Alcatel Espace

Societe Anonyme Dite : Alcatel Espace

Compagnie Europeenne De Teletransmission (c.e.t.t.)

Sylvain Fontanes

Andre Marguinaud

Thierry Quignon

Brigitte Romann

Patrice Birot

Daniel Forster

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.

Method of demodulating digitally modulated signals, and apparatus

A frame (T) is sub-divided into identical time slots (61, 62, . . . , 6N) of fixed duration, each of which is capable of containing at least one lowest data rate telephone channel. These time slots are assigned on demand so that a new call is spread over one or more bursts (81, 82, 83, 84) which are located in available ones of said time slots, or else in space which may be left available in time slots which are already partially occupied by other, low data rate calls.

Method and system for time division multiple access satellite

For multiplexing 6 binary channels for example, two transcoders are respectively fed by the groups of input channels A, B, C and D, E, F in each of which is inserted a locking and identification word. Two three-channel frames in intermediate ternary form are thus obtained. Conversion into definitive ternary code (moment +, O, -) takes place at the same time as the interlacing, moment by moment, of the two three-channel frames. The demultiplexer groups the moments pertaining to one and the same three-channel frame for transcoding. The system allows high speed multiplexing.

High speed multiplexer and demultiplexer for pulse code channels

In a modulator of the type including a memory in which coded binary words representative of samples of a cycle of a sinusoidal signal are stored, which coded words are used to synthesize the modulated signal, the bits of each input digital signal S.sub.i are grouped in groups of P.sub.i bits (P.sub.i .gtoreq.1) and the sampling of the groups is so performed that several samples of each group appear in the multiplexed signal resulting from the sampling. Each sample of each group causes the reading of a coded word. This process gives a wide range of possibilities as concerns the transmission speeds of the input channels and the choice of the carrier frequency and of the number of modulation levels for each modulated signal.

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Chatou, France

Sylvain Fontanes