Patent ID: 7028231

Claim:
An optical transmission system for transmitting a signal having a predetermined frame format from a first element to a second element, wherein the first element comprises: an error-correction coder for coding transmission data to produce a transmission signal subjected to error-correction coding, said error-correction coding allowing for correction of a given number of errors; and a transmitter for transmitting the transmission signal to the second element, and the second element comprises: a receiver for receiving a reception signal subjected to the error-correction coding from the first element; an error-correction decoder for decoding the reception signal to produce decoding failure information, said decoding failure information including a decoding failure flag in the case that the decoding of the reception signal fails; and a decoding failure collector for counting a number of decoding failure flags produced by the error-correction decoder to determine a decoding failure flag count, and for calculating a number of errors after the error correction decoding based on the decoding failure information, said calculating including multiplying said decoding failure flag count by a number greater than said given number.