PURPOSE: To prevent beats from appearing in TV video, by putting carriers of plural channels, sent out of a center, in phase with a channel carrier which has maximum electric field intensity among TV broadcasts in an area wherein a system is installed.

CONSTITUTION: At a center 1 of a CATV system, an exterior antenna 13 is provided and an external signal is amplified by a reception part 31 and inputted to a channel selection part 32. In an area where the CATV system is installed, the channel selection part 32 selects a broadcasting station which has the greatest influence of beat disturbance and supplies the signal to a frequency divider 34 through a BPF33. The frequency divider 34 has, for example, a 1.5MHz output frequency and its output is inputted to the phase detector 39 of a PLL circuit 35 and compared with a frequency-divided signal from a frequency divider 42 through a variable oscillator 40 to stabilize the oscillation of the oscillator 40 at a specific frequency fa. By the output of the circuit 35, a video signal and an audio signal are modulated through a modulator 49, whose output is sent to a trunk line cable 3. Then, PLL circuits 36∼38 output carriers of different channels to prevent beats of TV video.