Societa Italiana Telecomunicazioni Siemens S.p.a.

Italtel Societa Italiana Telecomunicazioni S.p.a.

Roberto Delle Donne

Luigi Musumeci

A transmitting section of a PCM station in a telecommunication system, embodied in an integrated-circuit chip, comprises a channel-forming circuit receiving a stream of data bits to be organized into a succession of outgoing frames each consisting of a series of channels containing respective 8-bit words or bytes. A multiplexer in the channel former replaces part of a received byte assigned to the No. 0 channel of each frame, including its second and third bits, with certain bits to be included in two alignment words A and B respectively transmitted to a remote terminal at the beginning of alternate frames. The third bit of word B is high when a malfunction is detected or when the replaced second and third bits of the corresponding byte have certain configurations detected by a decoder, calling either for the closure of a loop between the local transmitting and receiving sections or for the monitoring of the PCM line extending to the remote terminal. The latter operation is controlled by a remote-supervision circuit which, in response to either of two such bit configurations, causes the bits of one or more frames to be sent out in either of two representations selectively established by an associated coder.

Transmitting section of PCM station

An incoming bit stream of a first bit frequency, divided into a succession of n-bit words, is converted into an outgoing bit stream of a second bit frequency with the aid of two n-stage buffer registers alternately loaded by two sets of interleaved writing pulses, on every n.sup.th cycle of the first bit frequency, with incoming words which are alternately read out on every n.sup.th cycle of the second bit frequency by two sets of interleaved reading pulses. A logic network detects the coincidence of a reading pulse from one set with either of two guard pulses immediately preceding and succeeding, respectively, each writing pulse of the corresponding set; upon such coincidence, a switching network transposes the two sets of writing pulses to restore an original relative pulse position in which the reading pulses of each set occur substantially midway between writing pulses of the same set.

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Milan, Italy

Roberto Delle Donne