COMMUNICATION METHOD AND COMMUNICATION DEVICE

摘要

A transmission line is monitored while the communication is held in a steady state and moving a tone set if there are no tones securing a predetermined value of an S/N ratio. The tone set is not moving if there are at least two tones securing the S/N ratio. The tone set is moved by the predetermined method if there is one tone securing the S/N ratio and it is judged that communication quality can be maintained by moving the tone set in a same tone group. The tone group moved if it is judged that the communication quality cannot be maintained even by executing movement of the tone set in the same tone group.