| 摘要 |
<p>The invention relates to the transmission system of a local network (1) allowing the exchange of digital information between the pieces of equipment (2) distributed within an on-board computer system. The transmission system of the local network (1) is composed of an open transmission line formed by two-way point-to-point links (3) connecting the pieces of equipment to their neighbours, and means (4) of connecting up the pieces of equipment to the transmission line. Each piece of equipment is connected up to the transmission line by a sub-system (4) providing for the transmission, reception and propagation of the signals. Within each piece of equipment, this subs-system (4) transmits the digital information simultaneously to its two neighbours. The sub-system (4) selects the first signal received from one of the transmission line segments to which it is coupled, reshapes it in order to propagate it over the opposite segment, and dispatches it to the piece of equipment. The invention is implemented on board railway vehicles. The segments of the transmission line consist of shielded twisted pairs. The point-to-point links are redundant. The transmission code is the FM0 (differential Manchester) code. Access to the transmission line is governed by the protocol defined by ISO standard 8802.4 (token-passing bus). <IMAGE></p> |
