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Statistical Signal and Array Processing, 1992. Conference Proceedings., IEEE Sixth SP Workshop on

Date 7-9 Oct. 1992

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Displaying Results 1 - 25 of 127
  • IEEE Sixth SP Workshop on Statistical Signal and Array Processing Conference Proceedings (Cat. No.92TH0410-1)

    Publication Year: 1992
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    Freely Available from IEEE
  • A unitary transformation algorithm for wideband array processing

    Publication Year: 1992 , Page(s): 300 - 303
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    The authors apply a two-sided transformation on the cross-correlation matrices of the array. It is shown that the two-sided correlation transformation (TCT) generates unbiased estimates of the directions of arrival regardless of the bandwidth of the signals. The capability of the method for resolving two closely spaced sources is compared with that of the coherent signal-subspace method. The resolution threshold for the new technique is smaller View full abstract»

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  • The effect of normalization and quantization on long-term spectral integration

    Publication Year: 1992 , Page(s): 229 - 234
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    It is found that performance loss due to the normalization is small, less than 0.2 dB for an example. The loss due to quantization depends on the number of bits used. For one-bit (two-level) quantization, the loss is approximately 1 dB. This can be reduced to less than 0.1 dB by the use of three bits (8 levels) in the quantizer View full abstract»

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  • Simultaneous CFAR detection and frequency estimation of a sinusoidal signal in noise

    Publication Year: 1992 , Page(s): 78 - 81
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    A periodogram-based method is presented for simultaneously detecting and estimating an unknown sinusoidal signal. For additive white Gaussian noise, the scheme can achieve constant-false-alarm-rate detection and provide the maximum likelihood frequency estimate. For more general colored noise, the detection performance is derived approximately, and some numerical examples show that the scheme can nominally maintain the CFAR property, thus exhibiting some degree of robustness. It can be implemented easily by VLSI hardware and is suited to real-time applications View full abstract»

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  • Performance analysis of eigenstructure based DOA estimators employing conjugate symmetric beamformers

    Publication Year: 1992 , Page(s): 384 - 387
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    If one employs conjugate centro-symmetric beamforming weight vectors in conjunction with a uniformly-spaced linear array, the noise eigenvectors in Beamspace MUSIC may be computed as the `smallest' eigenvectors of the real part of the beamspace sample covariance matrix. Through theoretical performance analysis and verification via Monte Carlo simulations, this paper shows that taking the real part offers significant performance gains in addition to computational gains, particularly for correlated sources View full abstract»

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  • Optimal transforms related to path in the time-frequency plane

    Publication Year: 1992 , Page(s): 34 - 37
    Cited by:  Papers (1)
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    This paper shows how to construct integral operators adapted to a given time-frequency energy distribution. The phase function, which is an extension of the phase ωt of the classical Fourier transform, makes it possible to construct an integral operator. The transform is adapted when the partial derivative ∂φ/∂t is the instantaneous frequency of the signal View full abstract»

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  • Detection and recovery of a narrow-band signal in severely nonstationary noise

    Publication Year: 1992 , Page(s): 296 - 299
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    The authors view the interference as a stochastic process n (m,t) in two variables. They assume a uniform linear array that the carrier frequency is known and that the direction of arrival of the desired signal does not change. The approach is an application/extension of the multi-window method for spectrum estimation and harmonic analysis introduced by Thomson (Proc. IEEE vol.70, no.9, p.1055-96, Sept.1982). How the signal is estimated if present, and how to estimate the DOA, are discussed briefly View full abstract»

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  • Comparison of AIC and MDL to the minimum probability of error criterion

    Publication Year: 1992 , Page(s): 114 - 117
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    A large variety of model order determination problems involve testing the eigenvalue of a sample covariance matrix to estimate how many of the smallest eigenvalues of the true covariance matrix are equal. Using the theory of multiple hypothesis tests, the author derives the minimum probability of error criterion that is similar to AIC and MDL and is implemented in exactly the same manner, but is designed to minimize the probability of choosing the wrong model order. The basic structure of this test is very similar except for an extra term that increases adaptability and enables this criterion to outperform both AIC and MDL View full abstract»

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  • Frequency-wavenumber spectrum analysis using quadratic estimators

    Publication Year: 1992 , Page(s): 416 - 419
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A general representation for all non-negative, modulation invariant estimators of the frequency-wavenumber spectrum shows explicitly how the quadratic estimates are constructed from linear transformations of the array data. The windows associated with these transformations are those normally associated with `classical' spectrum estimators. The authors present closed form representations for the moments of quadratic estimators, and show that variance decreases as the number of orthogonal windows increases. Since a time-bandwidth product bounds the number of orthogonal windows with given selectivity, the design process involves the classical issue of trading resolution and variance. With this issue in mind, the development of both separable and inseparable windows is considered View full abstract»

