| 摘要 |
PROBLEM TO BE SOLVED: To generate an excellent high-frequency band signal with simple constitution and to perform practical high-frequency band signal interpolation. SOLUTION: A digital audio signal reproduced by digital audio equipment performing compression is supplied as a source signal to an input terminal 1, and the source signal is supplied to, for example, a Hilbert transforming circuit 2 for generating an analytic signal, whose real part R and imaginary part I are independently extracted. Further, the real part R and imaginary part I are supplied to squaring circuits 3 and 4 respectively and squared signals of them are added together by an adding circuit 5, whose addition signal is supplied to a square root circuit 6 to extract an envelope component of the source signal. The envelope component includes a higher harmonic component. Then, the higher harmonic component of the envelope component extracted by the square root circuit 6 is extracted by a high-pass filter (HPF) 7 and a high-frequency band part of the source signal from the input terminal 1 is removed by a low-pass filter (LPF) 8 to generate a signal; and these signals are added together by an adding circuit 9 and the resulting signal is output to an output terminal 10. COPYRIGHT: (C)2007,JPO&INPIT
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