• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.141-144
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• 2004

수중 음향 탐지 시스템에서 빔 형성 기법은 오랫동안 많은 연구자들에 의해 연구되어 왔다. 빔 형성 기법은 탐지성능에 직결되기 때문에 최적의 빔 설계는 중요한 문제가 된다. 그리고 최적의 빔 형성기를 구현하기 위해서는 개별 센서에 대한 가중회로의 구성이 필수적이며, 가중회로를 구성하기 위해서는 개별 센서에 대한 등가회로 모델링과 정합회로 설계가 필수적이다. 이전의 연구에서는 센서 등가회로 모델링 Tool과 정합회로 디자인 Tool 각각의 구성과 사용방법에 대해서 소개하였다. 본 논문에서는 이 두 가지 Tool을 모두 이용하여 센서 등가회로 및 정합회로를 모델링하였고, 이를 바탕으로 실제 가중회로를 구현하였다. 실험을 위해 물-공기의 상사효과를 가정하였으며, 공기 중에서 스피커 어레이를 이용하여 빔 형성을 하였다. 또한, 이론치와 실험치를 비교하여 BeamCAD, 센서 등가회로 모델링 Tool 그리고 정합회로 디자인 Tool로 이루어진 소나 센서 디자인 Tool의 타당성을 검증하였다.

• 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 Broadcast Engineering
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• v.8 no.2
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• pp.136-145
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• 2003

This paper proposes a DTV receiver using beamforming techniques to improve indoor and mobile reception. The proposed DTV receiver estimates the directions of arrival (DOAs) of incoming signals using Capon's DOA estimation method and generates an adaptive antenna beam pattern to the estimated DOA of the mainpath signal to Improve the channel condition. After beamforming, a following decision feedback equalizer (DFE) removes the remaining multipath components. The proposed receiver can be implemented with a conventional DTV receiver without anymodification. The performance of the proposed receiver is analyzed with modified Brazilian field test models, which include DOA information of Incoming signals. Simulation results show that the proposed receiver can satisfy the threshold of visibility (TOV) when input signal to noise ratio is slightly over 10 dB.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.479-486
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• 2015

A triplet line array has a capability for solving left/right ambiguity problem and high directivity of line array. For this, high computational powers and correlation between nearby sensors must be considered. Hardware powers are dramatically increased, so various adaptive beamforming techniques and signal processing techniques can be adopted for large triplet line array. To investigate the optimum signal processing method and improve the target detection capability, we need to analyze the noise correlation among the triplet line array sensors in real environment. In this paper we analyze the experimental data in the East Sea, investigate noise correlation between three hydrophones in triplet sensors, among the triplet sensors and time varying properties. Based on the acquired results, it is possible to verify some information for beamforming and signal processing methods with considering the properties of the triplet line array.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.21-29
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• 2001

In order to detect the precise port/starboard direction of arrival of target signal in real noisy ocean environments, Inverse beamforming (IBF) algorithm is surveyed theoretically and the detection performances of IBF are analyzed with simulations. Cardioid Inverse beamforming algorithm was proposed for port/starboard discrimination and the performance was studied with simulations. It is shown that IBF has a 3dB array gain advantage over Conventional beamforming (CBF) under ideal conditions. This 3 dB advantage is proven theoretically and illustrated with simulations. The fact that the IBF beamwidth is narrower than the CBF beamwidth by a factor of 0.68 proves the performance of defection and spatial resolution improvement. Comparing the simulation results of Cardioid Inverse beamforming and Conventional Cardioid beamforming, it is shown that Cardioid Inverse beamformer has enhanced performance in minimum detection level, detection accuracy and resolution. Due to the results of moving target bearing detection test in endfire, it is shown that Cardioid Inverse beamformer has better performance, comparing the Conventional Cardioid beamformer.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.208-217
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• 2013

When a beamforming can be processed separately in horizontal and vertical directions with the planar arrays used in sonar systems, there are several merits such as that practically reduce the required computations and volumes. However, the common planar arrays used in sonar systems are generally non-separable, so the beamforming with separable weighting results in the differences between the desired beam characteristics and the resultant beam characteristics. In this paper, we propose a new separable weighting method which can achieve the wanted beam characteristics by using the separable weights in horizontal and vertical directions for the non-separable planar arrays. In order to achieve the wanted beam characteristics, the proposed method minimizes the differences between the desired weights and the resultant weights based on the number of effective sensors in horizontal and vertical directions of the planar arrays.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.285-292
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• 2007

Magnetotelluric data recorded in the middle part of the Korean Peninsula are contaminated by severe noises at dead-band frequencies. In this study, we estimated the location of noise source using a source localization method. Since conventional beamforming techniques were not adequate for the localization of electromagnetic sources, we used the matched field processing and a genetic algorithm. The solutions for the strong noise signals tend to be localized in a narrow area, whereas those for natural MT signals shows randomly distributed patterns. The strong noise sources are mainly located in the western part of Kyonggi-do.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.8
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• pp.608-614
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• 2018

This paper describes the synthesis method for an adaptive SLB channel, which is robust to interference in the ULA radar system. The SLB channel based on the spatial DLC can be synthesized simply and is effective in blanking the signal coming from the sidelobe. We combined it with adaptive beamforming, which removes the strong interference using its correlation matrix. The adaptive SLB channel would suppress the interference below the noise, so it has good performance in an interference environment. This research will be applicable to planar array systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.777-782
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• 2017

The Signal Intelligence (SIGINT) system based on the adaptive beamformer, comprised of the AOA estimator followed by the interference canceller, is a cutting edge technology for collecting various signal information utilizing all sorts of devices such as the radar and satellite. In this paper, we present the efficient adaptive SIGINT structure consisted of an AOA estimator and an adaptive beamformer. For estimating AOA information of various signals, we employ the Multiple Signal Classification (MUSIC) algorithm and for efficiently suppressing high-power interference signals, we employ the Minimum Variance Distortionless Response (MVDR) algorithm. Also, we provide computer simulation examples to verify the performance of the presented adaptive beamformer structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.490-495
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• 2009

An approach to 3D visualization of multiple sound sources has been developed with the application of a moving array technique. Frequency-domain beamforming algorithm is used to generate a beam power map and the sound source is modeled as a point source. When a conventional delay and sum beamformer is used, it is considered that 2D distribution of sensors leads to have deficiency in spatial resolution along a measurement distance. The goal of moving an array in this study is to form 3D array aperture surrounding multiple sound sources so that the improved spatial resolution in a virtual space can be expected. Numerical simulation was made to examine source localization capabilities of various shapes of array. The 3D beam power maps of hemispherical and spherical distribution are found to have very sharp resolution. For experiments, two sound sources were placed in the middle of defined virtual space and arc-shaped line array was rotated around the sources. It is observed that spherical array show the most accurate determination of multiple sources' positions.