• The Journal of the Acoustical Society of Korea
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• v.27 no.5
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• pp.221-228
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• 2008

To estimate array shape with reference sources in SONAR systems, nearfield signal modeling is required for the reference sources near a towed array. Array shape estimation method based on the nearfield signal modeling generally exploits the spatial covariance matrix of the received reference sources. Among those method, nearfield eigenvector method uses the eigenvector corresponding to the maximum eigenvalue as a steering vector of the reference source. In this paper, we propose a simplified subspace fitting method based on the nearfield signal modeling with spherical wave modeling. Furthermore, we analyze performance of the array shape estimation methods based on the nearfield signal modeling for various environments. The results of the numerical experiments indicate that the simplified subspace fitting method and the nearfield eigenvector method with single reference source shows almost similar performance. Furthermore, the simplified subspace fitting method with 2 reference sources consistently estimates the shape of the array regardless of the incident angle of the reference sources, whereas the nearfield eigenvector method cannot apply for the case of 2 reference sources.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.295-302
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• 1990

In this paper, a methodology for the automatic design of the optimal systolic arrays is proposed. Algorithm transformation is the main mathematical tool on which this methodology is based. Also, technique for partitioning algorithm into systolic arrays is presented. Algorithm partitioning is essential when the size of the computational problem is larger than the size of the array. This study results in (a) reduction of the design time of systolic arrays for given algorithms, (b) CRT display of the structures of systolic arrays, and (c) automatic designing of the optimal systolic array by the criteria such as the number of processing elements, bands, and communication paths. The procedure for these results was programmed using HP BASIC language on HP-9836 computer.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.288-291
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• 2003

본 논문에서는 모듈성과 확장성을 갖는 시스톨릭 어레이를 이용한 두 띠 행렬의 비트 연속 승산기 구현에 대하여 기술한다. 띠 폭이 3인 4$\times$4 띠 행렬이 주어질 때 워드 레블 승산기 설계를 위한 3차원 DG로부터 2차원 시스톨릭 어레이를 유도한 후, 워드 레블 PE를 비트 연속 승산기와 가산기를 이용하여 비트 레블 PE로 변환시켜 띠 행렬의 비트 레블 승산기를 설계한다. 구현된 워드 레블 승산기와 비트 레블 승산기는 RT 수준에서 VHDL로 모델링하여 동작을 검증하였다. 검증된 시스톨릭 어레이를 이용한 워드 레블 승산기와 비트 레블 승산기는 Hynix에서 제공하는 0.35$\mu\textrm{m}$ 셀 라이브러리를 사용하여 Synopsys design compiler로 합성되었다.

• The Journal of the Acoustical Society of Korea
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• v.12 no.1E
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• pp.39-47
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• 1993

2-Dimension IIR 디지털 필터를 시스토릭 어레이 구조로 실현하는 방법을 보였다. 시스토릭 어레이는 1-D IIR 디지털 필터로 부분 실현한 후 종속연결하여 구현하였다. 부분 실현한 시스토릭 어레이의 종속 연결은 신호 지연에 사용되는 요소를 감소 시킨다. 여기서 1-D 시스토릭 어레이는 local communication 접근에 의해 DG를 설계한후 SFG로의 사상을 통해 유도하였다. 유도된 구조는 매우 간단하며, 입력 샘플이 공급되어지면 매 샘플링 기간마다 새로운 출력을 얻는 매우 높은 데이터 처리율을 갖는다. 2-Dimension IIR 디지털 필터를 시스토릭 어레이로 실현함으로써 규칙적이고, modularity, local interconnection, 높은 농기형 다중처리의 특징을 갖기 때문에 VLSI 실현에 매우 적합하다. 또한 PE셀의 승산기 설계에서는 modified Booth's 알고리즘과 Ling's 알고리즘에 기초를 두고 고도의 병렬처리를 행할수 있도록 설계하였다.

