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

Roberto Preti

Gian B Alaria

Digitized message samples or bytes appearing in time slots of an outgoing PCM frame, temporarily allocated to respective local channels such as telephone lines of limited activity, are written during alternate storage periods of, say, 32 ms (each encompassing 256 PCM frames) in a pair of memories from which they are alternately read out in a different sequence to form special packets of interleaved bytes from respective channel pairs or other channel groupings. A number of such special packets are assembled together with other packets from more active channels into an outgoing TDMA frame which forms part of a superframe equal in length to a storage period; the TDMA frames are modulated at an accelerated bit rate upon an r-f carrier for transmission to a relay station aboard a satellite. Upon redistribution of the packets at the relay station according to their respective destinations, they are beamed back to earth for reception by other ground stations. There the special packets of incoming TDMA frames are alternately written, during like storage periods, in another pair of memories from which they are then read out in respective time slots of consecutive incoming PCM frames before being sent to their destinations. A TDMA frame period of each superframe is used to carry a synchronization code generated in the transmitting section and extracted in the receiving section of a ground station for correlating its operation with a clock aboard the satellite.

Growing community of inventors

Turin, Italy

Roberto Preti