CATV system and method of judging modulation technique in CATV system

摘要

The present invention is directed to a CATV system in which a broadcasting multiple signal including a plurality of types of broadcasting signals modulated by at least two different modulation techniques is sent to a CATV terminal device from a CATV broadcasting device. In the CATV terminal device, the broadcasting signal corresponding to a requested channel is selected from the sent broadcasting multiple signal. The selected broadcasting signal is sent to a plurality of types of demodulation means respectively corresponding to the modulation techniques. The modulation technique by which the broadcasting signal corresponding to the requested channel is modulated is judged on the basis of data representing the relationship between each of channels sent from the CATV broadcasting device and the modulation technique by which the broadcasting signal corresponding to the channel is modulated. An output of the demodulating means corresponding to the judged modulation technique is selected out of outputs of the plurality of types of demodulating means.