Passive optical telecommunication system for narrow band and broadband integrated services digital networks

In a passive optical communications system of the type in which each of a plurality of decentralized equipment is connected via a respective light waveguide line, a respective optical brancher and an optical waveguide bus to a common light waveguide terminal of a central switching center, in which the signal transmission from the central switching center to the plurality of decentralized equipment proceeds on a time-division multiplex basis, clocked by a system clock, in a burst stream from which each of the decentralized equipment accepts only a respective burst intended therefor, and in which the signal transmission proceeding from each of the decentralized equipment to the central switching center proceeds according to a time-division multiple access method in which each burst is transmitted in a synchronized fashion with the assistance of a respective delay in each of the decentralized equipment which is set for that particular decentralized equipment proceeding from the central switching center to obtain a desired reception phase relation, the improvement wherein:

• each of said decentralized equipment consisting means for transmitting a respective burst before a transmission time required for the desired reception phase relation of the burst in the central switching center only after a rough-first predetermined delay time of at least one multiple of the system clock period;
• and
• means in said central switching center for providing a fine, second predetermined delay time for the respective burst incoming from a respective decentralized switching center to produce the desired reception phase relation.