Papers by Keyword: Wigner-Ville Distribution (WVD)

Abstract: Based on fractional Fourier transformation (FRFT), the feature of the signals which vary smoothly from time domain to frequency domain is given. The FRFT method is applied to the estimation and detection of nonlinear frequency modulated signals to which piecewise linearly approach. Wigner-Ville time frequency distribution of the signals is used after approaching and the masking results of the original signal accumulate energy as detecting statistic. A signal detector based on energy accumulation from time frequency domain in the angle of analysis of both time and frequency is proposed. Finally, a comparison with traditional non-coherent energy accumulation methods is made, which shows the proposed method has superior performance.

Abstract: The fractional Fourier transform (FRFT) is a generalization of the Fourier transform. The article first introduces the definition of FRFT transformation; then analyzed FRFT Chirp signal based on this humble proposed restoration Chirp signal in a noisy background in two ways: one is based on parameter estimation, and the other is based on the scores Fourier domain filtering to achieve signal reconstruction; Finally, simulation verify the feasibility of the above analysis.

Abstract: Based on the relationship between the Radon-Wigner transform and fractional Fourier transform and the time frequency distribution, using the property that Radon-Wigner transform has better performance in time and frequency domain, detection and parameter estimation of Chirp signal have been done by Radon-Wigner transform or fractiona1 Fourier transform. The theoretica1 analysis and simulation prove that two techniques are better than generic time-frequency transform, such as Wigner-Ville transform.

Abstract: The deformation analysis of explosion vessel is very important in strength analysis and engineering design. By means of laser Doppler measurement and Wigner-Ville distribution, the expansion process of steel explosion vessels has been studied, and the frequency characteristics of the strain wave are analyzed. Finally, the experimental results of deformation and vibration frequency of vessel are given under the condition of 300g TNT explosion equivalent.

Abstract: It is well known that adaptive Gaussian chirplet signal decomposition algorithm has the best time frequency resolution in all signal decomposition algorithms. It is widely used in non linear and non stationary signal decomposition, especially for the signal which is superposition of chirplet functions decomposition. But it has a large amount of computation. In this paper, we propose a fast algorithm based on short time Fourier transform (STFT) method and we change parameters’ domain. Using this fast algorithm to decompose a four atoms non-linear signal computes very fast and it can also avoid the cross term’s interferer of the Wigner-Ville distribution.

Abstract: Time-frequency analysis is a powerful tool for analyzing non-stationary signals, which can describe the signals frequency varying with time and provide us the joint information of time domain and frequency domain of the signal. We use a synthetic signal to realize the time-frequency analysis methods of wavelet transform, S transform and Wigner-Ville distribution. Through comparing and analyzing those time-frequency distributions, we propose a new method of integrating wavelet transform and Wigner-Ville distribution. This new method gives a better result than that of wavelet transform and Wigner-Ville distribution and increases the time-frequency resolution.

Abstract: Hilbert-Huang Transform (HHT) Spectrum is analyzed, and is compared with Wigner-Ville distribution(WVD). And it is proposed a method that is “band pass filtering --signal purification and reconstruction --HHT spectrum analyses” method to carry on the state recognition and fault diagnosis of the mechanical equipment. The compared signals include: the signals of harmonic, amplitude modulation and frequency modulation, and the mixed signals that are composed of these single signal, then it is pointed out: HHT Spectrum have higher frequency resolution than WVD, and it has overcome the latter influence of cross-term interference. At last, real signals of fault gear are analyzed by this method, and it is indicated that the method can offer a new and effective method for fault diagnosis and condition monitoring.

Abstract: The high accuracy time-frequency representation of non-stationary signals is one of the key researches in seismic signal analysis. Low-frequency part of the seismic data often has a higher frequency resolution, on the contrary it tends to have lower frequency resolution in the high frequency part. It’s difficult to fine characterize the time-frequency variation of non-stationary seismic signals by conventional time-frequency analysis methods due to the limitation of the window function. Therefore based on the Ricker wavelet, we put forward the matching pursuit seismic trace decomposition method. It decomposes the seismic records into a series of single component atoms with different centre time, dominant frequency and energy, by making use of the Wigner-Ville distribution, has the time-frequency resolution of seismic signal reach the limiting resolution of the uncertainty principle and skillfully avoid the impact of interference terms in conventional Wigner-Ville distribution.

Abstract: In this paper, a time-frequency analytic system is implemented by using mixed programming of Matlab and Delphi languages based on COM (Component Object Model）module technology. Matlab possesses many signal analytic functions and Delphi has a friendly visual programming environment. These two advantages are fully combined in the mixed programming. This system can be easily upgraded to expand new analytic functions with help of COM module technology. Fault diagnosis of a grinding machine is carried out by using this system. A same vibrational signal sampled from the machine is analyzed in turn by three methods in this system that are Fast Fourier Transform(FFT), Wigner-Ville Distribution(WVD) and Choi-Williams Distribution(CWD). Comparing with the three results, it shows that CWD can get best diagnostic information and validity of the estimation on the instantaneous frequency of a signal. Success of the mixed programming is presented meantime.

Abstract: Chirp signal is a typical non-stationary signal, and have been widely used in communication, sonar, radar and so on. So, this signal is worth to analysis. In order to show the characteristics, this paper first introduces the definition and formula of each algorithm, then with all kinds of time-frequency analysis method to the signals, and the signal to add two sine signal noise are analyzed, the comparison of the characteristics of the method in the paper, and the signal for the analysis, the selection of an appropriate analysis. Through analysis and comparison, when dealing with the signal, Hilbert-Huang transformation not only has a better gathered characteristic, but also has a better resolution to distinguish the sine signal noise. Finally, use the MATLAB software simulation to obtain the result.