Abstract: The control of the transmission of useful optical signals on different line paths of an optical transmission device is accomplished via at least one of the following features: using signal sources and signal sinks, the useful optical signals are coupled into the line paths, or are coupled out of them; at least one portion of the optical line paths is configured as normal line paths having coupling nodes via which a switchover to an alternative line path can be undertaken if a normal line path is disturbed; in addition to the useful optical signals, test signals, whose evaluation is used for the switchover between the line paths, are transmitted bidirectionally section-by-section; at least two types of test signals can be transmitted, of which a first type is used as an indicator for an intact line path and a second type as an indicator for a disturbed line path; and any switchover to an alternative line path is only undertaken if, before the detection of the disturbance, a test signal of the first type has be

Abstract: For checking the transmission in an optical transmission installation with optical fibers for conducting optical useful signals between signal sources and signal acceptors (S/D), at which optical useful signals are coupled into or outcoupled from the optical fibers, which signals can be diverted to substitute paths at nodes (OCC) of the transmission device, checking signals (LS) are transmitted in both directions between the signal sources and signal acceptors (S/D) and nodes (OCC) as applicable in the respective optical fiber for at least one useful signal. The presence of the checking signals (LS) is checked, and in the absence of a checking signal (LS) from one line direction, the transmission of a checking signal (LS) in the opposite direction is suppressed. In this way it is assured that on both sides of a line problem, this problem will be detected and an alarm will be tripped if necessary, or a switchover will be made to a substitute path.

Abstract: The control of the transmission of useful optical signals on different line paths of an optical transmission device is accomplished via at least one of the following features: using signal sources and signal sinks, the useful optical signals are coupled into the line paths, or are coupled out of them; at least one portion of the optical line paths is configured as normal line paths having coupling nodes via which a switchover to an alternative line path can be undertaken if a normal line path is disturbed; in addition to the useful optical signals, test signals, whose evaluation is used for the switchover between the line paths, are transmitted bidirectionally section-by-section; at least two types of test signals can be transmitted, of which a first type is used as an indicator for an intact line path and a second type as an indicator for a disturbed line path; and any switchover to an alternative line path is only undertaken if, before the detection of the disturbance, a test signal of the first type has be