IN-PRIVATE CATV SYSTEM, DOWN-CONVERTER, UP-CONVERTER, AND AMPLIFIER

摘要

PROBLEM TO BE SOLVED: To provide a private CATY system, where a terminal uses an up- converter to convert an incoming signal into a private incoming signal with high frequency and a connection point to an external system uses a down- converter to convent the private incoming signal into the original incoming signal, that can accurately convert the frequency, without the need for using a pilot signal from the external system. SOLUTION: The down-converter 10 is provided with a reference oscillation circuit 36, that generates an outgoing signal and a reference signal with a frequency lower than that of the private incoming signal, uses the reference signal to convert the frequency of the private incoming signal and transmits the reference signal to a transmission line L at the terminal. A bidirectional amplifier 12 on the transmission line L can amplify the outgoing signal and the private incoming signal bidirectionally and also transmits the reference signal to the up-converter 20 at the terminal. The up-converter 20 extracts the transmitted reference signal and uses it to convert the frequency of the incoming signal into the frequency of the private incoming signal.