| 摘要 |
PROBLEM TO BE SOLVED: To detect the phase information of an input signal, at the time of synthesizing and encoding sine waves through a simple process. SOLUTION: The waveform of an input signal on the basis of a speech signal from an input terminal 10 is clipped out at a waveform clipping part 21 by one-pitch period on a time axis, and a zerofill part 22 applies zerofill treatment to the waveform data for the one-pitch period, thereby preparing 2N samples as a whole (N: integer, 2N: value equal to or more than sample number for the one-pitch period). The zerofill waveform data is subjected to an FFT process at an FFT(Fast Fouria Transform) part 13. Then, tan<-1> is calculated at a tan<-1> part 24 using the real part and the imaginary part of the FFT processed data, thereby finding a phase. Thereafter, the phase is linearly interpolated at an interpolation part 25, thereby finding the phase of an input signal for every harmonics. |
