| 摘要 |
A tuner is provided for selecting for reception any one of a plurality of channels in a broadband radio frequency signal supplied to its input. The tuner comprises a plurality of stages, at least some of whose gains and power consumptions can be adjusted by a controller in accordance with prevailing reception conditions. A frequency changer and variable gain amplifier provide a first filtering arrangement to reject non-adjacent channels and a tuneable filter rejects substantially all but the selected channel. Signal levels before the first filtering arrangement, between the first filtering arrangement and a second filtering arrangement formed by the tuneable filter, and after the second arrangement are supplied to the controller, which adapts the gain structure and/or individual stage power consumptions according to the prevailing reception conditions so as to provide an adequate performance for demodulation while reducing power consumption when extreme reception conditions are not encountered.
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