| 摘要 |
PROBLEM TO BE SOLVED: To realize the digital information delivery service in the CATV system with a simple configuration at a low cost. SOLUTION: A master center MS is connected to a center S that sends information to a CATV network N via an optical transmission channel CL. The master center MS applies 64 quadrature amplitude modulation(QAM) to a multiplex digital video signal received from a satellite 1 to generate a QAM signal. The generated QAM signal is fed to each center S via the optical transmission channel CL. The center S applies frequency multiplexing to the QAM signal and an analog video signal and sends the multiplexed signals to the CATV network N. Thus, an expensive equipment such as a QAM modulator is provided only to the master center, and each center has only to be provided with a comparatively simple equipment that multiplexes the QAM signal onto the frequency multiplex signal, then the entire configuration is simplified and the cost is reduced. |
