Patent ID: 7424230

Claim:
A digital transmission system comprising: a transmitting apparatus that transmits digital data optical signals, and a receiving apparatus that receives the digital data optical signals transmitted over an optical transmission path, converts the digital data optical signals into electrical signals, compares the electrical signals with a predetermined threshold value, and performs decision reproduction, wherein the receiving apparatus comprises: k number of decision circuit sets each having a different threshold value, with one set comprising a plurality, n number, of decision circuits having the same threshold value, each of the plurality, n number, of decision units in each decision unit set being configured to receive a reception signal and make a decision, independently from other decision units, on the reception signal with reference to the same threshold value thereby outputting a decision result; distribution circuits that distribute the electrical signals to the decision circuits; a selection circuit that selects and outputs one decision result from the decision circuits; and a control circuit that controls the selection circuit such that the input of the decision results is received from each decision circuit, a set in which the decision result of n number of decision circuits are the same is selected from all sets, and the decision result of one decision circuit from that one set is selected.