| 摘要 |
PURPOSE:To attain the reception of a wider range than the oscillation enable frequency range of a local oscillator by switching a signal of a mixer distributed by a 0-90 deg. distributer and synthesized with a reception signal by the mixer, synthesizing the signal by the 0-90 deg. synthesizer and inverting the output simultaneously with the changeover. CONSTITUTION:When a desired reception frequency is lower than the local signal frequency, the receptible frequency range is the range between fL1-f1F and fL2+f1F where fL1, fL2 are oscillated frequencies of a local oscillator 1 to be varied and f1F is the center frequency of the intermediate frequency. On the other hand, in receiving a high frequency, a changeover switch 6 is switched to a state shown in chain lines in figure. Thus, the receptible frequency change is between fL1+f1F and fL2+f1F. In this case, since the spectrum of the intermediate frequency is inverted, an inverting circuit 8 is operated. In conducting a series of operations as above electrically, the frequency range between fL1-f1F and fL2+f1F and between fL1+f1F and fL2+f1F is obtained continuously.
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