• The Journal of the Acoustical Society of Korea
• /
• v.22 no.6
• /
• pp.489-495
• /
• 2003

Single towed line array receiver contains an ambiguity on conjugate bearings because of lacking aperture in transverse direction. To solve the left/right bearing ambiguity of line array receiver this paper proposed using single line array with fixed cardioid beam. Fixed cardioid beam has problem about back beam gain exists for steering beam inherent. Back beam is makes form on direction that is different from actually source so that reduced the performance of left/right bearing discrimination. In this paper, line way with adaptive cardioid beam for resolve problem of back beam gain is proposed. So the proposed method has more improved left/right bearing discrimination than fixed cardioid beam, Simulation results show the performance of the proposed method.

• The Journal of the Acoustical Society of Korea
• /
• v.36 no.2
• /
• pp.115-122
• /
• 2017

We propose a robust adaptive beamforming algorithm for triplet array sonar. The proposed beamforming algorithm obtains robustness to mismatches, left/right discrimination, and has two steps. The first is a cardioid beamformer, which supports left/right discrimination of target signals. It applies the conventional delay-and-subtract to each triplet's signal with its rotation angle and obtains multiple cardioid beams. The second is a robust adaptive beamforming to minimize nearby interferences. We regard cardioid beams as input signals of a line array and apply an adaptive beamforming algorithm to the cardioid beams. Simulations results show that the proposed algorithm provides significantly better performance than the conventional algorithms, while supporting left/right discrimination of target signals.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1993.06a
• /
• pp.222-225
• /
• 1993

일반적임 빔 형성기는 표적의 방위탐지가 가능하지만, 구조적인 특성상 대칭적인 빔을 형성하므로 표적의 좌/우 방위 구분이 불가능하기 때문에 표적의 정확한 방위를 탐지하고자 할 때 좌/우 구분이 가능한 빔 형성기가 필수적이다. 좌/우 분리 빔 형성 기법으로는 카디오이드(Cardioid) 빔 형성기법을 일반적인 빔 형성기에 적용시키는 방법이 최적으로 알려져 왔다. 그러나 좌/우 분리 빔을 형성하기 위해서는 많은 연산량과 하드웨어 설계에 대한 고려가 있어야한다. 본 논문에서는 좌/우 분리 빔 형성을 위하여 주파수 빔 형성기법과 카디오이드 빔 형성기법을 합성하여 적용하였다. 주파수 빔 형성 기법은 짧은 수행시간 동안에 표적의 정보추출을 위하여 고려되었으며, 카디오이드 빔 형성기법은 3개의 센서를 이용하여 센서의 기울기를 보상하여 수행하는 기법을 적용하였다. 또한 방향성 있는 시뮬레이션 신호를 생성하여 좌/우 분리 빔 형성 시뮬레이션을 수행하였다.

• The Journal of the Acoustical Society of Korea
• /
• v.37 no.1
• /
• pp.66-72
• /
• 2018

In this paper, we propose an adaptive beamforming algorithm of triplet arrays for active sonar systems. The proposed algorithm consists of three steps: matched filters, cardioid beamforming, and line array beamforming. First, we apply a matched filter of a transmitted pulse to received individual sensor signals and obtain filterd signals. Then, we perform the fast Fourier transform to the matched filter results, and make a cardioid beam for each triplet data, respectively. Finally, we apply an adaptive beamforming by assuming that the cardioid beams are input signals of a line array. Experimental results demonstrate that the proposed algorithm provides better performances than conventional algorithms.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.6
• /
• pp.482-488
• /
• 2003

Line may receiver contains an ambiguity on conjugate bearings, because of lacking aperture in transverse direction. To solve the left/right bearing ambiguity of line-array receiver we used line-array with cardioid beam. In addition, the synthetic aperture method adopts coherent processing of sub-aperture signals at successive time intervals in the beam domain. We presented performances about division of left/right bearing ambiguity according to array synthetic number of times in this paper.