| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device that suitably estimate BNP in a short time even in an environment where noise is change with the lapse of time.SOLUTION: A short-period power estimating unit 10 calculates a short-time power average of an input signal (e) as time passes, and outputs a short-period power estimated value Pow_S, and a level variation detector IDG20 inputs the short-period power estimated value and then monitors an increase or decrease of the short-period power estimated value Pow_S at each time, and determines that the input signal (e) is only a noise signal and then holds the current short-period power estimated value Pow_S as a tentative noise level BNL_X when the increase or decrease of the short-period power estimated value Pow_S is extremely small, and determines that the input signal (e) includes a signal to be processed and then estimates the tentative noise level BNL_X as a noise level BNL when the short-period power estimated value Pow_S increases and the number of times of the increase reaches a threshold M. Consequently, the noise level BNP is suitably estimated in a short time even in an environment where the noise is changed with the lapse of time. |
