• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2454-2468
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• 2019

The existing direct position determinations(DPD) for coherently distributed(CD) sources are mostly applicable for uniform linear array(ULA), which result in a low degree of freedom(DOF), and it is difficult for them to realize the effective positioning in underdetermined condition. In this paper, a novel DPD algorithm for coherently distributed sources based on compressed sensing with a moving nested array is present. In this algorithm, the nested array is introduced to DPD firstly, and a positioning model of signal moving station based on nested array is constructed. Owing to the features of coherently distributed sources, the cost function of compressed sensing is established based on vectorization. For the sake of convenience, unconstrained transformation and convex transformation of cost functions are carried out. Finally, the position coordinates of the distribution source signals are obtained according to the theory of optimization. At the same time, the complexity is analyzed, and the simulation results show that, in comparison with two-step positioning algorithms and subspace-based algorithms, the proposed algorithm effectively solves the positioning problem in underdetermined condition with the same physical element number.

• The Journal of the Acoustical Society of Korea
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• v.20 no.5
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• pp.110-115
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• 2001

In this paper, we propose a beamformer adequate for the nested away that is generally used for multiple frequency band signal processing. The nonisotropic beam pattern of channel in this array causes two problems: the bearing-estimate error of mainlobe and the difference between design and output in sidelobe level. By separating the time delay among channel signals and the time delay among sensor signals in channel, we can remove the effects of the nonisotropic beam pattern of channel in the beamformer output. Through this process, a method to correct simultaneously these problems is proposed.

• ETRI Journal
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• v.43 no.5
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• pp.869-880
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• 2021

Herein, we estimate the direction of arrival (DOA) of non-Gaussian signals for nested arrays (NAs) by implementing the fourth-order difference co-array (FODC) and successive methods. In particular, considering the property of the fourth-order cumulant (FOC), we first construct the FODC of the NA, which can obtain O(N⁴) virtual elements using N physical sensors, whereas conventional FOC methods can only obtain O(N²) virtual elements. In addition, the closed-form expression of FODC is presented to verify the enhanced degrees of freedom (DOFs). Subsequently, we exploit the vectorized FOC (VFOC) matrix to match the FODC of the NA. Notably, the VFOC matrix is a single snapshot vector, and the initial DOA estimates can be obtained via the discrete Fourier transform method under the underdetermined correlation matrix condition, which utilizes the complete DOFs of the FODC. Finally, fine estimates are obtained through the spatial smoothing-Capon method with partial spectrum searching. Numerical simulation verifies the effectiveness and superiority of the proposed method.

• The Journal of the Acoustical Society of Korea
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• v.38 no.2
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• pp.231-239
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• 2019

In sonar systems, the passive ranging of a target is an active research area. This paper analyzed the performance of passive ranging based on an array invariant method for different environmental and sonar parameters. The array invariant developed for source range estimation in shallow water. The advantages of this method are that detailed environmental information is not required, and the real-time ranging is possible since the computational burden is very small. Simulation was performed to verify the algorithm. And this method is applied to sea-going experimental data in 2013 near Jinhae port. This study shows the performance of ranging for source orientation, transmission signal length, and length of a receiver through numerical simulation experiments. Also, the results using nested array and uniform line arrays are compared.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1267-1270
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• 1998

This paper analyzes the characteristics of wide-band one-shot beam formed by using all sensors of array at once, as variation of weighting width. Gaussian function is applied to each sensor as a role of weighting. As the results of the simulation for nested linear array having 17 sensors for each octave, as the width goes wider the directivity index(DI) becomes lower but more even and the variation of beamwidth becomes smaller. It is confirmed, therefore, that weighting width is carefully decided in consideration of DI level, DI stability and the beamwidth.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.61-67
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• 1999

This paper proposes a new beamforming algorithm for acoustic measurement by using the nested linear array. In this algorithm, the weighting is optimized by minimizing the LMS error with the initial value obtained by FIR filter design algorithm. The optimization process is applied to each sub-band, which is divided from the octave band, to produce the uniform directivity index. For the optimization pseudo inverse matrix is used for the transfer matrix. As the simulation results, it is found that the proposed algorithm can get the desired beam pattern and unform directivity index so as to be used efficiently for the acoustic measurement by using a nested linear array.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.285-292
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• 2007

SoC which deploys software modules as well as hardware IPs on a single chip is a major revolution taking place in the implementation of a system design, and high-level synthesis is an important process of SoC design methodology. Recently, SPARK parallelizing high-level synthesis software tool has been developed. It takes a behavioral ANSI-C code as an input, schedules it using code motion and various code transformations, and then finally generates synthesizable RTL VHDL code. Although SPARK employs various loop transformation algorithms, the synthesis results generated by SPARK are not acceptable for basic signal and image processing algorithms with nested loop. In this paper we propose a SoC platform with an application-specific PLD targeting local operations which are feature of many loop algorithms used in signal and image processing, and demonstrate design process which maps behavioral specification with nested loops written in a high-level language (ANSI-C) onto 2D systolic array. Finally the derived systolic array is implemented on the proposed application-specific PLD of SoC platform.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.639-642
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• 1998

This paper proposes a new wide-band beamforming which has guassian weighting. For the prupose of measurement this beam is formed by using all sensors toghether, not octave-by-octave. Weighting is applied to each sensor before time-delay compensation as a frequency-dependent function. As the resutls of the simulation of the proosed algorithm for nested linear array having 17 sensors for each octave, it is confirmed that beam can be formed with all sensors together and uniform directivity index can be achieved by proposed algorithm.

• Journal of the Korea Convergence Society
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• v.6 no.3
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• pp.103-109
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• 2015

TOLED(Transparent, Organic Light Emitting Diodes) based edutainment system has been studied to solve the actual feeling training and educational experience problem of e-learning. However, edutainment system using TOLED has a problem for the non-detection of multi marker array and rotate marker array, and it has problem for the dissonance phenomena caused by Illumination Environment between real world and virtual object. It also has a do not provide services through a variety of devices problem. Therefore, in this paper, we designed a system that provides a realistic actual feeling edutainment contents by recognizes the marker array rotation and a plurality of marker arrangement via an improved marker detection technique. And to unify the real space and virtual space of the lighting environment through a nested block layer.

• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.25-31
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• 1999

This paper proposes a new wide-band beamforming algorithm which has Gaussian weighting at nested linear array for acoustic measurement. The beamforming is performed one-shot by using all sensors simultaneously, not octave-by-octave. Gaussian weighting of frequency-dependent function is applied to each sensor before time-delay compensation so as to control the frequency receiving band of each sensor. As the results of the simulations, it is confirmed that the proposed algorithm can form the one-shot beams having uniform directivity index and also it can be applied to the broad-band acoustic measurement.