Abstract: A method for reducing the peak-to-average power ratio (PAR) of a multicarrier signal in transmitter/receiver systems. The method comprises the steps of: providing, in transmission, a digital signal to be transmitted; and subjecting such a signal to be transmitted to a Fourier transform in order to obtain a modulated signal. It is characterized by the steps of generating an anti-peak signal; summing said anti-peak signal with said modulated signal; and transmitting the sum signal. The invention provides a transmitter and a receiver for implementing the method. Through the use of the invention, the PAR is reduced as compared with the known techniques.

Abstract: A receiver for an optical transmission system in air is described. The receiver includes at least one receiving lens for focusing a beam received from a remote transmitter and a detector. The receiver is characterised in that it includes a portion or section of tapered optical fibre inserted basically into the focal plane of the at least one receiving lens. A method for increasing the gathering area in a receiver for an optical transmission system in air is also described.

Abstract: Method for receiving/trasmitting an optical signal through the air, the method comprising the steps of: providing a first free space optics apparatus; providing a second free space optics apparatus, the first and second apparatuses being spaced by a certain distance; at the first apparatus, transmitting an optical signal through the air at a bit-rate; receiving, at the second apparatus, said optical signal transmitted through the air by the first apparatus. The method being characterized by further comprising the steps of: measuring the power level of the received signal; and operating a switch for accomodating the bit-rate in order to change the fading margin in the apparatus. A lower bit-rate being used when the level of the received power is low and/or in rather bad weather conditions.

Abstract: A method and/or system for stabilizing the operation of fractionally spaced equalizers has a number of taps (P), associated with which are respective equalization coefficients (c−L, . . . , cL), used in digital signal receivers, wherein the equalization coefficients (c−L, . . . , cL) are updatable to an algorithm (1) based on the minimization of a proper cost function (J) and stabilized for operation through a proper a modification (I) involving calculation of a plurality of values (Ii) to be considered in updating the equalization coefficients (c−L, . . . , cL). According to the invention, these values (Ii) are calculated in only one circuit (COMP) and serially transmitted to the fractionally spaced equalizer (FSE).

Abstract: A method for reducing the peak-to-average power ratio (PAR) of a multicarrier signal in transmitter/receiver systems. The method comprises the steps of: providing, in transmission, a digital signal to be transmitted; and subjecting such a signal to be transmitted to a Fourier transform in order to obtain a modulated signal. It is characterized by the steps of generating an anti-peak signal; summing said anti-peak signal with said modulated signal; and transmitting the sum signal. The invention provides a transmitter and a receiver for implementing the method. Through the use of the invention, the PAR is reduced as compared with the known techniques.

Abstract: A method is described for estimating at least the inverse amplitude characteristic in a high-power amplifier for transmission systems, wherein the estimation is carried out by estimation means receiving the signal samples, possibly demodulated, as inputs present at the input and at the output of the amplifier.