A Novel Near-Field Localization Method Based on Second Order Statistics

2008 ◽  
Author(s):  
Hongbo Liu ◽  
Wei Zhang
Keyword(s):  
Order Statistics ◽  
Near Field ◽  
Second Order ◽  
Localization Method ◽  
Second Order Statistics ◽  
Field Localization

Second-Order Statistics-Based Multi-Parameter Estimation of Near-Field Acoustic Sources

2013 ◽  
Vol 461 ◽  
pp. 977-983
Author(s):  
Xin Bo Li ◽  
Nan Nan Liu ◽  
Nan Jiang ◽  
Xiao Bo Long ◽  
Xiao Yang Jiao
Keyword(s):  
Parameter Estimation ◽  
Order Statistics ◽  
Linear Array ◽  
Near Field ◽  
Second Order ◽  
Uniform Linear Array ◽  
Acoustic Vector Sensor ◽  
Second Order Statistics ◽  
Vector Sensor ◽  
Acoustic Sources

In this paper, a new approach based on the second-order statistics (SOS) and acoustic vector sensor (AVS) array is proposed, for localization estimation of near-field acoustic narrowband sources. Firstly, we choose the centrosymmetric uniform linear-array as the AVS arrangement, and the array is consistent with the coordinate axis direction of the acoustic vector-sensor. This estimation method makes good use of the acquisition information from the AVS, such as one-dimensional sound pressure and three-dimensional particle velocity, and has shown preferable performance for the parameter estimation of direction-of-arrival (DOA) and range of target acoustic sources in the near field. The estimation algorithm expands the near-field array manifold of one single acoustic vector sensor to the acoustic vector-sensor’s uniform linear-array, and the near-field acoustic vector sensor linear array output model is deduced. The autocorrelation and cross-correlation function of the velocity field and the pressure field are used to construct the rotational invariance frame, which helps to extract the expected information. Consequently, the closed-form solutions of the incident source’s DOA and range are derived explicitly through the parameter pairing operation. The proposed method reduces the computational burden and has good spatial recognition ability and high resolution in the case of limited array elements. It also has better engineering application prospect. Eventually, the performance of the method is verified by Monte Carlo simulation experiments.

Properties of Acoustical Speckle in the Presence of Phase Aberration Part II: Correlation Lengths

1988 ◽  
Vol 10 (1) ◽  
pp. 29-51 ◽  
Author(s):  
Stephen W. Smith ◽  
Gregg E. Trahey ◽  
Sylvia M. Hubbard ◽  
Robert F. Wagner
Keyword(s):  
Order Statistics ◽  
Near Field ◽  
Second Order ◽  
Lesion Detection ◽  
Main Lobe ◽  
Phase Aberration ◽  
Spatial Compounding ◽  
Second Order Statistics ◽  
Speckle Size ◽  
Phase Aberrations

In recent years, analysis of the second order statistics of ultrasound speckle has led to accurate prediction and measurements of the average speckle size in the transducer focal zone. In this paper, that work has been extended to the average speckle size as determined by the normalized autocovariance in the presence of transducer phase aberrations. In general, a phase aberration causes a narrowing of the main lobe of the normalized autocovariance in the lateral direction. However, the lateral speckle autocovariance also showed significant side lobes in the presence of phase aberrations, indicating that individual speckles in a region of interest are not independent but are correlated so that less information is present for the task of signal detection when a transducer phase aberration exists. The same evidence of correlated speckle was found in the near field of a transducer in the region of fine speckle texture. This explanation satisfies the quandary of poor detectability in the near field region where the speckle is fine but the lateral resolution is quite degraded. The axial speckle in the presence of phase aberrations showed a small increase in main lobe widths and no evidence of side lobes. Beginning in 1978, the analysis of the second order statistics of speckle images for the purpose of spatial compounding led to accurate measurement and prediction of the cross-correlation curve as a function of transducer aperture translation for purposes of spatial compounding. In this paper, that work has been extended to the presence of transducer phase aberrations. The existence of transducer phase aberrations causes significant increases in the rate of decorrelation of speckle interference patterns as a transducer is translated. This indicates that spatial compounding will result in quite significant improvements in area-wise SNR and low contrast lesion detection for the case of severe random aberrators or focal point errors.

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