• The Journal of the Acoustical Society of Korea
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• v.21 no.5
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• pp.478-484
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• 2002

Linear towed arrays (LTA) have a nonlinear shape due to tow vessel motion, ocean swells and currents. By reasons of nominally linear shape, various towed array shape estimation techniques have been developed since the perturbed shape cause the error in target detection. In this paper,, we propose the beamforming method for the perturbed LTA with simple structure. The proposed method linearizes a nonlinear phase of steering vector with position information measured by two reference sensors. It can be proved using some properties of Markov transition matrix, and iteration number of linearization process is decided by variance of cross phase difference. As a result of computer simulation in the ocean environment, beampattern of the proposed method is almost same with the ideal case in my type of array shape. In the signal-to-noise ratio (SNR) performance simlation, the DOA estimation performance of the proposed beamforming method is evaluated, and the comparison with Bartlett beamformer of the LTA shows that the proposed method can estimate. the spatial characteristic of sources more accuracy.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.293-296
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• 2007

In this paper, we propose the systolic array architecture for the vector median filter. In the color image processing, the vector signal (i.e. the color) consists of three elements, red, green and blue. The vector median filter is very effective to utilize the correlation among red, green and blue elements. The computational complexity of the proposed architecture for computing the vector median of N vector signals is (N+2) clock periods compared to the (3N+1) clock periods in the previous method. In addition to, the input vector signals can be loaded in serial in the proposed architecture. In the previous method, N input vector signals should be loaded to the vector median filter in parallel at the first clock. The proposed architecture is implemented with FPGA.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.87-91
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• 2003

It has well known that MUSIC and ESPRIT algorithms estimate angle of arrival(AOA) with high resolution by eigenvalue decomposition of the covariance matrix which were obtained from the array antennas. However, the disadvantage of MUSIC and ESPRIT is that they are computationally ineffective, and then they are difficult to implement in real time. The other problem of MUSIC and ESRPIT is to require calibrated antennas with uniform features, and are sensitive to the manufacturing facult and other physical uncertainties. To overcome these disadvantages, several method using neural model have been study. For multiple signals, those require huge training data prior to AOA estimation. This paper proposes the algorithm for AOA estimation by interconnected hopfield neural model. Computer simulations show the validity of the proposed algorithm. The proposed method does not require huge training procedure and only assigns interconnected coefficients to the neural network prior to AOA estimation.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.46-51
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• 2015

In this paper, I design a linear array antenna simulator for anti-jamming GPS systems and perform various performance analysis by simulation. First, I generate simulated transmission signals through the analysis of GPS satellite signal structure, and analyze SNR(Signal to Noise power Ratio) performance of linear array antenna according to number of arrays under noise environments. In addition, I analyze the performance of the anti-jamming beam pattern using MMSE(Minimum Mean Square Error) signal processing method, and also analyze the anti-jamming performance considering antenna calibration problem when there are different delays between arrays.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.543-548
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• 2002

It has been known that the DCMP(Directionally Constrained Minimization of Power) and the ZF(Zero Forcing) can improve the SINR performance of an array antenna system by using spatial signature of wireless channel. This paper analyzes the performance of DCMP and ZF in multiple scattering environments. To obtain the spatial signature of wireless channel. both DOA(Directional of Arrival) and AS(Angular spread) of the received signals were estimated by using ESPRIT. The performance of the DCMP and the ZF was analyzed theoretically. By computer simulation of SINR performance was evaluated.

• The Journal of the Acoustical Society of Korea
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• v.29 no.1
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• pp.24-33
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• 2010

This paper proposes a technique of sound beamforming that can generate high-directive sound beams, and this paper also presents applications of the proposed algorithm to multi-channel 3D sound systems. The proposed algorithm consists of two phases: first, optimum weights maximizing a sound pressure level ratio between the target and control acoustic regions are designed, and later, the directivity of the pre-designed sound beam is iteratively enhanced by modifying the covariance matrix. The proposed method was evaluated under various situations, and the results showed that it could provide more focused sound beams than the conventional methods.