Patent ID: 8135423

Claim:
A communication apparatus comprising: a first generator that generates a first transmission signal based on an information data stream; a second generator that generates a second transmission signal that enables demodulation of the information data stream by being combined with the first transmission signal at a specified timing; a first antenna that transmits the first transmission signal; a second antenna that transmits the second transmission signal; an adjuster that adjusts a transmission timing of at least one of the first transmission signal and the second transmission signal such that the first transmission signal and the second transmission signal arrive in a specific area at specified timings; and a time difference calculator that calculates a time difference between a time the first transmission signal arrives in the specific area and a time the second transmission signal arrives in the specific area, wherein the adjuster adjusts a transmission timing of at least one of the first transmission signal and the second transmission signal based on the time difference such that the first transmission signal and the second transmission signal arrive in the specific area at the specified timings, wherein the time difference calculator calculates the time difference from a round-trip time T 1 of a signal on a transmission path between the first antenna and the second antenna, and a round-trip time T 2 of a signal on a transmission path between one of the first antenna and the second antenna and the specific area; and wherein the time difference calculator calculates the round-trip time T 1 using the second transmission signal which is reflected by the first antenna and received by the second antenna or the first transmission signal which is reflected by the second antenna and received by the first antenna and calculates the round-trip time T 2 using one of the first transmission signal which is reflected in the specific area and received by the first antenna and the second transmission signal which is reflected in the specific area and received by the second antenna.