| 摘要 |
<p>PURPOSE:To count a reception frequency with high accuracy by providing a waveform reproduction circuit reproducing a waveform of an intermediate frequency signal from a mixer, and supplying the intermediate frequency signal outputted from the waveform reproduction to a control section. CONSTITUTION:A 2nd IF signal outputted from an amplifier 6 is fed to a demodulator 7 and fed also to a DC voltage output circuit 19 and a waveform reproduction circuit 21. A DC voltage output circuit 19 detects a reception electric field strength from a 2nd IF signal and generates a DC voltage with a pedestal accordingly. The DC voltage is converted into a digital data by an A/D converter 20 and fed to a control section 14. Then the waveform reproduction circuit 21 forms a PLL circuit, applies waveform reproduction to the 2nd IF signal and its output signal is fed to the control section 14. Thus, even when the reception electric field strength is low, the frequency of the reception signal is counted with high accuracy.</p> |
