Abstract: A method and apparatus for reducing the phase noise introduced by pointer justification from a synchronous digital hierarchy network in a transmitted numerical signal. In the method and apparatus, occasional redundancies associated with bit justifications and fixed redundancies are combined with occasional prefiltered redundancies associated with the pointer justifications, and the combined signal is filtered in an analog phase locked loop. The occasional redundancies associated with the pointer justifications and at least part of the fixed redundancies with or without bit justifications are prefiltered in two stages, and the prefiltered signals are combined with the occasional redundancies associated with the bit justifications whenever these occasional redundancies are not prefiltered.

Abstract: A system for detecting data spectrum distortion in a transmitted signal, in particular distortion caused by selective fading. The system includes: two blocks in parallel, which act on the spectrum average power of the input signal in an equal but opposite manner (i.e. they have equal slopes but act with opposite effect on the amplitude of the input signal versus frequency); two detectors which detect the average power output from the two respective blocks, each being associated with one of the blocks; and one comparitor for comparing the outputs of the two detectors. The system allows one to detect the asymmetries of the data spectrum and, by adding an AGC and a reference voltage, information related to the notch frequency f.sub.o is also obtained. The distortion measurement obtained in this manner allows one to generate a switching criterion, as a countermeasure for selective fadings in the transmitted signal.

Abstract: The invention relates to a system for initializing transmitters in high capacity digital radio links, in which a digital signal with QAM (Quadrature Amplitude Modulation) modulation is transmitted over a radio frequency carrier wave. The initialization of the transmitter is accomplished by generating a plurality of sinusoidal signals (tones), adding those tones together to simulate a digital singal to be transmitted, sending the simulated digital signal through the transmitter, and adjusting the transmitter to compensate for the intermodulation odd order products developed as a result of the nonlinearity of the power amplifier in the transmitter.

Abstract: A system and related multiplexers/demultiplexers for the transmission/reception of digital television information (video+audio), including high definition information (HDTV). Such transmission typically occurs in packets at various work speeds including, among others, a special transmission in which two data flows are transmitted simultaneously to obtain a single information. The multiplexer is associated with external buffers that receive the data at different speeds, form the packet and generate requests of transmission to the multiplexer that receives them according to preestablished priorities.

Abstract: A process for producing a multilayer device which emits coherent luminous radiation (laser radiation) upon the application of electric power. The device consists of a substrate, a first epitaxial layer, an active layer having a composition which emits luminous radiation of a desired wavelength, an optical and electric confinement layer, a further optical and electric confinement layer and an electric contact layered structure. To concentrate current flow through the active layer, the adjacent layer is implanted with ions of transition elements, preferably Co or Fe, which, when annealed by thermal treatment, have a high resistivity.

Abstract: A subrack for supporting cards and printed circuit boards (PSC) for telecommunication equipment which allows complete use of the space available for these cards and circuit boards, while meeting the DIN 41494-IEC 297 standard, with a pitch at least 4 times lower than the pitch required by this standard. The subrack includes undrilled crosspieces, provided only with grooves, one of which is associated with a positioning toothing with teeth forming a rack, having a pitch equal to half of the pitch of drillings of conventional crosspieces. The teeth are inserted into seats machined into the guide of the printed circuit board, each seat being offset by a quarter of the pitch required by the standard. Therefore, by successive turning the boardguide by 180.degree., a series of real pitches is obtained which is a quarter of the minimum pitch required by the standard.