• Title/Summary/Keyword: Time Offset

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Novel Testing Method of CMOS Operation Amplifier using Offset Voltage (오프셋 전압을 이용한 CMOS 연산 증폭기의 새로운 테스팅 기법)

  • 한석붕;윤원효
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.507-510
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    • 1998
  • In this paper, a novel test method is proposed to detect hard and soft fault in CMOS operational amplifiers. Proposed test method mark use of the offset character, which is one of the op-amps characteristics. During the test mode, CUT is implemented to unit gain op-amps with feedback loop. When the input is grounded, a good circuit has a small offset voltage, but a faulty circuit has a large offset voltage exceeding predefined range of tolerance. Using the proposed method, no test vector is required to be applied. Therefore the test vector generation problem is eliminated and the test time is reduced. The accuracy and effectiveness of the method is verified through HSPICE simulation.

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BER Performance of the OFDM System with One-Tap Equalizer Bank under the Two-ray Multipath Channel with Frequency Offset (주파수 오프셋을 갖는 이중 경로 상에서의 One-Tap 등화기 뱅크를 갖는 OFDM 시스템의 BER 성능)

  • Hongku Kang;Wooncheol Hwang;Kim, Kiseon
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.51-54
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    • 1999
  • It is well known that the OFDM transmission is weak against the frequency offset. We evaluate the BER performance of the OFDM system with guard interval and simple one-tap equalizer bank. For the small frequency offset, the loss in $E_{b}$ $N_{o}$ is about 1㏈ at required BER = 10$^{-5}$ , when the mean value of the second-ray's attenuation coefficient is 0.25 and the normalized frequency offset, which is normalized about OFDM symbol time, is 5%.%.%.

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An Investigation on Heat transfer Characteristics of Inclined Wall Attaching Offest jet (경사진 벽부착 제트의 열전달 특성에 대한 연구)

  • 심재경
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.2
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    • pp.200-209
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    • 1998
  • Experiments have been conducted to determine heat transfer characteristics for a two-dimen-sional turbulent wall attaching offset jet at different oblique angles to a flat surface. The local Nusselt number distributions were measured using liquid crystal as a temperature sensor. Wall static pressure coefficient profiles were measured at the Reynolds number Re 53200(based on the nozzle width, D) the offset ratio H/D from 2.5 to 10 and the oblique angle a from $0^{\circ}$, to $40^{\circ}$ It is observed that the maximum Nusselt number point occurs slightly upstream of time-averaged reattachment point for all oblique angles. The correlations between the maximum Nusselt number and Reynolds number offset ration and oblique angle are presented.

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ML-Based Estimation Algorithm of Frequency Offset for $2{\times}2$ STBC-OFDM Systems

  • Lei, Ming;Zhao, Minjian;Zhong, Jie;Cai, Yunlong
    • ETRI Journal
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    • v.34 no.3
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    • pp.458-461
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    • 2012
  • In this letter, we propose a novel frequency offset estimation algorithm for space-time block code (STBC) orthogonal frequency division multiplexing systems. The algorithm mainly exploits the specific construction of STBC so that it does not need any additional pilots or sequences in the data field. The estimator is derived on the basis of the maximum likelihood theory. Simulation results show that this method can provide a significant performance improvement in terms of the estimation accuracy of the frequency offset.

A Robust OFDMA Channel Estimation Against Imperfect Synchronization (불완전 동기 환경에 강인한 OFDMA 채널 추정기법)

  • Chae Soo-Jin;Kim Eun-Ju;Kim Nak-Myeong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.8A
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    • pp.649-655
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    • 2005
  • We propose a robust channel estimation method against imperfect synchronization in orthogonal frequency division multiple access (OFDMA) downlink systems. We address time and frequency synchronization, and the channel estimation at the same time, and try to minimize the error propagation from the time and frequency synchronization steps into the chailnel estimation. The simulation results show that the proposed channel estimation method outperforms the conventional algorithms by about 3dB, and circumvents the problem of mismatch among the synchronization tasks.

Real-time Synchronization Algorithm for Industrial Hybrid Networks: CAN and Sensor Networks (공장 자동화용 혼합형 네트워크를 위한 실시간 동기화 알고리즘의 성능 분석: CAN과 센서 네트워크)

  • Jung, Ji-Won;Kim, Dong-Sung
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.2
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    • pp.194-201
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    • 2010
  • This paper discuss a performance evaluation of the synchronization algorithm for hybrid networks in industrial environments. The proposed algorithms minimizes synchronization errors which were caused from channel, Propagation, and frequency delays. The modified RBS and offset synchronization methods can be operated by adjustment parameters. The differential BP (Back-off Period) adjustment can synchronize the local time of each node with master node's time in hybrid networks. For the performance analysis, the data transmission time between the wired and wireless devices are investigated. The experimental results show the performance evaluations in terms of the polling service time and an average end-to-end delay.

