| 摘要 |
PURPOSE:To improve the S/N of a reproduction signal by correcting a linear predictive coefficient in order to minimize the square mean value of each analysis frame of a difference signal between the input and restoration signals. CONSTITUTION:An adder 23 is added together with delay memories 24-26, a differential device 30 and a coefficient device having linear predictive coefficients alpha'1, alpha'2 and alpha'p. Then a restoration signal x''i (output of an adder 23) is calculated by means of a corrected predictive coefficient alpha'j so that the error of the restoration signal is reduced. The coefficient is corrected so that the square mean value (expected value) is minimized for each analysis frame for an error signal epsiloni (output signal of the device 30) between an input signal xi and the signal x''i. For this purpose, the expected value of epsiloni<2> is partially differentiated with the alpha'j. This partially differentiated value is set at ''0'' to obtain the alpha'j. Then a corrected coefficient alpha'j is decided by supposing that the signals are steady within an analysis frame.
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