摘要 :
Coherent optical systems face two main categories of linear impairments, chromatic dispersion (CD) and polarization mode dispersion (PMD). Both CD and PMD will create large inter-symbol interference (ISI). This paper focuses on M-...
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Coherent optical systems face two main categories of linear impairments, chromatic dispersion (CD) and polarization mode dispersion (PMD). Both CD and PMD will create large inter-symbol interference (ISI). This paper focuses on M-quadrature amplitude modulation (QAM) signal detection directly using Echo State Networks (ESN) technique for compensating (residual CD and PMD) dispersion of coherent optical systems. The proposed approach can estimate directly the input sequence at the coherent receivers, without getting the electronic equalizer coefficients and estimating optical channel impulse response. In addition, the proposed approach can guarantee a convergence within a short data packet.
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摘要 :
Coherent optical systems face two main categories of linear impairments, chromatic dispersion (CD) and polarization mode dispersion (PMD). Both CD and PMD will create large inter-symbol interference (ISI). This paper focuses on M-...
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Coherent optical systems face two main categories of linear impairments, chromatic dispersion (CD) and polarization mode dispersion (PMD). Both CD and PMD will create large inter-symbol interference (ISI). This paper focuses on M-quadrature amplitude modulation (QAM) signal detection directly using Echo State Networks (ESN) technique for compensating (residual CD and PMD) dispersion of coherent optical systems. The proposed approach can estimate directly the input sequence at the coherent receivers, without getting the electronic equalizer coefficients and estimating optical channel impulse response. In addition, the proposed approach can guarantee a convergence within a short data packet.
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The results of investigation of stochastic features of an echo signal received by a high-resolution coherent radar are shown in the paper. The analytical relation between discrete model parameters of scattering and distribution la...
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The results of investigation of stochastic features of an echo signal received by a high-resolution coherent radar are shown in the paper. The analytical relation between discrete model parameters of scattering and distribution laws of received signal magnitude was established in this analysis. It was shown that the probability density function of signal magnitude depends on the scattering technique, in the general case essentially differs from the Rice-Rayleigh distribution. and cannot be written in explicit form. The proposed approach allows us to obtain analytically distribution functions which describe the stochastic features of scattered signal magnitude with good accuracy.
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A typical echo canceller uses an FIR adaptive filter to estimate the impulse response of the near-end echo path. However nonlinear echo components due to the loudspeaker and driving amplifier are not captured by such an arrangemen...
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A typical echo canceller uses an FIR adaptive filter to estimate the impulse response of the near-end echo path. However nonlinear echo components due to the loudspeaker and driving amplifier are not captured by such an arrangement. We propose a novel scheme for nonlinear acoustic echo cancellation where an accelerometer sensor captures loudspeaker vibration and this sensor signal is used along with the error signal to adapt the adaptive filter coefficients. The accelerometer sensor is used in lieu of explicit nonlinear modeling in the echo cancelling loop and hence it is compatible with typical NLMS and RLS echo cancellation algorithms. Experiments with an accelerometer mounted on the magnet of a hands-free kit show an echo reduction improvement by as much as 15 dB in situations of nonlinear loudspeaker distortion.
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A stochastic decomposition algorithm of the RF echo into its coherent and diffuse components is used towards estimating the structural parameters of the hyperplastic stages of the breast tissue leading to early breast cancer detec...
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A stochastic decomposition algorithm of the RF echo into its coherent and diffuse components is used towards estimating the structural parameters of the hyperplastic stages of the breast tissue leading to early breast cancer detection. The discrimination power of the various parameters is studied under a host of conditions such as varying resolution and SNR values using a point scatterer model simulator that mimics epithelium hyperplastic growth in the breast ducts. It is shown that three parameters, in particular, the number of coherent scatterers, the Rayleigh scattering degree and the energy of the diffuse scatterers, prove to show very high ability to discriminate between various stages of hyperplasia even in cases of low resolution and SNR values. Values of Az > 0.942 were obtained for resolution less than or equal to 0.4 mm even in low SNR values, then it drops below the 0.9 range as the resolution exceeds the 0.4 mm range.
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摘要 :
A stochastic decomposition algorithm of the RF echo into its coherent and diffuse components is used towards estimating the structural parameters of the hyperplastic stages of the breast tissue leading to early breast cancer detec...
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A stochastic decomposition algorithm of the RF echo into its coherent and diffuse components is used towards estimating the structural parameters of the hyperplastic stages of the breast tissue leading to early breast cancer detection. The discrimination power of the various parameters is studied under a host of conditions such as varying resolution and SNR values using a point scatterer model simulator that mimics epithelium hyperplastic growth in the breast ducts. It is shown that three parameters, in particular, the number of coherent scatterers, the Rayleigh scattering degree and the energy of the diffuse scatterers, prove to show very high ability to discriminate between various stages of hyperplasia even in cases of low resolution and SNR values. Values of Az > 0.942 were obtained for resolution less than or equal to 0.4 mm even in low SNR values, then it drops below the 0.9 range as the resolution exceeds the 0.4 mm range.
