METHOD FOR MONITORING THE QUALITY AND CONTROLLING IDENTIFICATION OF WAVELENGTH CHANNELS AND FOR TRANSMITTING NETWORK MANAGEMENT INFORMATION IN TRANSPARENT OPTICAL COMMUNICATIONS NETWORKS

摘要

To assure the quality of data transmission, the quality of the transmitted data must be tested. A control of the identification of wavelength channels and the transmission of network management information is also required. According to the invention, a test signal, which contains encoded information for identification designation, quality testing and network management in the form of a low-rate digital signal, is optically modulated on a useful signal, which is already modulated on an optical carrier. Said modulation by the test signal can take place at any point in the transparent optical network. The spectral portions of the test modulation lie above the highest spectral portions of the useful modulation. The test signal can be extracted again, after traversing an optical transmission path, at any other point in the transparent optical network for evaluation with regard to information content and quality. The low-rate digital signal is evaluated using known methods with regard to its quality and conclusions are drawn from the determined quality of said low-rate digital signal concerning the quality of the useful signal, as the degradation effects during transmission affect the low-rate digital signal more adversely as a result of its higher frequency portions than the lower-frequency useful signal.