Patent ID: 8224181

Claim:
A protection device for removing signal interference in a passive optical network in which a central optical cable is split into several optical branching lines at a branching point, comprising: a plurality of taps, wherein a tap is in each case provided in at least some of the branching lines in order to tap off an optical signal flowing in the respective branching line to the central cable; a plurality of switches, wherein a switch is in each case provided in at least some of the branching lines in order to turn off the respective branching line; a control device configured to, when signal interference occurs in the operation of the passive optical network, carry out a detection of whether the optical signal tapped off by the tap in a respective branching line is a digital signal level sequence of a multiplicity of signal levels, the level values of which exclusively are a predetermined Low level and a predetermined High level, wherein the switch in the respective branching line turns off the respective branching line in the case where there is no digital signal level sequence; said control device including, in at least some of the branching lines, in each case a converter device arranged at the tap for converting light energy of the tapped-off optical signal into electrical voltage for controlling the switch in the respective branching line, wherein the converter device carries out the detection in such a manner that, in the case where the optical signal tapped off is not a digital signal level sequence, the voltage generated by the converter device assumes a value which causes the switch in the respective branching line to be turned off; and said converter device further including a photodiode and a capacitor which interact in such a manner that the photodiode, when receiving light energy from the tapped-off optical signal, charges the capacitor, the switch in the respective branching line being turned off by the charge of the capacitor when the charge of the capacitor is adequate.