| 摘要 |
PURPOSE:To ensure the steady reception through a simple constitution by supplying the signals based on the variable oscillator circuit at the AM receiving time as well as the output signals of the synthesizer fixing oscillator circuit at the FM receiveing time to PLL respectively to use them as the local oscillation frequency. CONSTITUTION:The AM reception system detects (18) the electric wave received through antenna 11 via first and second mixers 14 and 16, and the FM system leads the reception wave of FM antenna 31 to mixer 34 for demodulation 36. When the AM frequency band is received, the signals based on variable frequency oscillator circuit VFO41 are supplied to PLL41. Then the first frequency conversion is carried out through mixer 14 with the output signal of PLL41 used as the first oscillation signal. At the same time, the second frequency conversion is performed through mixer 16 with the output signal of synthesizer fixing oscillator circuit 42 used as the second local oscillation signal. On the other hand, the output signal of circuit 42 is supplied to PLL40B when the FM frequency band is received, and the output receives frequency conversion 44 in the form of the local oscillation signal. In this way, both AM and FM can be received through a simple constitution. |
