• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.97-104
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• 2004

As a channel of a DS-CDMA system is shared among several users, the receivers face the problem of MAI. Also the bandlimited channel leads to ISI. Both components are undesired, but unlike the additive noise process, which is usually completely unpredictable, their space-time structure helps to estimate and remove them. This paper investigates a DS-CDMA system with a fading multipath channel. The investigations have been separated into a channel estimation part and a reception part. In the estimation part of seperated two parts, the multipath parameters such as DOA and TOA are evaluated in this paper. In the part of receiver. we used these parameters and tested the performance of this receiver about space-time beamformers. To assess many different estimation techniques and beamformers, the simulation compared with theoretical values is performed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.928-933
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• 2008

본 연구에서는 최적 빔포머 (optimal beamformer)를 이용하여, 높은 지향특성을 갖는 라우드스피커 어레이를 구성하였다. 센서 어레이 시스템에 널리 적용되는 빔포밍 방법은 상반성 (reciprocity)의 원리에 의하여 라우드스피커 시스템에도 적용이 가능하다. 음원의 개수 및 배치 간격과 같은 최적 빔포머의 설계 변수와 지향성과의 관계를 살펴보고, 잡음 증폭을 억제하기 위해 적용되는 안정화 계수 (stability factor)도 유용한 설계 변수로 활용하였다. 또한 라우드스피커 자체가 갖는 지향성과 반사와 산란 등을 고려하여 빔포머를 최적화하는 방법을 제안하였고, 이 방법을 통해 예측치와 실제 시스템과의 차이를 줄였다. 실행 예제로 실제 어레이 시스템을 구성하고, 모의 실험과 실제 측정을 수행하여 성능을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.34-41
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• 2003

As a channel of a DS-CDMA system is shared among several users, the receivers face the problem of MAI. Also the bandlimited channel leads to ISI. Both components are undesired, but unlike the additive noise process, which is usually completely unpredictable, their space-time structure helps to estimate and remove them. This paper investigates a DS-CDMA system with a fading multipath channel. The investigations have been separated into a channel estimation part and a reception part. In the estimation part of seperated two parts, the multipath parameters such as DOA and TOA are evaluated in this paper. In the part of receiver, we used these parameters and tested the performance of this receiver about space-time beamformers(Decorrelating, Match-Filter, Wiener-Hopf, Subspace-Based). To assess many different estimation techniques and beamformers, the simulation compared with theoretical values is performed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.167-171
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• 2002

As a channel of a DS-CDMA system is shared among several users, the receivers face the problem of MAI. Also the multipath scenario leads to ISI. Both components are undesired, but unlike the additive noise process, which is usually completely unpredictable, their space-time structure helps to estimate and remove them. This paper investigates a DS-CDMA system with a fading multipath channel. The investigations have been separated into a channel estimation part and a reception part. In the first part, the estimation of multipath parameters(DOA, TOA) are considered, space-time beamformers(Decorrelating, Match-Filter, Wiener-Hopf) are performed in the second part. To assess many different estimation techniques and beamformers, the simulation compared with theoretical values is performed.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.193-196
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• 2003

시공간 빔포밍 기술은 기존의 배열 안테나가 공간만의 처리를 해온 것에 대하여 이를 시간 영역으로까지 확장하여 특정한 방향에서 특정한 시간에 도착하는 다중경로는 증폭하고 다른 다중경로는 제거하는 것을 의미한다. 본 논문은 배열 안테나를 가진 DS-CDMA에서 시스템 파라미터 부정합이 존재할 때, 시공간 빔 형성기의 성능에 대하여 연구하였다. 시뮬레이션 결과, 부정합이 존재할 때 전통적인 빔포머가 상대적으로 강인함을 보였지만 원근 문제는 해결할 수 없었으며, 실제의 추정 결과를 적용했을 때는 MUSIC 시공간 빔포머가 가장 우수한 성능을 보였다.

• Journal of Korea Society of Industrial Information Systems
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• v.24 no.1
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• pp.31-38
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• 2019

In this paper, we develop a beamforming front end platform with pipeline circuit configuration method that can apply various clinical diagnostic applications of ultrasound image technology. Hardware design targets compression applications as well as scalable applications where power, integration levels and replication possibilities are important. Firmware design was implemented to achieve optimal FPGA parallel processing level by constructing new IP and system-oriented design environment to accelerate design productivity with maximum productivity improvement using Vivado HLS tool, which is a next generation high level synthesis tool. Former supports the high-speed management function of scan data that can create an image area arbitrarily and can be appropriately corrected and supplemented when reconfiguring or changing system specifications in the future.

• The Journal of the Acoustical Society of Korea
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• v.41 no.5
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• pp.534-544
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• 2022

Medical ultrasound system has been widely used to visualize the lesion for diagnostics in most medical service site including hospitals and clinics thanks to its advantages such as real time operation, ease of use, safety. Among many signal processing blocks of the system, one of the most important part that governs the image quality is the beamformer, and technologies for this part has been continuously developed in long time. The synthetic aperture imaging method, that is one of the major technologies of beamforming, was introduced to maximize utilizing the information delivered from the patient's body through the probe, and contributed to breakthrough of the image quality since it was introduced in around 1990's, and evolved continuously in decades. This paper reviews and surveys the process of development of this technology and expects future evolution.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.766-767
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.128-129
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• 2010

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.43-47
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• 2024

This paper introduces a phased-array single-channel transceiver beamformer IC built using 65nm CMOS technology, covering the 8-16 GHz range and targeting the X and Ku bands for radar and satellite communications. Each signal path in the IC features a low noise amplifier (LNA), power amplifier (PA), phase shifter (PS), and variable gain amplifier (VGA), which allow for phase and gain adjustments essential for beam steering and tapering control in typical beamforming systems. Test results show that the phase-compensated VGA offers a gain range of 15 dB with 0.25 dB increments and an RMS gain error of 0.27 dB. The active vector modulator phase shifter delivers a 360° phase range with 2.8125° steps and an RMS phase error of 3.5°.