| 摘要 |
PROBLEM TO BE SOLVED: To provide an FM modulation apparatus for a video signal that attains low speed processing without the need for high speed processing so as to facilitate various adjustments to the utmost extent. SOLUTION: A DAC 30 applies digital conversion to an IF signal including an FM-modulated video signal, and an orthogonal modulation section 31 applies orthogonal modulation to the digitized signal to produce components orthogonal to each other and to down-convert them to a baseband (BB). A phase calculation section 37 and a phase difference detection section 60 are used to carry out FM demodulation processing at this baseband. Since the processing above is digital processing, an NCO 34 is used for a local oscillator 34 in the orthogonal modulation section 31, the adjustment and the setting are facilitated, subcarrier setting in FM demodulation sections 13 to 15 are also facilitated, and a specification change in filters 7 to 9 for subcarrier extraction is easily executed by having only to change filter factors. COPYRIGHT: (C)2007,JPO&INPIT
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