Showing papers on "Reassignment method published in 2015"
TL;DR: Two new post-transformations for the short-time Fourier transform that achieve a compact time-frequency representation while allowing for the separation and the reconstruction of the modes are introduced.
Abstract: This paper considers the analysis of multicomponent signals, defined as superpositions of real or complex modulated waves. It introduces two new post-transformations for the short-time Fourier transform that achieve a compact time-frequency representation while allowing for the separation and the reconstruction of the modes. These two new transformations thus benefit from both the synchrosqueezing transform (which allows for reconstruction) and the reassignment method (which achieves a compact time-frequency representation). Numerical experiments on real and synthetic signals demonstrate the efficiency of these new transformations, and illustrate their differences.
345 citations
TL;DR: Findings reveal the effectiveness of the method as competent against the other baselines, especially for A2-P2 overlaps and low energy P2, and its robustness by defining split detectability (SDT), the split detection aptness through detecting P2s, by measuring up to 96 percent.
Abstract: This study proposes a quantitative measurement of split of the second heart sound (S2) based on nonstationary signal decomposition to deal with overlaps and energy modeling of the subcomponents of S2. The second heart sound includes aortic (A2) and pulmonic (P2) closure sounds. However, the split detection is obscured due to A2-P2 overlap and low energy of P2. To identify such split, HVD method is used to decompose the S2 into a number of components while preserving the phase information. Further, A2s and P2s are localized using smoothed pseudo Wigner-Ville distribution followed by reassignment method. Finally, the split is calculated by taking the differences between the means of time indices of A2s and P2s. Experiments on total 33 clips of S2 signals are performed for evaluation of the method. The mean ± standard deviation of the split is 34.7 ± 4.6 ms. The method measures the split efficiently, even when A2-P2 overlap is ≤ 20 ms and the normalized peak temporal ratio of P2 to A2 is low (≥ 0.22). This proposed method thus, demonstrates its robustness by defining split detectability (SDT), the split detection aptness through detecting P2s, by measuring upto 96 percent. Such findings reveal the effectiveness of the method as competent against the other baselines, especially for A2-P2 overlaps and low energy P2.
31 citations
TL;DR: The analysis results show that the proposed interference detection technique effectively overcomes the cross-terms problem and also preserves good TF localization properties, which has been proven to be effective and valid to enhance the interference detection performance of the GNSS receivers, particularly in the jamming environments.
Abstract: In this paper, an improved joint time-frequency (TF) analysis method based on a reassigned smoothed pseudo Wigner–Ville distribution (RSPWVD) has been proposed in interference detection for Global Navigation Satellite System (GNSS) receivers. In the RSPWVD, the two-dimensional low-pass filtering smoothing function is introduced to eliminate the cross-terms present in the quadratic TF distribution, and at the same time, the reassignment method is adopted to improve the TF concentration properties of the auto-terms of the signal components. This proposed interference detection method is evaluated by experiments on GPS L1 signals in the disturbing scenarios compared to the state-of-the-art interference detection approaches. The analysis results show that the proposed interference detection technique effectively overcomes the cross-terms problem and also preserves good TF localization properties, which has been proven to be effective and valid to enhance the interference detection performance of the GNSS receivers, particularly in the jamming environments.
30 citations
TL;DR: In this paper, a time-varying optimal window width (TVOWW) selection scheme was proposed to optimize the performance of several nonlinear-type time-frequency analyses, including the reassignment method, and the synchrosqueezing transform (SST) and its variations.
Abstract: We propose a time-varying optimal window width (TVOWW) selection scheme to optimize the performance of several nonlinear-type time-frequency analyses, including the reassignment method, and the synchrosqueezing transform (SST) and its variations A window rendering the most concentrated distribution in the time-frequency representation (TFR) is regarded as the optimal window The TVOWW selection scheme is particularly useful for signals that comprise fast-varying instantaneous frequencies and small spectral gaps To demonstrate the efficacy of the method, in addition to analyzing a synthetic signal, we study an atomic time-varying dipole moment driven by two-color mid-infrared laser fields in attosecond physics
17 citations
TL;DR: The photon reassignment method for MMM, established based on the maximum likelihood (ML) estimation, is presented for quantification of crosstalk between the anodes of MAPMT without a priori measurement and provides the reassignment of the photons generated by the ghost images to the original spatial location thus increases the SNR of the final reconstructed image.
