Abstract: A method for extracting a subset of data from an ordered set of bi-dimensional matrices (data arrays) such as a sequence of pictures or a multi-dimensional matrix, for instance, is implemented by dedicated hardware that may be used each time it is necessary to extract a subset of data from a data array. For each matrix of data, the method calculates very quickly row and column indices of border data of the portion to be extracted, which are obtained by arithmetical operations among row and column indices of vertices of a closed area of interest. The method is implemented in a device for selectively transferring a data stream sampled at a certain bit-rate to a microprocessor unit or to a memory receiving the data stream at a different rate.

Abstract: A method for extracting a subset of data from an ordered set of bi-dimensional matrices (data arrays) such as a sequence of pictures or a multi-dimensional matrix, for instance, is implemented by dedicated hardware that may be used each time it is necessary to extract a subset of data from a data array. For each matrix of data, the method calculates very quickly row and column indices of border data of the portion to be extracted, which are obtained by arithmetical operations among row and column indices of vertices of a closed area of interest. The method is implemented in a device for selectively transferring a data stream sampled at a certain bit-rate to a microprocessor unit or to a memory receiving the data stream at a different rate.

Abstract: The circuit includes an electro-optical mixer, such as an electro-optical Mach-Zehnder modulator, with non-linear behavior. The modulator receives as input an optical signal (Pin) at the frequency to be divided, in addition to an electric signal (e3) at a given frequency, usually corresponding to the frequency deriving from such division. The output optical signal (Pout) from modulator exhibits a modulation spectrum containing the frequency difference between the frequency to be divided and at least one harmonic of the frequency of the above electric signal. After having been converted into an electric signal (e1), the output signal of the mixer is subjected to a filtering action to extract the above frequency difference component. This latter one is then used both as electrical signal (e3) for the mixing, and as output signal from the divider (e2). The preferred application is to OTDM systems, to extract a synchronism signal as tributary signal frequency.

Abstract: The circuit includes an electro-optical mixer, such as an electro-optical Mach-Zehnder modulator, with non-linear behavior. The modulator receives as input an optical signal (Pin) at the frequency to be divided, in addition to an electric signal (e3) at a given frequency, usually corresponding to the frequency deriving from such division. The output optical signal (Pout) from modulator exhibits a modulation spectrum containing the frequency difference between the frequency to be divided and at least one harmonic of the frequency of the above electric signal. After having been converted into an electric signal (e1), the output signal of the mixer is subjected to a filtering action to extract the above frequency difference component. This latter one is then used both as electrical signal (e3) for the mixing, and as output signal from the divider (e2). The preferred application is to OTDM systems, to extract a synchronism signal as tributary signal frequency.

Abstract: The circuit includes an electro-optical mixer, such as an electro-optical Mach-Zehnder modulator (2), with non-linear behaviour. The modulator (2) receives as input an optical signal (Pin) at the frequency to be divided, in addition to an electric signal (e3) at a given frequency, usually corresponding to the frequency deriving from such division. The output optical signal (Pout) from modulator (2) exhibits a modulation spectrum containing the frequency difference between the frequency to be divided and at least one harmonic of the frequency of the above electric signal. After having been converted into an electric signal (e1), the output signal of the mixer is subjected to a filtering action (8) to extract the above frequency difference component. This latter one is then used both as electrical signal (e3) for the mixing, and as output signal from the divider (e2). The preferred application is to OTDM systems, to extract a synchronism signal at tributary signal frequency.

Abstract: The method realizes the frequency control of a frequency standard including an atomic or molecular beam resonance apparatus with two microwave cavities, to which an electromagnetic field is fed, whose frequency is modulated in time with a sinewave signal about an interrogation frequency near to the characteristic resonance frequency of a selected transition of the atoms or molecules of the beam. In the resonance device a current is generated, proportional to the number of atoms or molecules of the beam which have undergone said transition as an effect of their passing through the cavities. The method includes the step of extracting from said current the component whose frequency is an odd harmonic of the modulation frequency of an order higher than the first, in particular the third.