Optical fiber cable service system provided with video on demand service

DETAILED DESCRIPTION The object of the present invention is to provide an optical fiber cable service system capable of incorporating VOD service having a high concurrent utility rate, and further capable of flexibly responding to an increase in the number of VOD service users, without any serious change of optical transmitting equipment or without any necessity of relaying the optical transmitting network.
The above object can be achieved by the optical fiber cable service system constructed as follows.
In the CATV center, a plurality of video signals for broadcasting service are frequency-multiplexed, then optical-modulated, thereby obtaining a first optical-modulated signal.
Furthermore, at least one video signal for VOD service which is requested by a plurality of subscribers is frequency-multiplexed, and then optical-modulated, thereby obtaining a second optical-modulated signal.
Then, the first and second optical-modulated signals are multiplexed and transferred to subscribers' households through the optical transmission paths.
In the subscribers area, the transferred optical-modulated signals are converted into electric signals to reproduce frequency-multiplexed signals, and desired programs are selected.
As a result, it becomes possible to use different modulated optical wavelengths and different optical modulation methods between video signals for broadcasting service and for VOD service.
Consequently, the restriction on the number of carriers in the VOD band is avoided, and VOD service with high concurrent utility rate can be incorporated without any serious change of optical transmitting equipment or without any necessity of relaying the optical transmitting network.
In addition, it also becomes possible to construct a broadcasting system in accordance with the concurrent utility rate.