PURPOSE: To make it possible to set a system length according to the initial design value, by adjusting increment or reduction of the submarine repeating system length by increment or reduction of the cable length at both ends of an ocean block equalizer and by giving change to loss of the equalizer to equalize the cable length.

CONSTITUTION: The system is so designed that the length of cable 3, the sum of the length of cables 2-1 and 2-2 in both sides of ocean block equalizer OBE1, and constant loss of OBE1 may be Akm, Bkm, and Cdb respectively. In case that cable loss after production is increased more than the design value by E%, cable length A' is expressed by expression -1 and is shortened by A-A' if cable loss is held in the standard value with standard loss per cable 1km as Fdb. Shortened components of the cable are compensated by extending the cable length at both ends of OBE1, and loss increment dependent upon this extension is compensated by reducing constant loss of OBE1 to C' expressed by expression -2. G in expression -2 indicates that the equalization block of OBE is the G block.