Cselt-centro Studi E Laboratori Telecomunicazioni S.p.a.

S.i.p. Societa' Italiana Per L'esercizio Telefonico P.a.

Alberto Brosio

Adler Tofanelli

Alfredo Fausone

Renato Ambrosio

Vittorio Seano

A bidirectional digital transmission system with echo-cancellation allows the measurement of the received data signal and the automatic adaptation of the attenuator and of the line equalizer. They are implemented by using circuits already present in a conventional system, in addition to auxiliary circuits.

Bidirectional digital transmission system with echo-cancellation

An emitter of unbalanced pulse-modulated energy, specifically a laser, has a feedback circuit including a first branch detecting the mean amplitude of the emitted energy and a second branch detecting the peak amplitude of its pulses. The second branch includes a band-pass filter, centered on the pulse cadence, followed by a peak detector which may comprise a coherent demodulator driven by a square wave whose frequency corresponds to that cadence. The peak detector generates a control signal for a pulse former whose output signals are superimposed upon a biasing signal from the first branch before being fed to the modulating input of the energy emitter.

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Borgaro Torinese, Italy

Alberto Brosio