| 摘要 |
At the time of ordinary communication, up-mixer 108 combines a signal with a frequency f2 from frequency synthesizer 124 with I and Q signals for transmission that are quadrature modulated in quadrature modulator 105, down-mixer 115 combines the signal with the frequency f2 with a received signal, then only in the case of receiving a signal with a frequency fr' different from a frequency fr, frequency synthesizer 125 that generates a signal with a frequency f3 different from the frequency f2 is operated, and frequency synthesizer 125 and down-mixer 115 are connected with switch 127, so that down-mixer 115 combines the signal with the frequency f3 with a received signal. It is thereby possible to switch frequencies fast and with low current consumption in receiving a signal with a reception frequency other than a combination of transmission frequency and reception frequency specified in an ordinary radio system.
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