| 摘要 |
<p>In a data transmission system with radio stations and devices remote from it, e.g. in a cellular mobile radio system, the radio stations transmit radio signals and receive radio signals which in each case contain data signals. According to the invention, as many as possible are shifted from the fixed stations to the remote devices for processing functions. The radio signal to be transmitted from the radio station (2) is generated by generating in the remote transmission device (10) an unmodulated carrier and a carrier modulated with the data signal, where the carriers differ in their frequency by the amount of the carrier frequency of the radio signal (f1). These two optical carriers are transmitted to the radio station (2), where they are mixed in an optical receiver to produce the radio signal containing the data signal. A radio signal which is received in a radio station (40) is optically transmitted to a remote device (44) and is further processed only when it is there. This transmission is carried out in that an optical transmitter (41) present in the remote transmission device (44) generates an unmodulated optical carrier and transmits it to an optical modulator (43) located in the radio station (40). In the optical modulator (43), the light, modulated with the received radio signal, is transmitted back and the radio signal (f1') is obtained by optical heterodyne reception of the unmodulated and the modulated carrier (v0', v1'). …<IMAGE>… </p> |
