Nippon Hoso' Kyokai

Kabushiki Kaisha Toshiba

Nec Corporation

Masatoshi Hamada

Makoto Ishii

Nobuhiko Kawai

Yasuo Takahashi

Tatsuya Ishikawa

Yasuhiro Hashimoto

Toshio Aoki

Nobuyuki Miki

Yoshio Tachioka

Yasuhiro Hasimoto

Kenji Ueoka

Hirokazu Toyota

Isao Ikai

Transmitting apparatus and receiving apparatus based on phase modulation

In this invention, in order to generate a VSB modulation signal from a digital baseband signal, an in-phase component of a modulation signal having a frequency spectrum having a high-frequency component whose level is half that of its low-frequency component, and an orthogonal component of the modulation signal of a high-frequency component having a frequency spectrum whose level is half that of the low-frequency component are generated from the baseband signal. The in-phase component and the orthogonal component are multiplied with carrier signals to obtain a carrier in-phase component and a carrier orthogonal component. The carrier in-phase component and the carrier orthogonal component are synthesized to obtain a VSB modulation signal.

Digital type VSB modulation apparatus

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.

Digital FM modulator using direct digital synthesizer

Growing community of inventors

Tokyo, Japan

Masatoshi Hamada