| 摘要 |
PROBLEM TO BE SOLVED: To prevent step-out and the generation of an unnecessary alarm, when the signal of a spare radio line is switched from a pilot signal to the signal of present radio line and to realize high-speed switching. SOLUTION: The synchronisation establishing system for a line switch device for switching one of plural present radio lines to the spare radio line, where the pilot signal is transmitted at regular time, is provided with frame- synchronizing parts 1071-N, 107A0 and 301 for detecting the position a head frame bit at every present radio line and spare radio line and synchronizing the hunting of frames, position information storage parts 304 and 305 which previously store position information on the head frame bit between the present radio line and the spare radio line and switch-synchronizing parts 302 and 306, referring to position information of the positional information storage parts, when the signal of the spare radio line is switched to the signal of the present radio line from the pilot signal, exchanging the head frame bit of the pilot signal for the head frame bit of the signal of the present line, with respect to the frame synchronizing part of the spare line and switching synchronisation. |
