DOMESTIC CATV SYSTEM, DOWN CONVERTER AND UP CONVERTER

摘要

PROBLEM TO BE SOLVED: To accurately perform frequency conversion, without having to use a pilot signal from an external system in a domestic CATV system where an up converter is used to convert an up signal to a domestic up signal of a high frequency on the terminal side and a down converter is used to convert the domestic up signal to the original up signal at a connection point to the external system.;SOLUTION: A down converter 10 takes the output of a reference oscillation circuit 37 consisting of a crystal oscillator as a reference signal and generates a local signal of a certain frequency to a PLL circuit 38 and a local oscillation circuit 36. The generated local signal is attenuated by an attenuation circuit 39 and then is supplied to an up converter 20 via a transmission line L. Since mixers 34 and 54 of converters 10 and 20 use the same local signal to perform frequency conversion of a domestic up signal and an up signal respectively, the down converter 10 can accurately restore the original up signal from the in-house incoming signal.;COPYRIGHT: (C)2001,JPO