Monitoring system for optical transmission line repeaters

DETAILED DESCRIPTION It is an object, therefore, of the present invention to overcome the disadvantages and limitations of a prior optical cable monitoring system by providing a new and improved monitoring system for optical transmission line repeaters.
Another object of the present invention is to provide a monitoring system for optical transmission line repeaters in which an interstitial copper pair are not utilized, and instead, the monitored signal is transmitted through the main optical transmission line.
The above and other objects are attained by a monitoring system for optical transmission line repeaters comprising an optical fiber transmission line for transmitting a digital signal optically, and a plurality of repeaters inserted in said transmission line, characterized in that each repeater has the particular identification code, the transmission terminal at one end of the transmission line transmits the test code having the identification code for identifying the particular repeater and an acknowledgement block with an empty bit position on the time divisional basis with the data to be transmitted, the repeater which finds the same identification code in the test code as that of the present repeater inserts the response signal in said acknowledgement block and repeats the signal including both said test code and the data to be transmitted, and th reception terminal at the other end of the transmission line analyzes the response signal of each repeater to monitor the error rate of each repeaters.
Therefore, the present invention has at least the following features.
(a) Each repeater has the particular identification code.
(b) The test code is inserted in the data to be transmitted on the time divisional basis.
(c) The response signal of each repeater is inserted in a time slot in the test code.