There is an increasing need for digital data transmission system using CATV line today. With the above in mind, we have developed a system which is able to transmit digital data of approximately 7.4 MBPS using a frequency bandwidth of 6 MHz (equivalent to one arbitrary TV channel), and which can also be connected to currently used CATV system without any alteration.
2-level VSB transmission method is employed for this system because of its suitability for the various characteristics of CATV system and simplicity of instrumentation in particular at the receiving side.
The system is also provided with a very flexible data format, enabling a wide application in designing the system. The system enables to simultaneously transmit four ultra-high-fidelity stereo audio programs, as well as computer and game software, facsimile data, still picture, etc. to all or specified subscribers.