| 摘要 |
In a hybrid fiber/coax access network (NET) with a forward channel and a return channel, the return channel serves to transmit voice and video signals as well as data signals from groups of terminals (NT1; NT2) to a subcenter (HUB). Access by a group of terminals (NT1; NT2) to a shared electric line (KOAX1; KOAX2) is obtained by TDMA, FDMA, or CDMA, for example. An optical network termination unit (ONU) is connected to one or more electric lines (KOAX1; KOAX2). For each line or for each separate frequency range of the return channel, the optical network termination unit (ONU) contains an analog-to-digital converter (A/D1, A/D2) which digitizes the received signal. If two or more analog-to-digital converters (A/D1, A/D2) are provided, the individual digitized signals are multiplexed in a multiplexer (MUX) and then fed to a digital electrical-to-optical transducer (E/O2). The electrical-to-optical transducer (E/O2) converts the multiplexed signals to optical signals, which are then transmitted over an optical cable (FIBRE) to the subcenter (HUB), where they are processed digitally.
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