequency synthesizer having a frequency generator with N multipliers

A relay satellite receives, from stations on the ground, modulated high-frequency signals situated in two different frequency bands. One of the modulations is narrow band and the other broad band. The satellite retransmits a multiplexed signal resulting from the phase modulation, of a sub-carrier consisting of the signal modulated by the narrow band modulation. The phase modulation is performed using signals drawn from the signals that carry the broad-band modulation. The user stations receive this multiplexed signal and extract therefrom, by filtering, the narrow band modulated sub-carrier, which can be used for phase-demodulating the multiplexed signal in order to recover signals which carry the broad-band modulation.

Method and devices for transmitting data, particularly by satellite

The invention concerns a feedback control loop comprising a mixer comprising a first input receiving an electromagnetic signal, and a second input receiving a first local signal; an intermediate frequency line mounted between the output of the mixer and the input of a phase comparator which receives on a second input a second local signal and has an output; and a feedback line connected between this output and the second input of the input mixer, and comprising a loop filter controlling a variable oscillator for providing the said first local signal as well as a second variable oscillator for providing the second local signal. The loop filter comprises (i) a proportional section mounted between the output and the control input of a second variable oscillator; (ii) an integral variable section mounted between the output of the proportional section and the control input of the first variable oscillator; and controller capable of progressively changing the parameters of the proportional and integral sections so as to progressively reduce the bandwidth of the phase control system and to increase the filtering of the noise and of the interference signals superposed on to the electromagnetic signal.

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Maurepas, France

Thierry Potier