Reduction of Impulsive Noise Included in High-Accuracy Surface Measurement Signal by Using M-Transform

The authors have recently proposed a new signal processing technique called M-transform. In this paper, we propose to use the M-transform for impulsive noise reduction. Since M-transform of a time signal is equivalent to calculate cross-correlation function between the time signal and M-sequence, both impulsive noise and white noise are converted into small-amplitude random signal through the M-transform. These small-amplitude random signals can be removed by use of some non-linear filter. And then, the filtered signal is transformed into time domain through the inverse M-transform and the noise reduction procedure is completed.The proposed filtering technique is applied to reduce impulsive noise included in surface tracing signal measured by an atomic force microscope. From the results of the experiment, it is shown that the proposed works quite well for impulsive noise reduction.