Abstract: Multifocal multiphoton microscopy (MMM) achieves fast imaging by simultaneously scanning multiple foci across different regions of specimen. The use of imaging detectors in MMM, such as CCD or CMOS, results in degradation of image signal-to-noise-ratio (SNR) due to the scattering of emitted photons. SNR can be partly recovered using multianode photomultiplier tubes (MAPMT). In this design, however, emission photons scattered to neighbor anodes are encoded by the foci scan location resulting in ghost images. The crosstalk between different anodes is currently measured a priori, which is cumbersome as it depends specimen properties. Here, we present the photon reassignment method for MMM, established based on the maximum likelihood (ML) estimation, for quantification of crosstalk between the anodes of MAPMT without a priori measurement. The method provides the reassignment of the photons generated by the ghost images to the original spatial location thus increases the SNR of the final reconstructed image.
14 citations
TL;DR: The analysis results show that the proposed interference detection technique effectively overcomes the cross-term problem and also keeps good TF localization properties, which has been proven to be valid and effective to enhance the interference detection performance.
Abstract: Interference detection is very important for Global Navigation Satellite System (GNSS) receivers. Current work on interference detection in GNSS receivers has mainly focused on time-frequency (TF) analysis techniques, such as spectrogram and Wigner–Ville distribution (WVD), where the spectrogram approach presents the TF resolution trade-off problem, since the analysis window is used, and the WVD method suffers from the very serious cross-term problem, due to its quadratic TF distribution nature. In order to solve the cross-term problem and to preserve good TF resolution in the TF plane at the same time, in this paper, a new TF distribution by using a reassigned spectrogram has been proposed in interference detection for GNSS receivers. This proposed reassigned spectrogram method efficiently combines the elimination of the cross-term provided by the spectrogram itself according to its inherent nature and the improvement of the TF aggregation property achieved by the reassignment method. Moreover, a notch filter has been adopted in interference mitigation for GNSS receivers, where receiver operating characteristics (ROCs) are used as metrics for the characterization of interference mitigation performance. The proposed interference detection method by using a reassigned spectrogram is evaluated by experiments on GPS L1 signals in the disturbing scenarios in comparison to the state-of-the-art TF analysis approaches. The analysis results show that the proposed interference detection technique effectively overcomes the cross-term problem and also keeps good TF localization properties, which has been proven to be valid and effective to enhance the interference detection performance; in addition, the adoption of the notch filter in interference mitigation has shown a significant acquisition performance improvement in terms of ROC curves for GNSS receivers in jamming environments.
11 citations
TL;DR: In this paper, the reassignment method is proposed as an improved signal analysis technique to address the deficiencies of classical time-frequency analysis, which may lead to inaccurate detection and parameter extraction.
Abstract: Digital intercept receivers are currently moving towards classical time-frequency analysis techniques for analyzing low probability of intercept radar signals. Although these techniques are an improvement over existing Fourier-based techniques, they still suffer from a lack of readability, due to poor time-frequency localization and cross-term interference, which may lead to inaccurate detection and parameter extraction. In this study, the reassignment method, because of its ability to smooth out cross-term interference and improve time-frequency localization, is proposed as an improved signal analysis technique to address these deficiencies. Simulations are presented that compare time-frequency representations of the classical time-frequency techniques with those of the reassignment method. Four different low probability of intercept waveforms are analyzed (two frequency modulated continuous wave waveforms and two frequency shift keying waveforms). The following metrics are used for analysis evaluation: Percent detection, number of cross-term false positives, lowest signal-to-noise ratio for signal detection, processing time, percent error of: Carrier frequency, modulation bandwidth, modulation period, time-frequency localization (x and y direction) and chirp rate. Experimental results demonstrate that the ‘squeezing’ and ‘smoothing’ qualities of the reassignment method improve readability over the classical time-frequency analysis techniques and consequently, provide more accurate signal detection and parameter extraction in all but one of the metrics categories.
