| 摘要 |
In a service integrated, time multiplex digital signal transmission system for transmitting narrowband and broadband signals between a central exchange terminal and a subscriber terminal, which system includes a light conductor path connected between the terminals, a transmitter device at one terminal composed of signal processing circuitry connected for combining the signals provided by sources into a multiplex signal and for supplying such multiplex signal to the light conductor path, and a receiver device at the other terminal composed of signal processing circuitry connected to the light conducting path for separating received multiplex signals into narrowband signals and broadband signals, the device at the subscriber terminal being normally supplied with operating power by local utility mains, a charge accumulator connected for supplying operating power to the device at the subscriber terminal in the event of interruption of the power provided by the mains, one device is provided with an emergency transmitter for producing a narrowband signal and for supplying such signal to the light conductor path, the other device is provided with an emergency receiver for receiving the narrowband signal produced by the emergency transmitter and for receiving such signal from the light conductor path, a detector is located at one terminal for detecting a local mains power interruption, and switching members are connected between the detector and the device at the one terminal for responding to detection of such power interruption to deactivate signal processing circuitry at the one terminal and activate the emergency device at that terminal, |
