Abstract: Efficiency of a digital link, e.g., a microwave link, is improved by coding numeric signals for transmission so as to transmit selected sequences, in terms of peak power of a filtered signal, for transmission through the link. The most favorable numeric sequences may be encoded by baseband numeric coding.

Abstract: The invention relates to a baseband signal combiner and to a sampler typically used in radio relay systems and also in generic communication systems. In order to avoid temporary failures in the free space links, space and/or frequency diversity techniques are used, which consist in the use of two suitably spaced receive antennas or of two transmission frequencies. By suitably combining the signals thus received, the failures in radio links can be redued. The invention provides the use of a particular algorithm of the type CMA (Constant Modulus Algorithm) which, being independent of the combined signal phase, does not interact with the carrier recovery circuits. Moreover, by also applying the same algorithm to the sampler, the cooperation of the two circuits for the optimization of the output signal is obtained.

Abstract: The invention relates to a method of reducing the peak power of a signal at the output of the transmit filter of a digital link, e.g. a microwave link. The invention is characterized by the use of a coding in transmission and a decoding in reception, adapted to reduce the peak power of the filtered signal. In the disclosed embodiment, not intended to be limiting, the encoder and the decoder can be realized through simple maps insertable in the baseband part of the system.

Abstract: The present invention concerns a method and a system for demodulating mutually interfering signals according to a suitable synchronism bond between said signals. With such a system a complete decoupling of the demodulators of said signals is obtained. The system is characterized in that on each polarization there is at least a pair of demodulators, a first pair operate a baseband conversion of both signal H and V using the carrier recovery circuit driven by data of one of the two signals (e.g. V) and a second pair operate still a baseband conversion of both signals H and V but using said carrier recovery circuit now driven by data of the other signal (e.g. H).

Abstract: A method of estimating the carrier frequency of a numeric signal, in which two estimates of the carrier phase are carried out in successive instants of time and the estimated carrier frequency is obtained from the comparison of the above two estimates. The invention also concerns a device for implementing the method, the device including a circuit for estimating the phase of the signal at successive instants in time, a circuit for storing the estimates, and a circuit for comparing the estimates. In a preferred embodiment, both the phase estimator and the comparison circuit are implemented by multipliers and adders.