| 摘要 |
<p>A fault locating arrangement for a two-way repeatered transmission link comprising a source in one of the terminals to transmit a unique signal in a first transmission direction from the one of the terminals to the other of the terminals through the repeaters, and a first unique signal detector, a second unique signal detector and logic circuitry disposed in at least the other of the terminals and each of the repeaters. The first unique signal detector is coupled to the first transmission direction, the second unique signal detector is coupled to the opposite transmission direction and the logic circuitry is coupled to the first and second unique signal detectors such that, when the unique signal traveling in the first transmission direction is detected, a loop connection is established for the unique signal from the first transmission direction to the opposite transmission direction and the unique signal is transmitted in the first transmission direction beyond an associated one of the repeaters. The logic circuitry breaks the loop connection when the unique signal is detected traveling in the opposite transmission direction and maintains the loop connection when the unique signal is not traveling in the opposite transmission direction. A phase comparator disposed in the one of the terminals responds to the unique signal transmitted in the first transmission direction and received from the opposite transmission direction to provide an indication of the location of a fault in the transmission link.</p> |