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In this paper, we study in depth the potential of detection of epithelium hyperplastic growth in the breast ducts leading to early breast cancer detection. Towards that end, we use a stochastic decomposition algorithm of the RF ec...
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In this paper, we study in depth the potential of detection of epithelium hyperplastic growth in the breast ducts leading to early breast cancer detection. Towards that end, we use a stochastic decomposition algorithm of the RF echo into its coherent and diffuse components that yields image parameters related to the structural parameters of the hyperplastic stages of the breast tissue. Previously, we proved that the two parameters, in particular the number of coherent scatterers and the Rayleigh scattering degree show very high ability to discriminate between various stages of hyperplasia even in cases of low resolution and low SNR values. In this paper, the discrimination power of the other parameters is studied further considering different depths using a point scatterer model simulator that mimics epithelium hyperplastic growth in the breast ducts. Significant improvement is obtained in the performance with the newly adopted method considering depth. Values of Az up to 0.974 are obtained when discriminating between pairs of stages using the parameter residual error variance. In addition, this paper presents a fast nonparametric segmentation procedure to locate the ducts illustrated using phantom data. The performance of the segmentation procedure is obtained as Az>0.948 for various regions of breast scans
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摘要 :
In this paper, we study in depth the potential of detection of epithelium hyperplastic growth in the breast ducts leading to early breast cancer detection. Towards that end, we use a stochastic decomposition algorithm of the RF ec...
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In this paper, we study in depth the potential of detection of epithelium hyperplastic growth in the breast ducts leading to early breast cancer detection. Towards that end, we use a stochastic decomposition algorithm of the RF echo into its coherent and diffuse components that yields image parameters related to the structural parameters of the hyperplastic stages of the breast tissue. Previously, we proved that the two parameters, in particular the number of coherent scatterers and the Rayleigh scattering degree show very high ability to discriminate between various stages of hyperplasia even in cases of low resolution and low SNR values. In this paper, the discrimination power of the other parameters is studied further considering different depths using a point scatterer model simulator that mimics epithelium hyperplastic growth in the breast ducts. Significant improvement is obtained in the performance with the newly adopted method considering depth. Values of Az up to 0.974 are obtained when discriminating between pairs of stages using the parameter residual error variance. In addition, this paper presents a fast nonparametric segmentation procedure to locate the ducts illustrated using phantom data. The performance of the segmentation procedure is obtained as Az>0.948 for various regions of breast scans
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This paper describes a processing algorithm based on polynomial phase modeling scheme that increases visibility of maneuvering targets in HF over-the-horizon radar (OTHR). For the presence of the echo backscattered by the target t...
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This paper describes a processing algorithm based on polynomial phase modeling scheme that increases visibility of maneuvering targets in HF over-the-horizon radar (OTHR). For the presence of the echo backscattered by the target that has significantly varying radial velocity within a coherent integration time (CIT), it is difficult for traditional coherent processing to centralize energy and peak in Doppler spectrum. Due to the polynomial property of the phase of maneuvering target radar echo, a polynomial phase signal (PPS) is introduced to model the complex Doppler variation of maneuvering targets. As an effective method to estimate the parameters of PPS, a high-order ambiguity function (HAF) based algorithm is applied. And a compensation process follows to eliminate the coherent processing loss (CIL) caused by irregular motion of targets. The experimental results are given to illustrate the validity and efficiency of the proposed method.
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摘要 :
This paper describes a processing algorithm based on polynomial phase modeling scheme that increases visibility of maneuvering targets in HF over-the-horizon radar (OTHR). For the presence of the echo backscattered by the target t...
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This paper describes a processing algorithm based on polynomial phase modeling scheme that increases visibility of maneuvering targets in HF over-the-horizon radar (OTHR). For the presence of the echo backscattered by the target that has significantly varying radial velocity within a coherent integration time (CIT), it is difficult for traditional coherent processing to centralize energy and peak in Doppler spectrum. Due to the polynomial property of the phase of maneuvering target radar echo, a polynomial phase signal (PPS) is introduced to model the complex Doppler variation of maneuvering targets. As an effective method to estimate the parameters of PPS, a high-order ambiguity function (HAF) based algorithm is applied. And a compensation process follows to eliminate the coherent processing loss (CIL) caused by irregular motion of targets. The experimental results are given to illustrate the validity and efficiency of the proposed method.
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