| 摘要 |
PURPOSE:To realize the branching between three points in the special 2-wire transmission system through the simple circuit connection and by constituting the two units of filter blocks forming the branching filter with two filters. CONSTITUTION:The branching deivce is installed at the middle of the main transmission line between the 1st and 2nd stations A and B in the group-based 2-wire transmission system comprising the high- and low-group bands. Then the branch transmission line is formed between the branching device and the 3rd station C, and then directional filters 5, 6 and 7 are distributed at stations A, B and C each in order to secure the communication between stations A and B, A and C plus B and C each. At the same time, high-band pass filters 8, 9, 12 and 15 plus low-band pass filters 10, 11, 13 and 14 are provided to form the branching filter. Then such constitution is secured for these filters in that two units of the single-unit filter featuring the input and output impedance 0OMEGA and 1OMEGA each are connected vertically and facing in opposite directions to each other. And thus 1/2 of the effective attenuation quantity is applied by these two filters in order to prevent the passing for the signals between stations A, B and C each. |