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  • Identification of nonminimum phase rational systems

    Publication Year: 1992 , Page(s): 408 - 411
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    This paper addresses the problem of identifying such systems from partial information regarding their output autocorrelation and impulse response sequences. Since autocorrelation sequences can identify systems only up to their minimum phase counterparts, by employing portions of the impulse response, it exhibits closed form solutions in the rational instance that match the given data View full abstract»

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  • Linear prediction based on higher order statistics by a new criterion

    Publication Year: 1992 , Page(s): 148 - 151
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    This criterion requires only partial Mth-order cumulants CM,e(0,k1, k1, . . ., kM/2-1, k M /2-1) of the prediction error e(k ) where M is even. Theoretically, it is shown that the proposed filter associated with a stationary process x(k ) is the same as the conventional correlation based (minimum-phase) LPE filter associated with the nonGaussian signal y(k) (noise-free). Simulation results show that when y(k) is an autoregressive process of known order, the proposed filter works well View full abstract»

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  • On the performance of cumulant-based detection of nonGaussian signals

    Publication Year: 1992 , Page(s): 173 - 176
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    Detection of a non-Gaussian signal in additive Gaussian noise is assumed to be done in two steps. A selected set of sample cumulants and/or moments of the data are computed; next a detection statistic based on these sample moments/cumulants is evaluated. The paper outlines the asymptotic performance analysis of this detector for a fairly general class of signal and noise models. A simple example is worked out in detail View full abstract»

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  • Practical detection with calibrated arrays

    Publication Year: 1992 , Page(s): 82 - 85
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    This paper discusses some of the practical limitations of detection methods formulated in terms of the eigenvalues of the sample covariance matrix of the output of a sensor array. It presents an approach based on the principal eigenvectors and the measured array manifold that appears to be at least as sensitive, but apparently much more robust than methods such as AIC and MDL. Comparative performance results are given for simulation data with a variety of noise statistics and for data obtained from an experimental array View full abstract»

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  • Efficient estimation of 2-dimensional frequencies of sinusoids by the annihilator method and constrained total least squares

    Publication Year: 1992 , Page(s): 388 - 391
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    The authors address the problem of estimating the 2-dimensional frequencies from a set of double indexed samples consisting of unknown linear combinations with efficiency. These problems arise in high resolution radar/sonar imaging, array signal processing and nuclear magnetic resonance imaging. A new approach is based on the annihilator method and a generalization of the CTLS technique. Simulation results show that this approach can estimate the 2-D frequencies with accuracies approaching the Cramer-Rao bound even when the separation of the sinusoids is a fraction of the discrete Fourier transform resolution bin View full abstract»

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  • Geometry of the Cramer-Rao bound

    Publication Year: 1992 , Page(s): 5 - 8
    Cited by:  Papers (4)
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    The Fisher information matrix determines how much information is given by a measurement about the parameters that index the underlying probability distribution. This paper assumes that the parameters structure the mean value vector in a multivariate normal distribution. The Fisher matrix is then a Gramian constructed from the sensitivity vectors that characterize the first-order variation in the mean with respect to the parameters. The inverse of the Fisher matrix has several geometrical properties that bring insight into the problem of identifying multiple parameters. The angle between a given sensitivity vector and the linear subspace spanned by all others determines the variance bound for identifying a given parameter. Similarly, the covariance for identifying the linear influence of two different subsets of parameters depends on the principal angles between the linear subspaces spanned by the sensitivity vectors for the respective subsets View full abstract»

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  • Wavelet decomposition of event related potentials: toward the definition of biologically natural components

    Publication Year: 1992 , Page(s): 38 - 41
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    Transient time-voltage neural waveforms recorded at the scalp are elicited by discrete sensory or perceptual events and thought to be composed of fundamental waveform components. A new definition is proposed of ERP components as `wavepackets', which are oscillating waveforms that extend throughout the ERP. The wavelet transform is used to extract orthogonal wavepacket components. Each component is restricted to its own frequency band, and may strongly influence the ERPs over local time regions. Unilateral visual field stimulation data from human subjects show that wavepacket components reveal visual processing events earlier than direct amplitude measurements on the ERPs. Wavepackets provide new insights into ERP morphology and its relationship to the timecourse of neural processes View full abstract»

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  • A generalized AR operator for non-uniform noise compensation in DOA signal enhancement

    Publication Year: 1992 , Page(s): 292 - 295
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    In some DOA applications, the M sensors of the array can be affected by spatially uncorrelated white noise having power levels different from sensor to sensor. Such a noise power unbalance induces severe bias errors of DOA estimates performed by eigenspace based methods. In some instances, an estimate of the ratio between the noise variances of the sensors is available, so that a noise pre-compensation procedure can be conceived. For this purpose, a generalized AR estimator is considered in connection with the signal enhancement approach. Simulation examples illustrate the method View full abstract»

