| 摘要 |
PROBLEM TO BE SOLVED: To provide a modulation device, information transmission system, audio signal processor, and modulation method to largely reduce noises by simple processing and have little restriction at the time of communications. SOLUTION: In this information transmission system, the modulation device creates an audio signal Sa by performing a higher harmonics providing process to an audio signal Sin to be input, removes the components of the higher frequency band, and sounds a modulation audio signal Se modulated by frequency-shifting and superimposing the components of the frequency band part of the remaining frequency band to the removed frequency band by shift quantity in response to the coding information concerning the transmission information. On the other hand, a demodulation device can recognize the shift quantity of frequency from the collected modulation audio signal Se and demodulate the shift quantity to the coding information. Thereby, even when hearing the sounded audio signal Se, the sense of incongruity on the audibility concerning modulation can be reduced. COPYRIGHT: (C)2010,JPO&INPIT |
