| 摘要 |
PURPOSE:To surely eliminate noise, by extracting periodical noises generated with a period almost equal to a prescribed delay time included in an input signal or an output signal, and subtracting it from the input signal. CONSTITUTION:An operation is repeated in such a way that a part including a pulse PN sampled from an output signal So by a switch 8 is attenuated to a micro quantity, for example, around K1=0.001-fold, by a multiplier 9, and it is delayed at a delay circuit 11, and a delayed output is multiplied by, for example, K1 -fold, and after that, it is added on the output of the multiplier 9 at an adder 10, and is returned to the delay circuit 11. While the above feed back is repeated, a random audio signal in the neighborhood of the pulse PN is erased gradually in the output signal of the delay circuit 11, and also, the pulse PN having periodicity is extracted gradually, and only the pulse PN is extracted finally. The pulse PN of the output signal So can be eliminated by subtracting an extracted pulse PN from a demodulation signal at an adder 3.
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