| 摘要 |
The spectrum of a PCM signal is divided into bands. Combinations of a reference band inclusive of a highest frequency band and another band, one of the reference band and other band being normalized, are checked to identify a combination having a highest spectrum distribution correlation. The spectrum having the same distribution as the spectrum distribution of the reference band contained in the identified combination is scaled along an envelope function and added to a higher frequency side than the reference band to generate an output signal. A presence/absence of high frequency components of a PCM signal is detected. Only if there are high frequency components, the spectrum components are added to generate an output signal. It is therefore possible to recover a signal approximate to the original signal from either an original signal with the spectrum components in some bands being suppressed or a signal representative of an original signal containing no spectrum components in the bands or from a signal combining these two signals.
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