| 摘要 |
<p>The invention relates to an information transmission system with a transmission in both directions of transmission, in each case at a different frequency. According to the invention, the transmitting sections (1, 13) and the receiving sections (4, 17) of both terminal stations (I, II) are connected via optical branching elements (8, 10) to a single optical fibre (9) as transmission medium. Optical transfers between the branching connections of the optical branching elements (8, 10) are eliminated by a filter (5, 16) in the adjoining receiving path. Carrier-frequency systems Z12 or Z60, for example, can be used as transmitting sections (1, 13) and receiving sections (4, 17) (Figure 1). Intermediate stations (III) can be correspondingly equipped with optical branching elements (18, 23) and filters (19, 22) (Figure 2). The system according to the invention is particularly suitable for electricity supply companies since a cable with optical fibres can be run directly next to power supply lines without being influenced by interference voltages and, at the same time, the familiar carrier-frequency systems can be used. <IMAGE></p> |
