Abstract: The invention relates notably to a method for transmitting frames on a radio communication channel (RCC), the frames comprising a succession of bursts (B1, . . . , Bn) modulated with at least two different modulation schemes (M1, M2, M3) having different modulation efficiencies, each modulation scheme (M1, M2, M3) having a corresponding average transmitted power. The method according to the invention comprises the steps of: mapping information to be transmitted to modulation symbols using one of the modulation schemes (M1, M2, M3); filtering the modulation symbols using a digital transmission filter with a set of coefficients, the set being chosen from at least two sets of coefficients depending on the modulation scheme (M1, M2, M3) used at the mapping step, the product of the average transmitted power and the gain of the digital transmission filter being smaller than a predefined value for all modulation schemes (M1, M2, M3).

Abstract: The invention relates notably to a method for transmitting frames on a radio communication channel (RCC), the frames comprising a succession of bursts (B1, . . . , Bn) modulated with at least two different modulation schemes (M1, M2, M3) having different modulation efficiencies, each modulation scheme (M1, M2, M3) having a corresponding average transmitted power.

Abstract: An estimator for estimating an operating defect in a quadrature modulator, including two mixers to which respective carrier signals are applied, and to which respective modulating signals are also applied. The output signals from the mixers are applied to a summing circuit so as to constitute a modulated signal. The estimator includes detection circuitry for detecting the instantaneous power of said modulated signal; multiplication circuitry for multiplying the detected instantaneous power by at least one of the modulating signals; and integration circuitry for integrating the result of the multiplication and for supplying a signal indicative of the operating defect of the modulator. The modulator is particularly applicable to removing the residual amount of the carrier signals that remains in the modulated signal, and to correcting the quadrature between the signals output by the mixers.

Abstract: A system for receiving a complex modulation digital signal using a temporal equaliser including an estimator supplying correction parameters. This system includes: at least one peripheral control loop, the estimator of which uses at least one of said correction parameters, the peripheral control loop having an operating range separate from that of the temporal equalizer; and a temporal discriminator detecting inactive areas of the estimator of each peripheral control loop to enable operation of the temporal equalizer in such a way as to prevent interaction between the temporal equalizer and the peripheral control loop. The peripheral control loop can be a Mueller and Muller-type pointing estimator and/or a Leclert and Vandamme-type carrier recovery device.

Abstract: A method of recovering the carrier for modulation having a large number of states, the method being wherein the demodulated constellation is brought to the monotonic range of a conventional estimator, with sufficient accuracy to enable autonomous operation on this new criterion. The invention also provides apparatus for implementing the method. The invention is particularly applicable to digital ratio beam transmission.