| 摘要 |
PURPOSE: A digital demodulation and automatic gain adjustment apparatus of the WLL(Wireless Local Loop) intermediate frequency is provided to get the output signal of a regular level by demodulating a transmitted signal into a QAM(Quadrature Amplitude Modulation) signal and supplying it to the automatic gain control circuit of the intermediate frequency. CONSTITUTION: An automatic gain control part(10) receives the intermediate frequency from the WLL receiving part and maintains a regular amplification rate by a control signal. An A/D converter(40) converts the output signal of the automatic gain control part(10) into a digital signal. A first and a second demodulators(22,27) divide the output signal of the A/D converter(40) into the signals of I(In-phase) and Q(Quadrature-phase). A first and a second digital band restriction filters(32,37) remove unnecessary digital signals and noises from the digital signals of the first and the second demodulators(22,27). A control signal generation part(100) receives the digital signals of the first and the second digital band restriction filters(32,37) and outputs the control signal to control the amplification rate of the automatic gain control part(10).
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