Abstract: A method for adaptively controlling bandwidth of a carrier recovery loop in radio transmission systems, wherein the phase error in a PLL is adjusted to a minimum level by means of a loop filter incorporated in said PLL. The phase noise value in the local oscillator is determined and the value of the additive white gaussian noise in the PLL is estimated. Next these values are applied in a predetermined mathematical relationship indicative of the phase error in said PLL in such a manner that the desired wavelength of the PLL can be determined by corresponding to a minimum value of the phase error.

Abstract: A method and apparatus is described for the automatic delay compensation in space diversity radio transmissions. The method includes the steps of: a) receiving a first analog signal and a second analog signal, a possible delay being between the first and second signals; b) sampling the first and the second analog signals to obtain a first digital signal and a second digital signal, respectively; c) sending the digital signals to respective equalizers, and the steps of d) digitally delaying one of the first digital signal and the second digital signal by a period equal to an integral multiple of the sampling period, and e) recoverying, at the equalization phase, the residual difference between the imposed delay and the actual one.

Abstract: Disclosed is a method for controlling the peak power of a filtered signal in a single carrier data transmission system. The method comprises the steps of receiving a digital sequence (13) from a data source; generating a new digital sequence (a(k)); shaping filtering (34) the new digital sequence (a(k)) and producing a filtered digital sequence (y(k)) Characterized in that the step of generating a new digital sequence (a(k)) comprises the steps of: encoding data by an algebraic error correcting code (28); and performing a bit modification (30) by deliberately adding errors in such a way that the peak power of the filter signal affected by the deliberately introduced errors is lower than the peak power of the signal unaffected by errors. Disclosed is also a circuit for performing the method.

Abstract: A method is provided for realizing, in a radio transmission system, a carrier synchronization and for cancelling one or more co-channel interfering signals from a received main signal, in which a synchronous down-conversion of the received main signal and of each of the interfering signal is performed to obtain respective intermediate frequency signals; and then a synchronous demodulation of the intermediate frequency signals so obtained is carried out.

Abstract: Described is a method for the clock-pulse selection in a baseband combiner of a space-diversity receiver. The method provides for driving the clock recovery circuit by means of the main signal, filtered and sampled, or by the diversity signal, filtered and sampled as well, and it is characterized by calculating the average power of the equalized main signal and the average power of the equalized diversity signal; and by driving the clock recovery circuit by means of the signal chosen according to a comparison between the average powers of the signals at the output of the equalizers. Advantageously, the invention provides for a hysteresis on the power comparison and guarantees a soft change with respect to the selection performed at the preceding time of processing.

Abstract: A method is described for managing and monitoring the performances in digital radio systems. The idea of the invention provides for identifying the type of distorting phenomenon that possibly affects the monitored radio channel; in this way it is also possible to univocally connect, apart from the cause of degrade, the system performances with one of the performance monitoring methods commonly usable. In practice, the invention utilizes two distinct thresholds, each specific to the related corrupting source, and above all it provides an effective technique for discriminating which of the two thresholds is to be compared with the measure of the quality chosen. In a first preferred embodiment of the invention, the type of distortion present in the channel is identified on the basis of the error autocorrelation test at the threshold decision circuit.

Abstract: A method for adaptively controlling bandwidth of a carrier recovery loop in radio transmission systems, wherein the phase error in a PLL is adjusted to a minimum level by means of a loop filter incorporated in said PLL. The phase noise value in the local oscillator is determined and the value of the additive white gaussian noise in the PLL is estimated. Next these values are applied in a predetermined mathematical relationship indicative of the phase error in said PLL in such a manner that the desired wavelength of the PLL can be determined by corresponding to a minimum value of the phase error.

Abstract: Disclosed is a method for controlling the peak power of a filtered signal in a single carrier data transmission system. The method comprises the steps of receiving a digital sequence (13) from a data source; generating a new digital sequence (a(k)); shaping filtering (34) the new digital sequence (a(k)) and producing a filtered digital sequence (y(k)) Characterized in that the step of generating a new digital sequence (a(k)) comprises the steps of: encoding data by an algebraic error correcting code (28); and performing a bit modification (30) by deliberately adding errors in such a way that the peak power of the filter signal affected by the deliberately introduced errors is lower than the peak power of the signal unaffected by errors. Disclosed is also a circuit for performing the method.

Abstract: It is described a method for realizing, in a radio transmission system, a carrier synchronization and for cancelling one or more co-channel interfering signals from a recived main signal, in which a synchronous down-conversion of the received main signal and of each of the interfering signal is performed to obtain respective intermediate frequency signals; and then a synchronous demodulation of the intermediate frequency signals so obtained is carried out.

Abstract: Described is a method for the clock-pulse selection in a baseband combiner of a space-diversity receiver. The method provides for driving the clock recovery circuit by means of the main signal, filtered and sampled, or by the diversity signal, filtered and sampled as well, and it is characterized by calculating the average power of the equalized main signal and the average power of the equalized diversity signal; and by driving the clock recovery circuit by means of the signal chosen according to a comparison between the average powers of the signals at the output of the equalizers. Advantageously, the invention provides for a hysteresis on the power comparison and guarantees a soft change with respect to the selection performed at the preceding time of processing.

Abstract: A method is described for managing and monitoring the performances in digital radio systems. The idea of the invention provides for identifying the type of distorting phenomenon that possibly affects the monitored radio channel; in this way it is also possible to univocally connect, apart from the cause of degrade, the system performances with one of the performance monitoring methods commonly usable. In practice, the invention utilizes two distinct thresholds, each specific to the related corrupting source, and above all it provides an effective technique for discriminating which of the two thresholds is to be compared with the measure of the quality chosen. In a first preferred embodiment of the invention, the type of distortion present in the channel is identified on the basis of the error autocorrelation test at the threshold decision circuit.

Abstract: A method and apparatus is described for the automatic delay compensation in space diversity radio transmissions. The method comprises the steps of: a) receiving a first analog signal and a second analog signal, a possible delay being between the first and second signals; b) sampling said first and said second analog signals to obtain a first digital signal and a second digital signal, respectively; c) sending said digital signals to respective equalizers, and the steps of d) digitally delaying one of the first digital signal and the second digital signal by a period equal to an integral multiple of the sampling period, and e) recoverying, at the equalization phase, the residual difference between the imposed delay and the actual one.

Abstract: A method and device for the carrier recovery in OFDM systems. The method comprises the steps of: performing, in transmission, a discrete inverse Fourier transform providing for a number of pilot subcarriers to be transmitted together with subcarriers associated with the symbols of a certain constellation, each symbol being associated with a block comprising a number m of bits; and performing, in reception, a Fourier discrete transform of the received signal. Wherein the method further comprises the steps of arranging the pilot subcarriers in a continuous/flanked manner inside the signal to be transmitted; extracting the flanked pilot subcarriers by band-pass filtering the received signal thus obtaining a first filtered signal, and utilizing such extracted pilot subcarrier to perform a feed forward correction of the phase error to be carried out before performing said Fourier discrete transform.