| 摘要 |
PURPOSE:To perform centralized monitor for main line system effectively, by using auxiliary transmission line. CONSTITUTION:The television signal from the antenna 1 is transmitted to the amplifiers 4-1-4-n having a number of brance outputs in series connection via the head end 2 and the transmission main line 3, and the signal level of every channel is monitored with the level discriminators 7-1-7-7 in the monitor receiver 6, and it is displayed on the display units 8-1-8-7. One of the branches of the amplifiers 4-1-4-n is connected to the auxiliary transmission line 10 via the filters 11-1-11-n passing through one channel signal arbitrarily selected, converters 13-1-13-n making conversion to the signal in specific frequency band to those amplifiers, and band compressors 14-1-14-n. The level discriminators 16-1-16-n in the monitor receiver 6 detect the failure in operation of the amplifiers 4-1-4-n by monitoring the return channel signal level on the auxiliary transmission line 10. |
