| 摘要 |
PURPOSE:To change over the lines of important lines in a short time, by transmitting a pilot signal on the important line in parallel to a spare line at all times, in a line switching system having one spare line in a plurality of common lines. CONSTITUTION:The 1st and 2n common lines are formed with polot signal generators 102, 202, branch circuits 103, 203, transmission lines 106, 206, pilot signal receivers 107, 207 and switching circuits 108, 208. the spare line is formed with switching devices 104, 204, a pilot signal generator 301, a spare transmission line 6, and a pilot detector 7. For example, in case that the 2nd common line is the important line, a signal of the pilot signal generator 202 of the common line is transmitted to the spare line at all times. Then, if the 2nd common line is failed, a pilot detector 7'' receives the pilot of the 2nd common line and after the normal operation of the spare line is confirmed, the common line is changed over to the spare line quickly. Further, the changeover of the 1st common line is performed conventionally. |
