| 摘要 |
PROBLEM TO BE SOLVED: To generate a broad-band noise signal with a constant frequency density within a short processing time. SOLUTION: A spectrum of a desired noise signal is divided into a low-frequency side and a high-frequency side with a frequency Fa, becoming equal to 1/M of an upper-limit frequency F<SB>MAX</SB>of the spectrum, defined as a boundary of both the sides. With respect to each frequency band, spectral data are produced in which a value, obtained by dividing an M-fold value of a desired frequency resolutionΔF into the upper-limit frequency F<SB>MAX</SB>, is defined as a point number N to be subjected to an inverse Fourier transform. An interpolation process with an M-fold magnifying power and a low-pass filter process with a bonding frequency Fa are applied to temporal waveform data Da(k) obtained at the low-frequency side to produce temporal waveform data Da(k)" corresponding to the desired frequency resolution. Then, delay times different in M ways are applied to temporal waveform data Db(k) obtained at the high-frequency side and then the data thus created are frequency-converted into a high frequency region equal to and higher than a bounding frequency at a carrier frequency with a frequency difference equal to the desired frequency resolution. Then, the data converted are again converted into the plural number M of temporal waveform data Db1 (k) to DbM (k) and the data thus converted are synthesized with the temporal waveform data at the low-frequency side, thus obtaining the desired noise signal. COPYRIGHT: (C)2008,JPO&INPIT
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