• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.15-21
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• 2020

In this paper, the observation performance of the electro-optical telescope system which surveils the unknown space objects, is analyzed by the Modeling & Simulation(M&S). The operation concept for the observation of the unknown space objects using two telescope systems is considered and the M&S models are constructed. Based on the operation concept for observing the unknown space objects, the estimated orbit is generated by Initial Orbit Determination(IOD) and the observation performance is analyzed according to the offset compensation cycle for the estimated orbit. The result of the M&S based analysis in this paper shows that the observation performance increases with the shorter offset compensation cycle, and decreases with the longer offset compensation cycle. Therefore, to improve the performance of the telescope system which surveils the unknown space objects, the observation system with accurate initial orbit determination or shorter offset compensation cycle should be designed and constructed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.7
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• pp.30-38
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• 2012

This paper presents packet detection, frequency offset estimation architecture and performance analysis for OFDM-based wireless personal area network (WPAN) systems. Packet detection structure is used to find the start point of a packet exactly in WPAN system as the correlation value passes the constant threshold value. The applied autocorrelation structure of the algorithm can be implemented simply compared to conventional packet detection algorithms. The proposed frequency offset estimation architecture is designed for phase rotation process structure, internal bit reduction to reduce hardware size and the frequency offset adjustment block to reduce look-up table size unlike the conventional structure. If the received signal can be compensated by estimated frequency offset through the correction block, it can reduce the impact on the frequency offset. Through the performance result, the proposed structure has lower hardware complexity and gate count compared to the conventional structure. Thus, the proposed structure for OFDM-based WPAN systems can be applied to the initial synchronization process and high-speed low-power WPAN chips.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.469-471
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• 2022

This paper presents an implementation of a calibration circuit to correct the gain error, DC offset and sampling clock phase error generated in the process of converting digital pixels to analog pixels to drive an analog-driven 4K UHD LCOS panel. The proposed calibration circuit consists of a gain and DC offset adjustment circuit and a sampling clock phase adjustment circuit. The calibration circuit is implemented with an FPGA device, and video amplifiers.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.11a
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• pp.43-46
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• 2009

이 논문에서는 직교 주파수 분할 다중화(orthogonal frequency division multiplexing : OFDM) 시스템의 수신기에서 발생하는 다중 주파수 옵셋의 영향을 제거하는 방법을 제안한다. 다중 주파수 옵셋은 서로 다른 송신기로부터 동일한 신호를 수신할 때, 두 송신기의 발진 주파수가 서로 다르기 때문에 발생한다. 광대역 전송 시스템의 변복조 방식으로 널리 사용하고 있는 OFDM 방식은 대역효율이 높고 채널 추정이 간단하다는 장점이 있다. 그러나 OFDM 방식은 주파수 옵셋에 매우 민감 하다는 단점이 있다. 이 논문에서는 시간 영역에서의 1차적인 주파수 보정과 주파수 영역에서의 2차적인 채널간 간섭 제거방법을 적용하여 다중주파수 옵셋에 의한 영향을 효과적으로 제거하는 방법을 제안한다.

• Journal of Broadcast Engineering
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• v.15 no.2
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• pp.217-223
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• 2010

In this paper, an interchannel interference (ICI) cancellation method is proposed for multiple frequency offsets in orthogonal frequency division multiplexing (OFDM) systems. When several same signals are received from different transmitters simultaneously, multiple frequency offsets may occur at the receiver because of the frequency difference of the oscillators of the two transmitters and the receiver. This causes degradation of system performance because OFDM systems are very sensitive to the frequency offsets. In this paper, we propose a method to eliminate the effect of the multiple frequency offsets for OFDM systems. The method is accomplished in two steps: compensation of the frequency offset in the time domain and subsequent cancellation of the ICI in the frequency domain. Through computer simulations, we verify the effectiveness of the proposed ICI cancellation method.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.479-482
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• 2000

다중경로 채널의 시변 특성은 OFDM(orthogonal frequency division multiplexing) 신호의 직교성을 파괴시키며 이는 인접 채널간 간섭(ICI: interchannel interference)을 발생시켜 도플러 주파수에 비례하는 오류를 발생시킨다. 본 논문에서는 채널 시변의 원인을 주파수 옵셋과 도플러효과로 규정하고, 주파수 옵셋을 보정하기 위해 기존의 선형보간법(LI: linear interpolation method)대신 선형위상보간법(LPI: linear phase interpolation)과 도플러효과에 의한 ICI 를 제거하기 위해 기존의 주파수영역 등화기법보다 효과적인 시간영역 등화기법을 제안한다. 제안된 기법이 주파수 옵셋이 있는 시변 다중경로 페이딩 환경에서 OFDM 시스템에 적합함을 컴퓨터 모의실험을 통해 확인한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.11b
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• pp.161-165
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• 1999

다중경로 채널의 시변 특성은 OFDM(orthogonal frequency division multiplexing) 신호의 직교성을 파괴시키며 이는 인접 채널간 간섭(ICI: inter channel interference)을 발생시켜 도플러 주파수에 비례하는 오류를 발생시킨다. 본 논문에서는 채널 시변의 원인을 주파수 옵셋과 도플러효과로 규정하고, 주파수 옵셋을 보정하기 위해 기존의 선형보간법(LI: linear interpolation method)대신 선형위상보간법(LPI: linear phase interpolation)과 도플러효과에 의한 ICI를 제거하기 위해 기존의 주파수영역 둥화기법보다 효과적인 시간영역 등화기법을 제안한다. 제안된 기법이 주파수 옵셋이 있는 시변다중경로 페이딩 환경에서 OFDM 시스템에 적합함을 컴퓨터 모의실험을 통해 확인한다.

• Spatial Information Research
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• v.19 no.2
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• pp.19-28
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• 2011

Three dimensional modeling for seafloor topography is essential to monitoring displacements in underwater structures as well as all sorts of disasters along the shore. MBES is a system that is capable of high-density water depth measurement for seafloor topography and is in broad uses for gathering 3D data and detecting displacements. MBES data, however, contain random errors that take place in the equipment offset and surveying process and require systematic researches on the correction of wrong depth measurements. Thus this study set out to propose a post-processing technique to eliminate an array of random errors taking place after equipment offset correction and basic noise correction in the MBES system and analyze its applicability to seafloor topography modeling by applying it to the subject area.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4A
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• pp.247-255
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• 2003

In this paper, an $tan^{-1}$ circuit for the frequency synchronization of OFDM based IEEE 802.11a is presented. The proposed circuit consists of a divider, an $tan^{-1}$ ROM and a phase detector, which can detect frequency offset within 0.0491 rad. The circuit implemented with FPGA shows a pull-in range of under ${\pm}625KHz$ at 5dB AWGN. It may be useful for IEEE 802.11a WLAN standard.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.276-277
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• 2001

현재 컴퓨터 그래픽 분야에서 활동하는 전문 디자이너들은 WYSIWYG(What You See Is What You Get)을 지향하는 다양한 소프트웨어를 사용하고 있다. 그러나 이러한 소프트웨어들의 대부분은 디스플레이의 ${\gamma}$를 고려하여 색을 보정하도록 되어 있으므로, 시스템의 옵셋이 0이고 증폭률이 1이 되어 색 특성이 오로지 ${\gamma}$에 의존하는 최적상태로 조절된 디스플레이에 대해서만 정확한 보정이 이루어질 수 있다. (중략)