| 摘要 |
PURPOSE:To perform all-wave reception in a single band by setting the local oscillation frequency of the 2nd mixing circuit to an intermediate frequency between the resonance frequency and antiresonance frequency of a solid resonator, and setting the 2nd intermediate frequency to a half as high as the difference frequency between the resonance frequency and antiresonance frequency of the solid resonator. CONSTITUTION:The 1st intermediate frequency amplifier 3 includes a low- impedance driving circuit for the solid resonator and a low-impedance passing circuit, so the highest amplification degree is obtained at the point of a resonance frequency fr where the series impedance of the solid resonator. A signal amplified by the 1st intermediate frequency amplifier 3 is supplied to the 2nd frequency converter 4, which mixes it with the output signal of the 2nd local oscillator 5 to obtain the 2nd intermediate frequency. When the 2nd local oscillation frequency is selected at a halfway point between the resonance frequency fr and antiresonance frequency fa of the solid resonator, the 2nd intermediate frequency Fif2 is fa-fr/2. This 2nd intermediate frequency is selected and amplified by the 2nd intermediate frequency amplifier 6 and demodulated by a detector 7 to obtain a low frequency signal. |
