The problem of estimating the power spectra of non-stationary stochastic processes by using the harmonic wavelet transform is addressed in this paper. Conventional spectral analysis provides spectral coefficients that are averaged over time and thus, does not represent the evolutionary behavior of power spectra of non-stationary processes. In this study, evolutionary power spectrum of a non-sta...

Today wireless field is rapidly evolving. Due to the large number of standards, spectrum availability has become an important issue. In this context, an emerging technology, cognitive radio (CR) has been come out to solve this spectrum scarcity problem. The most important function of cognitive radio is spectrum sensing which requires more accuracy & low complexity. In this paper we analyze the ...

A method is proposed for classifying an observed non-stationary time series using a bias-corrected non-decimated wavelet transform. Wavelets are ideal for identifying highly discriminant local time and scale features. We view the observed signals as realizations of locally stationary wavelet (LSW) processes. The LSW model provides a time-scale decomposition of the signals under which we can def...

We propose a new method for simulating a Gaussian process, whose spectrum diverges at one or multiple frequencies in 0; 1 2 ] (not necessarily at zero). The method utilizes a generalization of the discrete wavelet transform, the discrete wavelet packet transform (DWPT), and only requires explicit knowledge of the spectral density function of the process { not its autocovariance sequence. An ort...

In the article comparison of time-frequency spectra of EMG signals obtained by the following methods: Fast Fourier Transform, predictive analysis and wavelet analysis is presented. The EMG spectra of biceps and triceps while an adult man was flexing his arm were analysed. The advantages of the predictive analysis were shown as far as averaging of the spectra and determining the main maxima are ...

Possibility of application of wavelet analysis in EPR spectroscopy is investigated. Basic mathematics of the method is summarized, with emphasis on the relation between EPR experiment and physical interpretation of wavelet transform. The fact that first derivative of the Lorentzian function can be used as a base wavelet is employed and the specific rules of the interpretation of the final wavel...

The methodology of vibration based condition monitoring technology has been developing at a rapid stage in the recent years suiting to the maintenance of sophisticated and complicated machines. The ability of wavelet analysis to efficiently detect non-stationary, non-periodic, transient features of the vibration signal makes it a demanding tool for condition monitoring. In this paper, the vibra...

The multi-scale Hermitian wavelet order envelope spectrum based bearing fault detection and diagnosis method under run-up condition is presented in this paper. This new approach based on the fusion of the computed order tracking, Hermitian wavelet transform and envelope spectrum is used for detection defects in roller element bearings. Firstly, Non-stationary vibration signal under run-up condi...

92, APC Road, Kolkata-700009, India [email protected], [email protected] Abstract— Most of the ECG analysing systems use explicit time plane features for cardiac pattern classification. This paper proposes a cross wavelet transform based method for Electrocardiogram signal analysis where parameters are identified from wavelet cross spectrum and wavelet cross coherence of ECG patterns. Applic...

In the developing world, the usage of Mobile phones and other data communication devices are unavoidable which results in the congestion of Spectrum. Recent studies have showed that nearly 70% of spectrum was unused most of the time. The band width becomes expensive due to shortage of frequencies. Therefore to use the spectrum effectively, we need to identify whether the spectrum is occupied or...