| 摘要 |
<p>PURPOSE:To reduce the occupation frequency range of a monitor signal as to a main transmission line by selecting a branch transmission line selection signal which is outputted from a central monitor station to the main transmission line by a filter, and rectifying its output and operating a switch. CONSTITUTION:A CATV system consists of the central monitor station 1 and plural low-priority monitor stations 3 connected to the main transmission line 2 branched from the station 1. The low-priority monitor stations while outputting a signal of CATV from the main transmission line 2 to the branch transmission line 4 through transformers 51-54 sends the CATV signal to other low-priority monitor stations through a main transmission line 2'. The branch transmission line selection signal on the main transmission line 2 is inputted to a BPF7 through the transformer 53. When the selection signal coincides with the center frequency of the BPF7, the output of the BPF7 is rectified by a rectifier 8 and the switch 9 is operated with the rectification output. The monitor signal of a repeater on the branch transmission line 4 is outputted to the main transmission line 2 through the switch 9 and transformer 51.</p> |
