| 摘要 |
PURPOSE:To attain no adjustment and to relieve the load of the hardware by applying D/A conversion to an output of a digital oscillator and multiplying the result with a reference frequency signal so as to apply frequency conversion. CONSTITUTION:A digital oscillator 2 outputs sinusoidal wave information with different oscillating frequency in response to a supplied control data Dc. The sinusoidal wave information is converted into an analog quantity at a D/A converter 5 and fed to a multiplier 6. On the other hand, a reference frequency from a reference clock oscillator 3 is fed to a multiplier 5. Then the multiplication output from the multiplier 6 is fed to a BPF 7, where only a desired frequency band component is extracted as an output signal So. Thus, a low oscillating frequency is enough as to the digital oscillator and the load of the hardware is relieved. Further, a ceramic filter or the like is used for a filter means to attain no adjustment.
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