| 摘要 |
PURPOSE:To make the step change in a reception frequency equal to the change in the step changes between local oscillators and to adjust the reception frequency minutely, by providing plural local oscillators in which the frequency is changed in different steps and a controller controlling the frequency of the oscillators individually. CONSTITUTION:A frequency f0 of a signal inputted from a high-frequency input terminal 1 is applied to the 1st mixer together with the oscillation signal of the 1st local oscillator 12, is converted into the 1st IF signal and inputted to an IF amplifier 4. The output of the amplifier 4 is applied to the 2nd mixer 5 together with the oscillation signal of the 2nd local oscillator 13, is converted into the 2nd IF signal is frequency fi2 and outputted. The oscillators 12, 13 are provided with a controller 14, the control of which varies the oscillation frequency of the oscillators 12, 13. Further, the controller 14 performs control so as to establish the relation as f0=fL1 fL2 fi2, where f0 is the reception frequency, fL1, fL2 are frequencies of the oscillators 12, 13 and fi2 is the 2nd IF from the output terminal 7. |