Optimum Configuration of Single Frequency Network DMB to enhance the QoS and Service coverage (QoS 개선과 서비스 커버리지 확장을 위한 단일 주파수망 지상파 DMB 최적화 배치)

  • Cho, Young-Hun;Won, Chung-Ho;Seo, Jong-Soo
    • Journal of Broadcast Engineering
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    • v.19 no.4
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    • pp.439-452
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    • 2014
  • This paper suggests the method to extend service area by using the transmit offset delay in T-DMB single frequency network (SFN). In general, synchronization of the transmit time of all site can be done by using the reference clock of GPS, which dose not reflect the details geographical characteristics and transmit specifications of each site. Applying the site-specific transmit offset delay, we could extend the service area of SFN T-DMB. Applying the transmit offset delay, it is found that the signal quality in the region of weak receive field strength was improved and upto 4~8 km service area expansion was achieved by satisfying the minimum field strength ($45dB{\mu}V/m$) recommended by the Korea Communications Commission (KCC). Site-specific offset delay was calculated considering the geographic service area characteristics, distribution of electric field strength between neighboring sites and site-specific service target area. Experiments were carried out in order to analyze impact of calculated offset delay on the T-DMB SFN and also to confirm that the offset delay extends T-DMB service coverage. The experiment was done in metropolitan T-DMB service areas.

Convective heat transfer characteristics of a two-dimensional turbulent wall attaching offset jet (2차원 난류 벽부착제트의 대류열전달 특성)

  • Yun, Sun-Hyeon;Lee, Dae-Hui;Song, Heung-Bok;Kim, Dae-Seong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.10
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    • pp.3304-3312
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    • 1996
  • An experimental study on the convective heat transfer characteristics was performed for a two-dimensional wall attaching offset jet(WAOJ). Thermochromic liquid crystal was used to measure the plate wall temperature. The Nusselt number was measured for Reynolds numbers from 6, 500 to 39, 000, and the offset ratios from 0.5 to 15. The maximum Nusselt number point coincides with the time-averaged reattachment point and Nusselt number decreases monotonically after the jet reattaches on the wall. In the recirculation region Nusselt number minimize near the upstream corner and then increases as X/D decreases to vanishes. This suggests the existence of secondary vortices, causing an additional mixing of the flow in the corner. The correlations between the local Nusselt number and Reynolds number, Re, offset ratio, H/D, and streamwise distance, X/D are presented.

Flow Velocity Change of David Glacier, East Antarctica, from 2016 to 2020 Observed by Sentinel-1A SAR Offset Tracking Method

  • Moon, Jihyun;Cho, Yuri;Lee, Hoonyol
    • Korean Journal of Remote Sensing
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    • v.37 no.1
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    • pp.1-11
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    • 2021
  • This study measures the change of ice flow velocity of David Glacier, one of the fast-moving glaciers in East Antarctica that drains through Drygalski Ice Tongue. In order to effectively observe the rapid flow velocity, we applied the offset tracking technique to Sentinel-1A SAR images obtained from 2016 to 2020 with 36-day temporal baseline. The resulting velocity maps were averaged and the two relatively fast points (A1 and A2) were selected for further time-series analysis. The flow velocity increased during the Antarctic summer (around December to March) over the four years' observation period probably due to the ice surface melting and reduced friction on the ice bottom. Bedmap2 showed that the fast flow velocities at A1 and A2 are associated with a sharp decrease in the ice surface and bottom elevation so that ice volumetric cross-section narrows down and the crevasses are being created on the ice surface. The local maxima in standard deviation of ice velocity, S1 and S2, showed random temporal fluctuation due to the rotational ice swirls causing error in offset tracking method. It is suggested that more robust offset tracking method is necessary to incorporate rotational motion.

Development of a Frontal Collision Detection Algorithm Using Laser Scanners (레이져 스캐너를 이용한 전방 충돌 예측 알고리즘 개발)

  • Lee, Dong-Hwi;Han, Kwang-Jin;Cho, Sang-Min;Kim, Yong-Sun;Huh, Kun-Soo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.3
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    • pp.113-118
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    • 2012
  • Collision detection plays a key role in collision mitigation system. The malfunction of the collision mitigation system can result in another dangerous situation or unexpected feeling to driver and passenger. To prevent this situation, the collision time, offset, and collision decision should be determined from the appropriate collision detection algorithm. This study focuses on a method to determine the time to collision (TTC) and frontal offset (FO) between the ego vehicle and the target object. The path prediction method using the ego vehicle information is proposed to improve the accuracy of TTC and FO. The path prediction method utilizes the ego vehicle motion data for better prediction performance. The proposed algorithm is developed based on laser scanner. The performance of the proposed detection algorithm is validated in simulations and experiments.