Abstract: A duplicate control and processing unit for telecommunications equipment consisting of two identical control units connected together is described. Each control unit (UC0, UC1) comprises a processing unit (UP0, UP1) which can be active or on standby, a peripheral data random access memory (RAM) for data processed during operation, and several peripheral circuits connected to the rest of the equipment. An EPROM (erasable programmable read-only memory) (CCL0, CCL1) in each processing unit contains the copy selection firmware. The data RAM and the peripheral circuits include a respective double gate access circuit (ACC0, ACC1) which allows selective access to the active processor only. The latter performs the writing cycles synchronously on both the duplicate data RAMs, allowing fast recovery of the operative synchronism by the standby processing unit, after switching due to failure of the active processing unit (FIG. 2).

Abstract: A mixed combination strategy combiner for receivers operating in high capacity digital radio links and protected with space or angle diversity is described. The combiner comprises a system which calculates the amplitude dispersion in the spectrum of frequencies of the combined signal and a device which measures the power thereof. On the basis of this information and an appropriate calculation strategy tending to minimize the BER of the equipment, a microprocessor generates signals for gain control of the stage RF of the receivers and for phase shift control for a phase shifter for the local oscillator signal sent to one of the receivers. The calculation strategy consists of minimizing a polynomial function of the power and dispersion values. Dependence of the BER on the f.sub.notch characterizing the dispersion is eliminated, normalizing dispersion in relation to f.sub.notch.

Abstract: An echo cancellation device usable in telephone connections affected by phase-roll is described. The canceller calculates the echo path propagation delay and produces an estimate of the echo signal by digitally filtering the signal originated by the far-end talker. The echo estimate is then subtracted from the actual echo to eliminate listening disturbances. The filter used is of the FIR type with adaptive coefficients updated iteratively by adding algebraically, to the values which they had upon the preceding iteration, a correction term proportional to the estimate error. The frequency of the coefficient updating iterations is a multiple of the rate f.sub.c of acquisition of the voice and echo samples by the canceller.

Abstract: A process on a single insulating substrate for depositing in succession a thin layer of tantalium with high resistivity doped with nitrogen and oxygen, a less thin layer of titanium with low resistivity doped with nitrogen, a layer of palladium and a thick layer of gold. Selective chemical attacks of said layers then permit tracing of conducting lines, resistive lines with greater resistance and resistive lines with less resistance.

Abstract: A predistortion linearizer for microwave power amplifiers wherein a single transistor, e.g. of the GaAsFET type, is subpolarized near the pinch-off condition, and carries out the functions both of a gain expander amplifier for recovery of amplitude distortion of the power amplifier and as a command signal generator for a dephaser element for recovery of the phase distortion of the power amplifier.

Abstract: An image suppression harmonic frequency converter capable of operating in any microwave range is described. Frequency conversion is obtained by making use of a local frequency which is half that of a conventional converter. In particular, the radiofrequency reception signal is converted into an intermediate frequency signal with suppression of the converted image band. Similarly, the intermediate frequency signal to be transmitted is converted into a single side band radiofrequency transmission signal. The converter comprises two harmonic mixers, a first inquadrature radiofrequency hybrid coupler, a second in-quadrature intermediate frequency hybrid coupler, two appropriate duplexer filters, two low-pass filters, two matching circuits, and two decoupling circuits.

Abstract: A process for making metallized holes in a dielectric substrate which, after galvanic growth of the conductive paths delimited by photoresist on the substrate, includes a drilling step of the substrate and electrogalvanic creation of rivets protruding beyond the edges of the holes on the front of the substrate. The steps of completion of the conductive and resistive paths on the front, deposition of metals on the back, reinforcement of the rivets and galvanic growth of the back and of the metals deposited inside the hole then follow.

Abstract: To an output terminal of a hybrid circuit with output signals mutually phase shifted 90 degrees is connected a half-wave line section while to the second output terminal is connected a low attenuation filtering network having a phase characteristic which is -90 degrees at the center frequency and varies with the frequency like a half-wave line section.

Abstract: A clock extractor circuit comprising a frequency divider which derives the clock signal from a signal having a frequency which is a multiple of the frequency of a received bipolar signal input. A correction logic circuit in the frequency divider compares the logic state of the frequency divider with a transition detection signal derived by sampling the bipolar signal at the multiple frequency and, on the basis of the phase error detected, commands a phase correction of the clock signal.

Abstract: A linearizer circuit is described having a main radio frequency or intermediate frequency network and secondary baseband frequency network. The main network includes a directional coupler, a delay line, a phase modulator and an amplitude modulator. The secondary network includes means for amplitude detecting and filtering an input signal and a pair of adjustable-gain amplifiers which receive the amplitude detected signal and on the basis of the gain adjustment act on the two modulators as to give them nonlinear response curves so as to compensate for the nonlinearity of the power amplifier placed downstream from the linearizer.