Patent ID: 7362085

Claim:
A power line carrier communication system comprising: a power line; a first communication device; a second communication device; a third communication device, the first, second, and third communication devices being arranged on the power line and performing communications via the power line; a storage section that stores information on a physical position of the first and third communication devices; a detecting section that detects a first communication state between the first and second communication devices, and a second communication state between the second and third communication devices, wherein the first and second communication states are the signal strengths of received signals; a relative position calculating section that calculates a first relative position between the first and second communication devices, and a second relative position between the second and third communication devices based on a ratio of (i) a signal strength received at the first communication device from the second communication device, and (ii) a signal strength received at the third communication device from the second communication device; and an arithmetic operation section that calculates a physical position of the second communication device from the first and second relative positions calculated by the relative position calculating section and the information on the physical position of the first and third communication devices stored in the storage section, and stores information on the calculated physical position of the second communication device into the storage section.