COMMUNICATIONS APPARATUS AND A COMMUNICATIONS METHOD

摘要

When a primary modulation/demodulation method used by existing power line modems connected to the same power line is changed, a concept of a virtual master is adopted. Specifically, if a power line modem among multiple power line modems connected to a power line (7) judges that the communication quality is difficult to ensure by the current primary modulation method, the power line modem serves as a virtual master in a primary modulation change processing. The virtual master sends a change request command presenting the next primary modulation method to the other power line modems. If a change reject command is not replied from any of the other power line modems having received the change request command, the primary modulation method currently used by the power line modem serving as the virtual master is changed to the next primary modulation method and a change instruction command is sent to the other power line modems. Lastly, the other power lines having received the change instruction command change the current primary modulation method to the specified primary modulation method.