Abstract: The present invention is to provide an optical feedback control unit for determining an optical output by a feedback control, an optical communication system, a feedback control method, and a recording medium for recording a program. According to the present invention, even when used in the system to which a plurality of nodes are connected, the unstable system may become stable by the proper feedback control without being affected by the optical level change according to the polarized variation or the loss variation.

Abstract: The present invention is to provide an optical feedback control unit for determining an optical output by a feedback control, an optical communication system, a feedback control method, and a recording medium for recording a program. According to the present invention, even when used in the system to which a plurality of nodes are connected, the unstable system may become stable by the proper feedback control without being affected by the optical level change according to the polarized variation or the loss variation.

Abstract: A signal size judging apparatus is disclosed that comprises of a separating circuit, a plurality of judging circuit and a connection status deciding circuit. The separating circuit receives the multiplexed signal and separating it into its constituent basic signals for each channel. The judging circuits are provided to correspond to each of the basic signals for each channel except the foremost channel and is supplied with the basic signals for each of the channels from the separating circuit and judges whether or not each basic signal is connected to the basic signal for the immediately preceding channel. The connection status deciding circuit decides as to how the basic signals for all of the channel are connected on the bases of the possible results of judgment performed by the judging circuit.

Abstract: A series-to-parallel converter (26) converts an input code sequence to first to N-th code sequences with input clocks frequency divided by N into circuit clocks, based on which a frame pulse is generated. Among concurrency detectors (41) which are supplied with the frame pulse in common and with detection signals produced when first to N-th synchronization patterns are detected in the respective code sequences and are for producing nonconcurrent results when the detection signals are nonconcurrent with the frame pulse, a particular detector produces an earliest concurrent result to disable other detectors when the frame pulse is concurrent with one of the detection signals that is supplied thereto. These other detectors are enabled when the particular detector produces a nonconcurrent result due to collapse of frame synchronism. Through an AND gate (43), the nonconcurrent results inhibit the circuit clocks.