BIDIRECTIONAL CATV SYSTEM AND BIDIRECTIONAL CATV REPEATER AMPLIFIER USED THEREFOR

摘要

PURPOSE:To minimize the deterioration of images without cutting off the signals and to send the alarm data to a center monitoring device for quick restoration of a system by reducing the gain of an amplifier in response to the detection level of an unnecessary wave signal and in a range where the images are not affected. CONSTITUTION:The level of the spurious wave signal that is extracted from some of output signals of a down variable amplifier 10 by a spurious wave signal extracting part 12 is detected by a level detecting part 13 and sent to a monitor control part 14. The part 14 transmits a gain control signal to a switch 15 and a monitor signal to an alarm data transmitting part 16 respectively when the signal level detected by the part 13 is higher than an allowable range. The switch 15 gives higher preference to the gain control signal of the part 14 than the AGC signal of a down AGC part 11 and controls the gain of the amplifier 10. Thus all signal levels are reduced in a range where the images are not affected. Meanwhile the part 16 sends the alarm data to a center.