| 摘要 |
A simple two-way communication link by means of which data signals from a number of data inputs 17 at spaced positions along a highway 11 can be fed in individually in any desired sequence comprises a highway 11 constituted by an optical fibre; a gas laser 13 or other source of electromagnetic radiation of optical frequency at the end of the highway; a number of outstations 17 at spaced positions along the highway, each of which outstations comprises a modulator 18 for modulating a data signal onto a subcarrier which periodically varies the optical path lenght of a section of the highway with the modulated data signal, and has an associated receiver 20 for signals for controlling operation of the modulator; and, connected to the other end of the highway, a demodulator 16 and transmitter 21 for transmitting control signals to the receivers 20. Preferably the transmitter 21 and the receivers 20 are electrically interconnected by a pair of electric conductors constituting a leaky electric cable 12. |
