Kabelfjernsynssystem hvor informasjonssignaler overföres for flere abonnenter, samt abonnentterminal for anvendelse i et sådant system

摘要

A CATV system uses a single single-mode optical fiber (16) for transmitting a composite optical signal (62) containing television signals in different frequency channels for a plurality of subscriber terminals (14) from a headend terminal (10) to a distribution terminal (12), and converts the transmitted signals at the distribution terminal into electrical signals for distribution to a plurality of subscriber terminals over a plurality of coaxial cables (18). The distribution terminal further receives electrical service request signals (88) from each of the plurality of subscriber terminals, and converts each received service request signal into an optical service request signal (84) for transmission to the headend terminal over the same single-mode optical fiber (16) as used from transmitting the composite optical signal. Wavelength-division multiplexer/demuitiplexers (50,70) couple the optical fiber to the headend terminal and the distribution terminal to enable bidirectlonal transmission. The subscriber terminal is responsive to a control signal transmitted to the subscriber terminal for enabling a receiver (96) therein to receive television signals transmitted to the subscriber terminal over a selected one of said different given frequency channels. The headend terminal includes a digital switch (40) that is operated in coordination with the control signals that are transmitted to the subscriber terminals for enabling reception of only selected frequency channels in the respective subscriber terminals, by frequency positioning the television signal indicated by the service request signal (66) received from a given subscriber terminal witbin the composite signal for transmission to the given subscriber terminal over the given frequency channel enabled by the control signal that is transmitted to the given subscriber terminal.