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几种射频通信接收机原理框图及优缺点
典型的超外差式接收机如下图 振荡器产生一个始终比接收信号高一个中频频率的振荡信号,在混频器将振荡信号与接收信号相减产生一个新的频率即中频,这就是“外差”。 射频信号经天线接收后,经过带通滤波器BPF1的频带选择和低噪声放大器LNA放大,通过 ...
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