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  • Signal detection by detecting departure from noise

    Publication Year: 1992 , Page(s): 118 - 121
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    The short term sample spectrum is examined to determine if the sample spectrum is noise-like. The parameters measured are nonparametric and include the sample coefficient of variation, the center frequency, the bandwidth, and higher order measures of the spectrum. For a typical application in a voice grade channel, the performance of the detector is orders of magnitude better than the usual adaptive short term energy threshold detectors. The time between false alarms goes from minutes to days for a given detection probability. The detection is independent of the signal amplitude. There are no adaptive thresholds requiring signal history for operation. Signals may be detected in a very short time after the analysis is begun, the time required to accumulate enough samples to form one sample spectrum View full abstract»

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  • Study of the cepstral coefficient probability density function

    Publication Year: 1992 , Page(s): 440 - 443
    Cited by:  Papers (1)
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    Cepstral coefficients, used in pattern recognition and classification with the k-nearest-neighbor method, give far better results than classification with the centroid distance rule. This paper proposes an analysis of cepstral coefficient probability density which reveals why the k-NN rule is in many instances a necessary tool in this particular representation space View full abstract»

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  • A fundamental algorithm for the power estimation of closely separated spectral sources

    Publication Year: 1992 , Page(s): 420 - 423
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    A new algorithm is based upon division of the eigenstructure of the sample covariance into approximate signal and noise subspaces due to fluctuations caused by finite data samples. These fluctuation effects are calculated using stochastic perturbation theoretic techniques. These results show that the moments of the MUSIC null spectrum can be approximated by linear functionals of the source SNR and the number of snapshots. All theoretical predictions are in accord with the simulation results. A featured simulation demonstrates accurate source power estimates for three sources separated by sub-Rayleigh resolution spatial frequencies with a weak source of 0 dB SNR sandwiched between two much larger sources of 40 and 20 dB View full abstract»

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  • Multi-layer adaptive filtering

    Publication Year: 1992 , Page(s): 58 - 61
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    The structure of the multilayer adaptive filter is similar to that of a multilayer perceptron with an input layer to which signal samples are presented, an output layer where the estimated signal is obtained, and one or more intermediate layers of nodes. This paper describes the multi-layer adaptive algorithm, and numerical examples illustrate its performances View full abstract»

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  • Measuring instabilities and chaos in the real world: applications in rotating machinery

    Publication Year: 1992 , Page(s): 217 - 220
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    Rotor dynamic instabilities have resulted in seldom understood and costly failures in high-performance rotating machinery. At times, machines test perfectly in the lab, yet fail under load and cannot achieve their designed capacities in the field. Nonlinear dynamics offers a way to help understand and possibly prevent these problems. Computed order tracking prepares experimental data for dynamical analysis by resampling data in real time to match a time-varying forcing function which in this instance is the rotational speed of the machine. A commercially available instrument can be used to view Poincare diagrams of a rotor test set as it begins to exhibit signs of instability View full abstract»

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  • Least squares predictive transform space-time array processing for adaptive airborne MTI radar

    Publication Year: 1992 , Page(s): 65 - 69
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    A novel strategy is presented via the application of a multichannel least squares predictive transform (PT) signal modeling procedure. The crux of the technique is the utilization of a multichannel adaptive `whitening' filter obtained from least squares PT signal modeling to `pre-whiten' the otherwise angle-Doppler correlated clutter signal prior to detection. The synergistic effect of the prediction and transformation mechanisms provides additional means for reducing both design and implementation complexity while gradually trading off performance-as measured by the degree of clutter cancellation for the application considered. Simulation results demonstrate the utility of the approach in a radar employing an eight element phased array antenna operating in Rayleigh distributed clutter View full abstract»

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  • A new cumulant based inverse filtering algorithm for identification and deconvolution of nonminimum-phase systems

    Publication Year: 1992 , Page(s): 144 - 147
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    This paper proposes a new filtering algorithm for linear time-invariant systems with only non-Gaussian output measurements contaminated by Gaussian noise. Some simulation results demonstrate that the algorithm works well View full abstract»

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  • Least-squares reconstruction of an image from its noisy observations using the bispectrum

    Publication Year: 1992 , Page(s): 156 - 159
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    The observed images are allowed to be spatially shifted with respect to one another, and the observation noise is assumed to be Gaussian. An algorithm is proposed that recovers the image by separately reconstructing its Fourier phase and Fourier log-magnitude, in the least-squares sense, from the modulo-2π phase and log-magnitude of the bispectrum of the image estimated from the given noisy observations. A technique proposed by the authors is used to unwrap the modulo-2π bispectral phase and to reconstruct the Fourier phase of the image. Experimental results demonstrate the performance of the proposed algorithm View full abstract»

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