Hello all In the picture attached below VNA, vector net analyzer is not present in the Opti System libraries, and I replaced it with a sine generator in addition to an RF Spectrum Analyzer. Is this true? My second question: I suffer from a problem connecting the ring2. I do not know whether the optical fibers used are unidirectional or bidirectional, and there is a problem when I reconnect the optical fiber in ring2 to the optical coupler. No signal appears on the optical Spectrum Analyzer. Do you have information that can help me about the Vernier effect? I have attached the research paper and the simulation to the Opti System program. Best Regards.