5 citations
TL;DR: In this paper, the combination of the synchrosqueezing transform and Lempel-Ziv complexity method is used for feature extraction and recognition of gear system faults. But the complexity values are not dependent on the magnitude of the measured signal, the proposed method is less sensitive to the data sets measured under different data acquisition conditions.
Abstract: The Synchrosqueezing is a special case of the reassignment method and concentrates the time-frequency representation (TFR) in a scale dimension. Compared to other TFR enhancement methods, the synchrosqueezing offers better adaptability, less deformation for IF profile and an exact reconstruction formula for constituent components. This paper deals with the investigation of descriptors based on the combination of the synchrosqueezing transform (SST) and Lempel-Ziv complexity methods. This last one transforms the analyzed signal into a data sequence. In the first part, the vibration signal components are extracted by using the synchrosqueezing transform and the reconstruction method. Afterward, the Lempel-Ziv complexity values are calculated. Since the complexity values are not dependent on the magnitude of the measured signal, the proposed method is less sensitive to the data sets measured under different data acquisition conditions. This approach is applied for monitoring and diagnosing the defects during a fatigue test on a first gear reducer and also when varying the load on a second gear reducer by using the recorded vibration signals. It can also provide a new way for feature extraction and recognition of gear system faults.
3 citations
10 Aug 2015
TL;DR: Evaluation results indicate that the quasi-dynamic inter-satellite link (ISL) reassignment method can obtain invariable and longer snapshot duration, which is superior to the natural partition method.
Abstract: This paper presents a quasi-dynamic inter-satellite link (ISL) reassignment method to optimize the snapshot routing performance for LEO (low Earth orbit) satellite networks. When the snapshot routing tables are switching in all satellites, we propose to reassign the inter-plane ISLs regularly to improve the quality of the next snapshot. Evaluation results indicate that our method can obtain invariable and longer snapshot duration, which is superior to the natural partition method. Meanwhile, compared with the equal partition method, the proposed method can averagely increase 5.95 % on-board transceiver utility ratio. We believe that our method could be practically and effectively applied in future LEO satellite networks.
1 citations
Posted Content•
TL;DR: The reassignment method for the wavelet transform is investigated in this paper, and good results are obtained if the wavelets is an extremal for the uncertainty relation of the affine group.
Abstract: The reassignment method for the wavelet transform is investigated. Particularly good results are obtained if the wavelet is an extremal for the uncertainty relation of the affine group.
1 citations
TL;DR: The reassigned local polynomial periodogram along the frequency direction (RfLPP) is shown to be able to perfectly localize the chirp signal, and is combined with the Hough transform for chirP signal detection in the parameter domain.
Abstract: In this paper, the reassigned local polynomial periodogram along the frequency direction (RfLPP) is shown to be able to perfectly localize the chirp signal. Due to this property, the RfLPP is combined with the Hough transform for chirp signal detection in the parameter domain. Simulations of the RfLPP-Hough transform are given for chirp signal detection in white Gaussian noise and impulsive noise, with comparisons to the pseudo-Wigner-Hough transform (PWHT), the local polynomial periodogram (LPP)-Hough transform (LHT), and the reassigned LPP-Hough transform. It shows that the RfLPP-Hough transform can provide better performance with reduced computation time and is a proper candidate for chirp signal detection.
01 Jan 2015
16 Mar 2015
TL;DR: A robust environmental sound classification approach, based on reassigned spectrogram and log-Gabor filters, is presented, which produces an average classification accuracy of the order 91.77%.
Abstract: We present a robust environmental sound classification approach, based on reassigned spectrogram and log-Gabor filters. In this method, reassigned spectrograms are passed through an appropriate log-Gabor filter and the outputs are underwent an optimal feature selection procedure based on mutual information criteria. The evaluation of this classification system is performed on a corpus of 6 environmental sounds classes. The best performance was obtained using multi-class support vector machines (SVM's), producing an average classification accuracy of the order 91.77%.