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Viterbi algorithm (VA) applied to time frequency (TF) distribution is a highly performed instantaneous frequency (IF) estimator, but it suffers from switch problem (SP) at the intersected points of multi-components on the TF plane. In order to suppress the SP in VA, an improved VA (IVA) in this paper assumes the IF variation trends between two adjacent IF points are not large, then a new penalty function...
A joint timing offset (TO) and frequency offset (FO) estimation method based on Radon-Wigner transform (RWT) is first proposed for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. The result shows that the timing and frequency synchronization performance of the proposed method are both better than the Schmidl & Cox method and fractional Fourier transform (FrFT) algorithm...
Linear frequency modulated continuous wave (LFMCW) signal has been widely used in the new system radar as the progress of radar technology. It is difficult to estimate the parameters of the LFMCW signal under noncooperative circumstances. In this paper, we introduce the time frequency analysis methods to signal representation and parameter estimation. The S-Method with adaptive window is proposed...
In the presence of environmental noise, speaker verification systems inevitably see a decrease in performance. This paper proposes the (1) use of two parallel classifiers, (2) feature enhancement based on blind signal-to-noise ratio (SNR) estimation and (3) fusion, to improve the performance of speaker verification systems. The two classifiers are based on Gaussian mixture models and the partial least-squares...
Khatri-Rao (KR) product increases the number of elements virtually and enables to estimate more incoming waves in direction-of-arrival (DOA) estimation using array antenna. The DOA estimation with the KR scheme, however, makes the estimation difficult because the scheme makes the data coherent. The sparse signal reconstruction is a method realizing the DOA estimation regardless of the signal correlation...
For wireless remote access security, forensics, electronic commerce and surveillance applications, there is a growing need for biometric speaker identification systems to be robust to noise. This paper examines the robustness issue for the case of additive white noise at signal to noise ratios ranging from 0 to 30 dB. A Gaussian mixture model classifier based on adaptation of a universal background...
There is a tiny difference between the main peak and side peaks after the traditional quadratic correlation calculation in the time-delay estimation of passive acoustic positioning system. It is easy to lead to a wrong peak value when the system resolution is low or mutations caused by noises occur near the side peaks. In order to weaken the influence of the quadratic correlation side peaks, the method...
The work described herein discusses the application of generalized cross-correlation method to time delay estimation of infrasound signal. At present, the basic cross-correlation technique is mainly used to the time delay estimation of infrasound signal. However, the estimation accuracy based on this method is not high. In order to improve the accuracy, the generalized cross-correlation method is...
Compressive Sensing (CS) has been widely investigated in the Cognitive Radio (CR) literature in order to reduce the hardware cost of sensing wideband signals assuming prior knowledge of the sparsity pattern. However, the sparsity order of the channel occupancy is time-varying and the sampling rate of the CS receiver needs to be adjusted based on its value in order to fully exploit the potential of...
Estimating the Signal to Noise Ratio (SNR) of the Primary Users' (PUs) signals over a wideband spectrum accurately is crucial in order to fully exploit an under-utilized primary spectrum using underlay Cognitive Radio (CR) techniques. In this context, we study an SNR estimation problem for a wideband CR under practical correlated scenarios in compressive settings. We carry out detailed theoretical...
It is important to estimate the multipath time delay in underwater communication and target positioning. Based on the good time delay resolution, wideband signal is used to estimate time delay conventionally, in some situation, it is hard to use wideband signals. Focused on the narrowband signal multipath time delay estimating, an algorithm based on spectral subtraction in logarithm domain was proposed...
Accurately detecting cellular structures in fluorescence microscopy is of primary interest for further quantitative analysis such as counting, tracking or classification. We aim at segmenting vesicles in TIRF images. The optimal segmentation scale is automatically selected, relying on a multiscale feature detection stage, and the segmentation consists in thresholding the Laplacian of Gaussian of the...
In addition to spectrum sensing capability required by a Cognitive Radio (CR), Signal to Noise Ratio (SNR) estimation of the primary signals is crucial in order to adapt its coverage area dynamically using underlay techniques. Furthermore, in practical scenarios, the fading channel may be correlated due to various causes such as insufficient scattering in the propagation path and antenna mutual coupling...
The linear minimum mean-square error (LMMSE) estimation has been shown to provide a good tradeoff between the computational requirement and estimation accuracy in nonlinear point estimation. However, the best estimator within the linear class may not be adequate to provide acceptable accuracy when dealing with a highly nonlinear problem. A generalized LMMSE (GLMMSE) estimation framework searches for...
A well known computationally efficient method for parameters estimation of linear frequency modulated (LFM) signals is to mix the received signals with a shifted version of itself. The drawback is the dominating cross terms in low signal to noise ratio scenarios. In this paper we present a novel technique for the detection/estimation of a weak LFM signal using an array of receivers which can strongly...
The commonly used principal component analysis (PCA) assumes circular Gaussian distribution for the observed complex random variables. This paper extends PCA to the general case where the signals can be noncircular, and introduces a new PCA method called the noncircular PCA (ncPCA). We study the properties of ncPCA and propose an efficient algorithm for its implementation. Numerical results are presented...
Pulse Doppler (PD) radar system with monopulse estimation can effectively acquire the location information of weak target, since it combines the advantages of coherent integration and monopulse technique. However, as it takes some time to realize the coherent integration, target motion will result in the decline of integration efficiency, thus affects the angle measurement precision. This paper investigates...
The performance of the blind symbol rate detection through non-linearity degrades under some conditions, including small excess bandwidth, limited symbol length and low signal-to-noise ratio. The improved algorithm here considers the main disturbance-continuous part of the power spectral of non-linearity as its envelope layer and eliminates it by an envelope sifting process, thus greatly improve the...
In this paper, we are interested in the problem of parameter estimation of 3-order polynomial phase signals (PPS) affected by additive Gaussian white noise. A new algorithm for 3-order PPS parameter estimation is proposed. Filter bank, short time Radon-Wigner transform, cure fitting and local scope searching algorithm is adopt together to get the parameter's accurate estimation. The merit of this...
The Wigner-Ville Hough transform (WVHT) has been applied to detect and estimate the parameters of linear frequency-modulated continuous-wave (LFMCW) low probability of intercept (LPI) radar waveforms. The WVHT, which is optimal for a single linear frequency modulated (LFM) signal, becomes sub-optimal when applied to LFMCW signals since the observed waveform is composed of concatenated LFM pulses....
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