Abstract: Method and device for the equalization of a signal received by a receiver, said signal comprising at least one known data sequence (or probe) and a data block located between a first Probe n-1 and a second probe Probe n. The method comprises a step of estimation of the phase rotation &thgr; of the signal received between the first probe Probe n−1 positioned before the data block to be demodulated and the second probe Probe n positioned after the data block to be demodulated.

Abstract: Method and system adapted to modifying an audio signal or speech signal comprising a step in which the frequency spectrum S(k) of the signal is converted by the application of a non-linear function. The method comprises at least the following steps: firstly, determining the signal level A(k), B(k) associated with a frequency k by taking account of different levels a(k), b(k) of the signal for the frequency k concerned and/or the neighboring frequencies (step 2a, step 8a); secondly, applying the non-linear function to said level A(k), B(k).

Abstract: Disclosed is a method and device that use a digital type modem to transmit analog signals. The modem is of the OFDM, COFDM or single-carrier type. Application to the transmission of a speech or audio signal in total security.

Abstract: A process for transmitting mixed analog and digital signals. A composite signal is transmitted whose frequency spectrum is composed of a first analog spectrum representative of the amplitude of single-sideband modulation and of a second spectrum composed of multi-subcarriers. The two spectra occupy two disjoint frequency bands. The device may be used for simultaneous broadcast of the same program or its reception by analog or digital receivers.

Abstract: Disclosed is a system and method to provide continuity of service in a radio broadcasting system comprising at least one modem using the COFDM technique, comprising the transmission of N time-frequency cells modulated independently of one another.

Abstract: A process for the vector quantization of low bit rate vocoders, including determining a coding region by surrounding with an envelope a scatter of points of an autocorrelation matrix of reflection coefficients of a filter configured to model a vocal tract, wherein the envelope has a shape selected from the group consisting of a hyperellipsoid shape and a pyramidal shape, the envelope being centered at the barycenter of the scatter of points; determining principal axes of the volume of points inside the envelope; projecting area coefficients of the autocorrelation matrix onto the principal axes; partitioning the interior volume of the envelope into elementary volumes; and coding partition coefficients resulting from partitioning the interior volume on the basis of coordinates of said partition coefficients in a space defined by the principal axes of the volume of the points inside the envelope, while allocating as code values only values corresponding to locations of the elementary volumes in which said partit

Abstract: A quantization process proposes a low data rate for predictor filters of a vocoder with a speech signal broken down into packets having a predetermined number L of frames of constant duration and a weight allocated to each frame according to the average strength of the speech signal in the respective frame. The process involves allocating a predictor filter for each frame and determining the possible configurations for predictor filters having the same number of coefficients and the possible configuration for which the coefficients of a current frame predictor filter are interpolated from the predictor filter coefficients from neighboring frames. Subsequently, a deterministic error is calculated by measuring the distances between the filters in order to form a first stack with a predetermined number of configurations which give the lowest errors.

Abstract: The disclosed method consists of: the cutting up, after sampling, of the speech signal into frames of a determined duration; the carrying out a first self-adaptive filtering of the sampled signal (Sn) obtained in each frame to limit the influence of the first formant; the carrying out a second filtering to keep only a minimum of harmonics of the fundamental frequency; and the comparing of the signal obtained with two adaptive thresholds SfMin(n) and SfMax(n), respectively positive and negative and changing as a function of time according to a predetermined relationship so as to choose only the signal portions that are respectively above or below the two thresholds.

Abstract: A method of breaking up a vocal signal into binary frames of a predetermined duration. The frames are grouped together in packets of successive frames by associating a predictive filter with each frame of a packet. Furthermore, the coefficients of each predictive filter are quantified by taking into account the stable or non-stable configuration of the vocal signal.

Abstract: An algebraic coder-decoder for Reed Solomon and BCH block codes is provided, namely a coprocessor of standard microprocessors specialized for algebraic processing in Galois bodies. This processor includes a clock generator which sets the rhythm of the circuit through a cycle clock and a subcycle clock, a control circuit which integrates an automatic loop system and a cycle stealing device, an arithmetic operator for carrying out simple operations on unsigned numbers representing the variables and the parameters of the algorithms a Galois operator for effecting the elementary polynomial operations in the five Galois bodies and storing the data exchanged with the host processor, an interface circuit which integrates a data exchange managament automation, a data bus, an instruction and the connections required for the control signals which connect the four blocks of the device together.

Abstract: The polynomial operator in the Galois field of the invention is organized at three levels:a multiplexer level to select and transmit the operands to be used for the successive stage of the calculation to a second level;a so-called pipeline level comprising 3 flip-flop registers to memorize the operands selected at the first level;a third level for calculation, comprising a multiplier-adder which has its inputs X, Y and Z connected to the outputs of the registers, and which gives the coefficients of the resultant polynomials in the Galois field while always performing the same calculation by repetition of the same control instruction. This operator can be applied to digital telecommunications for the encoding and decoding of BCH or RS (REED SOLOMON) error-correcting codes, and can be used to make an integrated processor capable of processing digital data in the form of octets.