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

Cselt- Centro Studi E Laboratori Telecommunicazioni Spa

Renzo Bortignon

Piero Belforte

Incoming and outgoing lines on opposite sides of a PCM coupling network, each carrying a recurrent frame with a multiplicity of 8-bit channels which are to be individually tested, have branches extending to an input-side data extractor and an output-side data extractor of substantially identical construction co-operating with a control device such as a microprocessor serving to compare the data extracted in a given time slot from an incoming line with those extracted in a corresponding time slot from an outgoing line coupled thereto. Each extractor, realized in integrated circuitry, comprises a multiplexer for selecting one of the associated lines, a register storing the identity of the line to be selected, and presettable counters stepped by a time base synchronized with the PCM system for enabling the loading of an output register by the multiplexer at the instant when a byte of the desired channel appears on the chosen line. The line-identifying register and the presettable counters are loaded with numerical data from the control device with the aid of several cascaded decoders responsive to instruction from that device.

Data-extraction circuitry for PCM communication system

A transceiver inserted between a signal source and a two-wire or one-wire line, designed to transmit balanced or unbalanced digital signals to a remote station at the opposite end of the line while receiving similar signals from the latter station, comprises a first and a second amplifier with inputs connected to the line at a proximal and a distal end of a line-terminating impedance, respectively. Each amplifier has an inverting output connected to a noninverting output of the other amplifier, the two nodes formed between the interconnected outputs being connected to respective inputs of a differential third amplifier feeding a signal receiver. The gain of the first amplifier is half that of the second amplifier whereby the locally generated signals are suppressed in the output of the third amplifier. The several amplifiers are realized in integrated circuitry and may be provided with switches for selective changeover between a balanced and an unbalanced mode of operation.

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Turin, Italy

Renzo Bortignon