| 摘要 |
In a digital FM demodulating apparatus of this invention, an input video signal is converted into a predetermined digital FM signal, e.g., Asin theta by a recording signal processor and supplied from an input terminal to a phase shift circuit. The phase shift circuit divides digital FM signal Asin theta into digital FM signals Asin theta 2 and Acos theta 2 phase-shifted from each other through 90 DEG and outputs the signals directly to an operational circuit. The digital FM signal Asin theta is converted into digital FM signals A'sin theta 1 and A'cos theta 1 delayed from signals Asin theta 2 and Acos theta 2 by predetermined periods by registers and supplied to the operational circuit. The operational circuit calculates signals Asin theta 2, Acos theta 2, A'sin theta 1 and A'cos theta 1. A result of tan-1 conversion of an output from the calculator performed by a ROM having a tan-1 conversion table is obtained as a value obtained by differentiating a phase component of signal Asin theta by a time from an output terminal.
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