| 摘要 |
An arrangement for signaling in a voice communication system having optically fed components employs light wave guides which, in addition to serving for the transmission of the communication signals, also serve for the communication of the signals required for completing and disconnecting connections and for the transmission of energy in the form of light for the energy supply of the subscriber stations. The energy for supplying the subscriber stations is transmitted in the form of unmodulated light. The frequency of the unmodulated light deviates from the fundamental frequency of the light signal transmitted from the switching center to the subscriber station. A diplexer is arranged at the subscriber station for the incoming light and conducts the incoming modulated light to a loudspeaker by way of an optical transfer switch and an optoelectronic transducer and feeds the unmodulated light to an acousto optical modulator. In the switching center, apparatus is provided for periodically interrogating all subscriber stations with short light pulses as to their operating conditions. First and second optical transfer switches are provided in the subscriber substations and are indirectly synchronously actuatable by the subscriber, preferably by the handset. The short light pulses are absorbed by an optoelectronic transducer in the idle condition of the subscriber station and are at least partially reflected by an acousto-optical modulator in the activated condition for an outgoing call. In the case of an incoming connection, continuous light or continuous light pulsed in the call rhythm, of two frequencies is transmitted to the subscriber station for activating the call element. The short light pulses for interrogating the operating condition are dimensioned in terms of pulse length and in terms of pulse-to-pause ratio in such a manner that, on the one hand, the call element is not activated and, on the other hand, no noticeable delay of the completion of an outgoing connection occurs. |
