A Derivative-Based MUSIC Algorithm for Two-Dimensional Angle Estimation Employing an L-Shaped Array

The estimation speed of positioning parameters determines the effectiveness of the positioning system. The time of arrival (TOA) and direction of arrival (DOA) parameters can be estimated by the space-time two-dimensional multiple signal classification (2D-MUSIC) algorithm for array antenna. However, this algorithm needs much time to complete the two-dimensional pseudo spectral peak search, which makes it difficult to apply in practice. Aiming at solving this problem, a fast estimation method of space-time two-dimensional positioning parameters based on Hadamard product is proposed in orthogonal frequency division multiplexing (OFDM) system, and the Cramer-Rao bound (CRB) is also presented. Firstly, according to the channel frequency domain response vector of each array, the channel frequency domain estimation vector is constructed using the Hadamard product form containing location information. Then, the autocorrelation matrix of the channel response vector for the extended array element in frequency domain and the noise subspace are calculated successively. Finally, by combining the closed-form solution and parameter pairing, the fast joint estimation for time delay and arrival direction is accomplished. The theoretical analysis and simulation results show that the proposed algorithm can significantly reduce the computational complexity and guarantee that the estimation accuracy is not only better than estimating signal parameters via rotational invariance techniques (ESPRIT) algorithm and 2D matrix pencil (MP) algorithm but also close to 2D-MUSIC algorithm. Moreover, the proposed algorithm also has certain adaptability to multipath environment and effectively improves the ability of fast acquisition of location parameters.

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Two dimensional angle estimation using separate nested acoustic vector sensor array

2017 9th International Conference on Wireless Communications and Signal Processing (WCSP) ◽

10.1109/wcsp.2017.8170923 ◽

2017 ◽

Author(s):

Jianfeng Li ◽

Feng Wang ◽

Xiaofei Zhang

Keyword(s):

Sensor Array ◽

Two Dimensional ◽

Acoustic Vector Sensor ◽

Angle Estimation ◽

Vector Sensor ◽

Vector Sensor Array

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Doppler Angle Estimation of Pulsatile Flows Using AR Modeling

Ultrasonic Imaging ◽

10.1177/016173460202400201 ◽

2002 ◽

Vol 24 (2) ◽

pp. 65-80 ◽

Cited By ~ 6

Author(s):

Chih-Kuang Yeh ◽

Pai-Chi Li

Keyword(s):

Real Time ◽

Doppler Spectrum ◽

Acquisition Time ◽

Two Dimensional ◽

Flow Measurements ◽

Angle Estimation ◽

Flow Angle ◽

Doppler Angle ◽

Wide Range ◽

Pulsatile Flows

In quantitative ultrasonic flow measurements, the beam-to-flow angle (i.e., Doppler angle) is an important parameter. An autoregressive (AR) spectral analysis technique in combination with the Doppler spectrum broadening effect was previously proposed to estimate the Doppler angle. Since only a limited number of flow samples are used, real-time two-dimensional Doppler angle estimation is possible. The method was validated for laminar flows with constant velocities. In clinical applications, the flow pulsation needs to be considered. For pulsatile flows, the flow velocity is time-varying and the accuracy of Doppler angle estimation may be affected. In this paper, the AR method using only a limited number of flow samples was applied to Doppler angle estimation of pulsatile flows. The flow samples were properly selected to derive the AR coefficients and then more samples were extrapolated based on the AR model. The proposed method was verified by both simulations and in vitro experiments. A wide range of Doppler angles (from 30° to 78°) and different flow rates were considered. The experimental data for the Doppler angle showed that the AR method using eight flow samples had an average estimation error of 3.50° compared to an average error of 7.08° for the Fast Fourier Transform (FFT) method using 64 flow samples. Results indicated that the AR method not only provided accurate Doppler angle estimates, but also outperformed the conventional FFT method in pulsatile flows. This is because the short data acquisition time is less affected by the temporal velocity changes. It is concluded that real-time two-dimensional estimation of the Doppler angle is possible using the AR method in the presence of pulsatile flows. In addition, Doppler angle estimation with turbulent flows is also discussed. Results show that both the AR and FFT methods are not adequate due to the spectral broadening effects from the turbulence.

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