Patent ID: 8077761

Claim:
A method of adjusting a reception threshold value, the method being executed by an apparatus for performing data transmission and reception, the method comprising: generating a transmission signal based upon a clock regenerated from a reception signal; setting the reception threshold value at a first initial threshold value; detecting a first bit error rate of the reception signal by repeatedly shifting a phase of the transmission signal by a predetermined value in a state where the reception threshold value is being fixed to the first initial threshold value; determining the phase of the transmission signal at which the detected first bit error rate of the reception signal is maximized, as a worst phase of the transmission signal; and adjusting the reception threshold value to an optimum reception threshold value in a state where the phase of the transmitting signal is being fixed to the determined worst phase, by: setting the reception threshold value at a second initial threshold value, detecting a second bit error rate of the reception signal by shifting the reception threshold value from the second initial threshold value by a predetermined interval in a predetermined direction, and determining the optimum reception threshold value using the detected second bit error rate.