Patent ID: 7418047

Claim:
A communication apparatus for performing data communication by selectively using a single-axis modulation scheme and a two-axis modulation scheme, the communication apparatus comprising: a reception section operable to perform a predetermined reception process on reception data; a data processing section operable to accept as input the reception data from the reception section, perform a predetermined process on the reception data, and output transmission data resulting from the predetermined process; and a transmission section operable to perform a predetermined transmission process on the transmission data outputted from the data processing section, and output a high-frequency signal, wherein the transmission section includes: a first signal generation section operable to generate a single-axis baseband modulation signal for the single-axis modulation scheme; a second signal generation section operable to generate a pair of baseband modulation signals for the two-axis modulation scheme; a modulation scheme selection section operable to, when two-axis modulation is performed, select the pair of baseband modulation signals generated by the second signal generation section, when single-axis modulation is performed and a ratio of transmission power in the single-axis modulation scheme to transmission power in the two-axis modulation scheme has a given value, select a pair of signals including the single-axis baseband modulation signal generated by the first signal generation section and a signal having a fixed value, and when single-axis modulation is performed and the transmission power ratio is double the given value, select a pair of signals into which the single-axis baseband modulation signal generated by the first signal generation section is branched; a quadrature modulation section operable to perform a frequency conversion on a pair of signals selected by the modulation scheme selection section, and output a modulated high-frequency signal; and a high-frequency power amplification section operable to amplify the modulated high-frequency signal outputted by the quadrature modulation section, and transmit a resulting signal from an antenna.