| 摘要 |
<p>A first frequency converter generates an I-system baseband signal based on a high-frequency received signal and a first local signal with a predetermined frequency band. A second frequency converter generates a Q-system baseband signal based on a high-frequency received signal and a second local signal 90° out of phase with the first local signal. First and second AD converters convert respective amplified I-system and Q-system baseband signals to digital data. First and second over-range detecters detect the over-range of the first and the second CAD converters. An automatic gain controller selects the gain based on the detection information of the over-range and the respective I-system and Q-system baseband signals. An offset setter gives a predetermined offset to the selected gain, and sets a gain after the offset with respect to the first or the second variable amplifier.</p> |
