Method for the recognition of the outage of one or more transmission channels in a redundantly designed optical transmission system

Claim 1

An outage recognition device for a redundantly designed optical transmission system having at least two receiver circuits at each station of the system and each receiver circuit having an input and an output with the input being connected to a separate transmission channel, said device determining an outage in each channel and comprising a separate first means connected through the output of each receiver circuit of the receiver circuits for creating an output signal for a first time constant for each bit of data received from the receiver circuit, second means for receiving the output signals from two of the first means and creating a positive signal only when one of the output signals is being received, a pair of first AND gates with one AND gate receiving the output signals from both the second means and the first means of one channel and the other AND gate receiving the output signals of both the second means and the first means of the other channel, each of the first AND gates having its output connected to both a separate third means and to a separate delay means, the delay means for each of the first AND gates delaying the signal of the AND gate by a specific time duration and applying it to one of a pair of second AND gates and the third means for the same first AND gate having an output connected to the same second AND gate, said third means creating a zero signal for a second time constant for each signal received from the first AND gate and then applying a positive signal so that the output of the second AND gates are zero when both channels are without failure and when a channel fails, the second AND gate of the other channel will have a pulse signal.