Root-MUSIC Method Research Articles

Enhancing the efficiency of spectral analysis of signals by the Root-MUSIC method using surrogate data

A problem of enhancing the efficiency of spectral analysis of signals observed against the background of noise by using the Root-MUSIC method and the technology of surrogate data obtained by the randomization of phases of spectral components of observations has been considered. The results of spectral analysis simulation are presented. The application of this technology was shown to be effective at small and large values of the signal-to-noise ratio when the frequencies of signal components are a multiple of the observation sampling frequency.

Bearing and Range Estimation for Multiple Near-Field Sources based on Ambiguity Function

Abstract AD-MUSIC is introduced to near-field to investigate the bearing and range estimation for the mixed source localization of sinusoidal signal and LFM signal. Firstly, a near-field two-dimensional MUSIC method based on ambiguity function distribution is put forward. Further, a novel Root-MUSIC method which constructs two ambiguity function distribution matrices is proposed for near-field source localization. The simulation results show that the two ambiguity function based methods have higher accuracy and resolution for the position estimation of the mixed-source signals compared with WVD based methods and conventional algorithms, even when the signal-to-noise ratio is low.

Multidimensional Sinusoidal Frequency Estimation Using Subspace and Projection Separation Approaches

In this correspondence, a computationally efficient method that combines the subspace and projection separation approaches is developed for R -dimensional (R-D) frequency estimation of multiple sinusoids, where R ≥ 3, in the presence of white Gaussian noise. Through extracting a 2-D slice matrix set from the multidimensional data, we devise a covariance matrix associated with one dimension, from which the corresponding frequencies are estimated using the root-MUSIC method. With the use of the frequency estimates in this dimension, a set of projection separation matrices is then constructed to separate all frequencies in the remaining dimensions. Root-MUSIC method is again applied to estimate these single-tone frequencies while multidimensional frequency pairing is automatically attained. Moreover, the mean square error of the frequency estimator is derived and confirmed by computer simulations. It is shown that the proposed approach is superior to two state-of-the-art frequency estimators in terms of accuracy and computational complexity.

An Estimation of Angular Coordinates and Angular Distance of Two Moving Objects by Using the Monopulse, MUSIC, and Root-MUSIC Methods

The paper presents results of extensive simulations carried out in order to assess the precision and angular resolution of subspace methods in real radar system. It has been assumed that such a system uses the 32-element uniform linear array (ULA) and radiates only 3 bursts consisting of 8 pulses in given direction. In order to avoid blind Doppler frequencies, pulse repetition interval (PRI) is different in each burst. It has been shown that change of PRI is not only necessary to avoid blind Doppler frequencies but also allows to avoid false values of angular coordinates when two objects are visible in the same beam, in the same range gate, and their echoes attain maximal values in the same Doppler filter. It has also been shown that precision and angular resolution of both MUSIC and root-MUSIC method can be improved by appropriate preprocessing of signal samples used by these methods.

Flaw detection and thin materials thickness measurement using time frequency and high resolution algorithms

Several techniques of signal processing were introduced in ultrasonics NDT field. In thin samples the reflected signals are overlapping thus making detection of defects in these samples and accurate measurements impossible. It is thus necessary to enhance the visibility of the defect echo by signal processing techniques. In this context, we develop signal processing tools allowing detecting and locating the imperfections present in these materials. In this paper, we contribute by the development of some signal processing techniques based on time frequency and high resolution algorithms in order to enhance the resolution of flaw detection and to measure thin materials thickness. 1- We propose to implement temporal versions of methods known as high resolution like MUSIC, Root MUSIC and Eigen vectors method. These methods allow frequencies extraction in the case of the complex signals drowned in noise. 2- We apply time-frequency algorithms based on STFT, Wigner-Ville, Gabor transform on thin materials thickness measurement. A comparative study is carried out between all of these algorithms and is applied in separation of closer flaw echoes and thin materials thickness measurement. Satisfactory results are obtained with Gabor transform in measurement of few tenth (0.1) mm.

DOA Estimation for Coherent Sources in Unknown Nonuniform Noise Fields

A new algorithm, called generalized covariance differencing (GCD), is proposed for direction of arrival (DOA) estimation in the presence of coherent sources and unknown nonuniform noise. By using the difference between the forward-backward spatial smoothing matrix and its complex conjugation, the GCD method constructs a generalized covariance matrix, which can fully eliminate spatially nonuniform noise and fit for more general noise fields and low signal-to-noise ratio (SNR) environments. In addition, it can also resolve coherent and incoherent sources. The GCD covariance matrix is an imaginary-valued matrix which can reduce computational burden. By analyzing the characteristic of GCD, a rapid root-MUSIC method without eigendecomposition is also given which can further reduce computational complexity. Simulation results demonstrate that the GCD method can effectively eliminate nonuniform noise, and it possesses a lower SNR threshold as well as a smaller variance than that of conventional methods.

Considerations on estimation accuracy improvement of modified root-MUSIC algorithm for frequency dispersion detection of electromagnetic scattering wave

The strong resolving capacity of the superresolution method is effective for the analysis of local scattering of electromagnetic waves. In this paper, as an example of scattering phenomena in which a scattered wave with frequency dispersion is included, backscattering from a circular waveguide is discussed. The accuracy of estimation of the parameters related to frequency dispersion by the improved Root-MUSIC method is discussed. In particular, a new form of postprocessing is proposed in addition to the preprocessing used as a data correction method in the improved Root-MUSIC method. The advantages of postprocessing are discussed. Further, by numerical calculation and experiment, it is demonstrated that the estimation accuracy of the present method can be improved by including a notch filter in the time domain. © 2001 Scripta Technica, Electron Comm Jpn Pt 1, 84(5): 48–56, 2001