Alcatel Espace

Societe Anonyme Dite : Alcatel Espace

Alcatel

Alcatel N.v.

Alcatel Alsthom Compagnie Generale D'electricite

Andre Marguinaud

Sylvain Fontanes

Thierry Quignon

Brigitte Romann

Patrice Birot

Jean-Didier Gayrard

Eric Belis

Jan Mennekens

Jean Broyer

Nadia Dezelak

Daniel Rousset

Geert Alfons Sonck

Denis Broux

Philippe Richard Dosiere

Dietmar W Schill

The invention concerns a communications system including at least one transmit antenna near at least one receive antenna, transmission producing signals in the receive frequency band. The system includes a transmit neutralizing circuit for supplying a correction signal for eliminating only interfering signals whose frequency is in the receive signal frequency band. The transmit neutralizing circuit is on the input side of an amplifier and comprises means for evaluating, in the wanted receive frequency band, a limited number of parameters of the power amplifier feeding the transmit antenna, this evaluation of parameters being effected on the basis of the input and output signals of the amplifier. The circuit also evaluates the signals causing the interference prior to the input of the amplifier; this evaluation of the interfering signals is based on the calculated parameters and the signal at the input of the amplifier. Application to transmission systems on ships or spacecraft.

Communications system including closely spaced transmit and receive

A method of synthesizing a finite impulse response digital filter includes a phase of calculating the impulse response g(t) of an analog filter the transfer function of which is defined by a predetermined bandwidth B, shape factor SF and out-band attenuation level A. The coefficients of the digital filter are extracted by sampling the resulting impulse response. The calculation phase consists in expanding the impulse response into an integer number M of Hermite functions predetermined in accordance with the shape factor SF. The coefficient extraction phase includes sampling of the expanded impulse response after the calculation phase in a time window the duration of which is dependent on the out-band attenuation level A using a sampling period At that is dependent on the bandwidth B.

Method of synthesizing a finite impulse response digital filter and

A method for frame synchronization including the detection of an n-bit pattern with predetermined characteristics in a bitstream is described. The subject method includes the steps of extracting a first set of m bits, with m being smaller than or equal to n, from a first position in said bitstream, deriving from said first set an address of a location in a first memory, deriving from the contents of said location in said first memory at least one second position in said bitstream and at least one second set of bits to be extracted therefrom until said n-bit pattern is detected in said bitstream. An apparatus for performing the subject method is additionally described.

Frame synchronization method

A high-throughput filtering method and corresponding apparatus in which each output sample sn is determined by weighting N input samples xi by multiplying the input samples by N coefficients, where the N coefficients are each decomposed into a set of coordinates, each coordinate corresponding to P bits of the coefficient. Essentially, input samples are multiplied by the coordinates of each of the coefficients in a pre-processing operation where the output signals corresponding to the resulting products for a coefficient are added in an adding block. A plurality of adding blocks are provided corresponding respectively to the coefficients such that each block includes the summation result of the products for a corresponding coefficient. The summation result from a previous adding block is added to the summation result of a current block, and the result of this addition is supplied to the next adding block. The output signal is obtained in this manner.

High-throughput digital filtering method and apparatus for performing

An analytical digitizer for signal processing includes a sampler and an analog/digital converter. A first calculating device supplies a first component of the signal made up of a sequence of digital values. Each value is calculated by adding 2h+2 value supplied by the converter weighted with respective non-null integer coefficients a.sub.0, . . . , a.sub.h, a.sub.h, . . . , a.sub.0. A second calculating device supplies a second component of the signal, in phase quadrature to the first, and made up of a sequence of digital values y(t). Each of these values is calculated by adding 2h+2 values supplied by the converter weighted with respective non-null integer coefficients b.sub.0, . . . , b.sub.h-1, -b.sub.h-1, . . . , -b.sub.0. The number and the value of the coefficients are determined by a rigorous method according to the center frequency and the bandwidth of the spectrum of the signal to be processed and according to a fixed limit value for the signal/noise ratio. The device finds an application in radio surveillance receivers.

Method of calculating weighting coefficients for an analytical digitizer

A method of digitally evaluating the frequency and the phase of signals in the form of digitized samples, the method being wherein it comprises in succession: a stage during which numbers corresponding to the samples of the signals to be analyzed are processed in order to convert them into the form of an analytic signal whose real portion coincides with said signal to be analyzed; and, in parallel therewith: a stage of estimating the parameters to be analyzed which is performed in an overall manner on the basis of estimators and of selection criteria by working on the phase of the signal without using any operator of the Fourrier transform type of any hypothesis test either separately or simultaneously; and a stage of estimating the differences between the real signal as taken in this way and the signal obtained from the estimated parameters, thereby making it possible to deliver data in digital form relating to the quality of the analyzed signal and to the reliability of the estimated values. The invention is applicable, in particular, to microwaves.

Method of digitally evaluating the frequency and the phase of signals,

A method of digitally evaluating the frequency and the phase of signals in the form of digitized samples, the method being wherein it comprises in succession:

A signal may be demodulated without using any analog components by using a digital processor. A digitizer delivers the amplitude of the signal to be demodulated at a sampling rate. The signal is acquired from the digitizer and stored in a common memory. The amplitude samples are converted to phase samples. Symbol rate phase hypotheses are generated for splitting the time signal into slices. The carrier phase for one symbol is then calculated for each symbol rate phase hypothesis so that the carrier phase can be estimated over a plurality of (S) symbols. The symbol phase is compared to the carrier phase so that the demodulated signal may be extracted and so that the quality of the demodulation may be estimated.

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Palaiseau, France

Andre Marguinaud