Title:
SOUND SIGNAL MODULATING SYSTEM
Document Type and Number:
Japanese Patent JP3160031
Kind Code:
B2
Abstract:
PURPOSE: To reduce the deterioration of a program sound signal due to interruption waves by digitally modulating a low band component having much information volume out of the program sound signal and transmitting the digitally modulated component. the direct digital modulation of
CONSTITUTION: An MSK modulator 5 executes the direct digital modulation of a higher harmonic signal formed by a carrier oscillator 6 by using a 4-bit digital signal obtained by an ADPCM coder 4. A frequency-modulated wave having 15kHz band width and fixed amplitude and including 99.5% of the whole energy in a main lobe is obtained from the modulator 5. A high band side signal ≥1.2kHz extracted by an HPF 3 is level-limited by a limiting amplifier 7 and inputted to an AM modulator 8. The modulator 8 executes the amplitude modulation of the MSK-modulated carrier by a higher frequency side signal to obtain a carrier. On the receiving side, a receiving signal is distributed into two signals by a high frequency distributer 10. An amplitude-modulated component is removed from one signal by a limiter 11 and the component-removed signal is inputted to an MSK demodulator 12. A digital signal is decoded to a sound signal by a PCM decoder 13 to obtain the low band side signal in the program sound signal.
Inventors:
Tetsuro Miyazaki
Michihisa Ikuiwa
Nao Naka
Michihisa Ikuiwa
Nao Naka
Application Number:
JP27534791A
Publication Date:
April 23, 2001
Filing Date:
October 23, 1991
Export Citation:
Assignee:
Japan Broadcasting Corporation
International Classes:
H03C1/00; H04B14/00; H04B14/04; H04L27/10; (IPC1-7): H04B14/04; H03C1/00; H04L27/10
Attorney, Agent or Firm:
Hidekazu Miyoshi (5 others)