S-transform is a new time-frequency analysis method, which is deduced from short-time Fourier transform and continue Wavelet transform. It has much better performance than traditional time-frequency method. Therefore, in this paper, the basic principle of is briefly introduced and the relationships between is analyzed by theoretical derivation. According to the simulation experiments, the time-...

Wavelets are being utilized in various communications applications either as an alternative to short time Fourier transform for spectral analysis of non-stationary data or as a new tool to bridge between time domain and frequency domain analysis. A wavelet-based algorithm for image compression with four levels of unequal error protection (UEP) codes over wide-band code division multiple access ...

Underwater acoustic images are captured by sonar technology which uses sound as a source. The noise in the may occur only during acquisition. These noises be multiplicative nature and cause serious effects on affecting their visual quality. Generally image denoising techniques that remove from can use linear non-linear filters. In this paper, wavelet based method is used to reduce images. decom...

Increasing requirements for the technical condition of machines induce the development of novel diagnostic methods for possible fault detection and identification in an early phase. Most of these methods are based on the processing of vibration signals. The classical methods often do not give full information about the actual condition of a machine. Therefore, it is necessary developing the app...

In this article, the empirical mode decomposition (EMD) is introduced to the problem of signal detection in underwater sound. EMD is a new method pioneered by Huang et al. for non-linear and nonstationary signal analysis. Based on the EMD, any input data can be decomposed into a small number of intrinsic mode functions (IMFs) which can serve as the basis of non-stationary data for they are comp...

In this paper we present a new methodology for computing a time-frequency map for non-stationary signals using the continuous wavelet transform (CWT). The conventional method of producing a time-frequency map using the Short Time Fourier Transform (STFT) limits the time-frequency resolution by a pre-defined window length. In contrast, the CWT method does not require pre-selecting a window lengt...