| 摘要 |
PURPOSE:To reduce cost, to miniaturize the device and to improve reliability by setting a proper pseudo line resistance value only by setting an output level, and simplifying the configuration of an input circuit in the status monitor of an amplifier connected to the communication line of a CATV. CONSTITUTION:A status monitor 1 for CATV is provided with an automatic gain control (AGC) circuit 2 to automatically control the gains of amplifiers 21 and 22, standard gain setting resistor VR to set the gain setting value of the amplifier due to the AGC circuit 2 at a prescribed standard gain, changeover switches SW 1 and 2 to change over the AGC circuit 2 to the side of the standard gain setting resistor, arithmetic control part 6 to calculate an input level from difference between the real output level of the amplifier and the output level in the case of setting at the standard gain and to calculate the increase/ decrease value of pseudo line resistance 25 installed at the communication line from difference between the calculated input level and the specified input level, and display part 7 to display the increase/decrease value of the pseudo line resistance calculated by the arithmetic part. |
