Nec Corporation

Nippon Hoso' Kyokai

Yasuhiro Hasimoto

Makoto Ishii

Masatoshi Hamada

Isao Ikai

Yoshio Tachioka

A digital FM modulator includes an A/D converter, a multiplier, an adder, a direct digital synthesizer, and an addition data output circuit. The A/D converter digitally encodes an input modulation signal. The multiplier multiplies an output from the A/D converter and multiplication data input from an external circuit. The adder adds output data from the multiplier to addition data. The direct digital synthesizer changes an oscillation frequency on the basis of output data from the adder with respect to a reference frequency of a reference oscillator. The addition data output circuit changes the addition data to prevent a center frequency from changing in accordance with the multiplication data and outputs the addition data.

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Tokyo, Japan

Yasuhiro Hasimoto