| 摘要 |
<p>There are provided an upper signal interpolation method and an upper signal interpolation device for forming a preferable upper signal with a simple structure and appropriately performing practical upper signal interpolation. A compressed digital audio signal is supplied, for example, to a Hilbert conversion circuit (2) for generating an analysis signal as a raw signal and a real part R and an imaginary part I of the analysis signal are independently extracted. Furthermore, the real part R and the imaginary part I are supplied to square circuits (3, 4), respectively and the squared signal are added in an addition circuit (5). The added signal is supplied to a square root circuit (6) and an envelope component of the raw signal is extracted. A higher harmonic portion of the extracted envelope component is extracted by a high-pass filter (HPF) (7). On the other hand, a signal is formed by removing an upper portion of the raw signal from an input terminal (1) by a low-pass filter (LPF) (8). These signals are added by an addition circuit (9) so as to perform interpolation of the upper signal components of the digital audio signal.</p> |
