| 摘要 |
PROBLEM TO BE SOLVED: To make a radio receiver improved in receiving characteristic, simplified in configuration and low in cost by performing intermediate frequency signal conversion and demodulation of a receiving high frequency signal based on an oscillation frequency signal produced by the same oscillator. SOLUTION: A mixer 40 converts a receiving frequency signal Fr into an intermediate frequency signal Fif by means of signal F10 obtained by n- multiplying a signal F0 oscillated by a local oscillator 100 by a multiplier 90, a filter 50 eliminates noise, divides it into an in-phase component and an orthogonal component and inputs them to mixers 61A and 61B of a demodulator 60. A phase shifter 63 shifts the phase of the oscillation signal F0, produces a cosine wave component and a sine wave component and inputs them to mixers 61A and 61B, the in-phase component and the cosine wave component, and the orthogonal component and the sine wave component are mixed, filters 62A and 62B extract desired waves and amplify them and after that, a decoder 80 decodes by using both the components. In such a case, it is possible to make the frequency Fif and F0 the same frequency by selecting a multiplication number (n) of the device 90 and to demodulate by using the signal F0.
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