A Wavelet Threshold Function for Treatment of Partial Discharge Measurements

Based on the wavelet transform filtering theory, the chapter will describe the elaboration of a wavelet threshold function intended for the denoising of the partial discharge phenomenon measurements. This new function, conveniently named Fleming threshold, is based on the logistic function, which is well known for its utility in several important areas. In the development is shown some variations in the application of the Fleming function, in an attempt to identify the decomposition levels where the thresholding process must be more stringent and those where it can be more lenient, which increases its effectiveness in the removal of noisy coefficients. The proposed function and its variants demonstrate excellent results compared to other wavelet thresholding methods already described in the literature, including the famous Hard and Soft functions

HRTF interpolation in the wavelet transform domain

ABSTRACT This paper presents a new HRTF (Head Related Transfer Function) interpolation technique for three-dimensional sound generation. The proposed approach is based on the determination of the optimal weights to be applied to the HRTF coefficients of neighboring positions in the wavelet domain in order to obtain the HRTF at a given point. The proposed method is compared to conventional interpolation methods through the error analysis of the HRTFs in the frequency and time domains. It is verified that the proposed method presents smaller interpolation errors for all HRIRs (Head Related Impulse Responses) of an available database

Improving The Near-Perfect Hybrid Filter Bank Performance In The Presence Of Realization Errors

Hybrid filter banks have received increasing attention in the literature, for applications such as high-speed, high-resolution A/D and D/A converter design. In the manufacturing process, however, the filter coefficients of a hybrid filter bank are plagued with some errors due to technological limitations, particularly those of the analog filters, leading to degradation of the system performance. This work presents a novel method for improving the mean signal-to-noise-ratio of near-perfect reconstruction filter banks, taking into account such realization errors. The method consists in minimizing the total noise energy derived in an accurate way by a theoretical expression