INTERMEDIATE REPEATER SYSTEM

PURPOSE:To transmit a sub-information signal without any error even in an environment where the quality of a main signal is deteriorated. CONSTITUTION:A code error detector 1 detects the code rule error of the output of an optical signal/electric signal converter 11, and outputs a voltage in proportion to the number of the code rule errors per unit time. A comparator 2 compares a reference voltage with the output voltage of the code rule error detector 1, and outputs a constant voltage when the output voltage of the code rule error detector 1 is beyond the reference voltage. An amplitude modulator 3 increases the modulation factor of the sub-information signal based on the output of the comparator 2.