| 摘要 |
A cable modem is configured to include a tuner having a front end which includes a duplex filter stage and a decoupler stage and a rear end which includes a single conversion tuner. The duplex filter stage couples the tuner to a network, a computer system and the front end decoupler stage. Signals received from the network are directed by the front end duplex filter stage to the front end decoupler stage while signals received from the computer system are directed by the front end duplex filter stage to the network. The front end decoupler stage passes RF signals received at an input thereof to an input of the single conversion tuner coupled to an output of the front end decoupler circuit. The single conversion tuner selects, from the plurality of RF signals received thereby, an RF signal to be converted into an IF signal for output therefrom while rejecting the remainder of the plurality of RF signals. The front end decoupler stage also acts to isolate the single conversion tuner from the input thereof, thereby preventing the rejected ones of the plurality of RF signals, as well as return signals originating within the single conversion tuner stage, from passing back through the front end decoupler stage.
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