| 摘要 |
PROBLEM TO BE SOLVED: To provide a radio unit, where miniaturization and reduction in current consumption can be attained by eliminating fluctuations in a transmission frequency just after application/interruption of power of a drive amplifier. SOLUTION: This radio unit has a transmitter that is provided with a synthesizer 1 that generates a carrier signal, an attenuator 2 that attenuates the level of the carrier signal, a drive amplifier 4, a modulator 7 that modulates the carrier signal with a modulation signal received separately and outputs a transmission signal, a power switch 5 that turns on/off a power supplied to the drive amplifier 4 in response to a transmission on/off control signal received from a terminal 11, and a transmission signal generating section 20 having a CPU 6 which is an attenuation signal generating means that outputs an attenuation control signal to change the attenuation of the attenuator 2, in response to the transmission on/off control signal and the radio unit also has a receiver that receives the transmission signal. The attenuation of the attenuator is changed by using a function, that is inversely proportional to an amplitude characteristic of the demodulation signal, so as to make the leading/trailing of the carrier signal outputted from the drive amplifier equal to the characteristic of the modulation signal.
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