Patent ID: 7684770

Claim:
A transmission device comprising: a modulator for modulating data by a plurality of modulation methods; and a transmitter for transmitting a radio signal by using a plurality of carrier frequencies, wherein the transmission device transmits the data by changing a transmission communication method to another method following a lapse of time, which transmission communication method is formed by combining one of the modulation methods and one of the carrier frequencies, and wherein the transmission device is configured to transmit the data repeatedly without changing the transmission communication method during a time period in which a receiving device is configured to sequentially switch through a plurality of different reception communication methods, each of the plurality of different reception communication methods formed by combining a respective one of a plurality of different demodulation methods and a respective one of the plurality of carrier frequencies at different times during the time period, each of the plurality of different reception communication methods formed of respectively different combinations of the different demodulation methods and carrier frequencies.