• Title, Summary, Keyword: Time-multiplexing

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Feasibility study of multiplexing method using digital signal encoding technique

  • Kim, Kyu Bom;Leem, Hyun Tae;Chung, Yong Hyun;Shin, Han-Back
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2339-2345
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    • 2020
  • Radiation imaging systems consisting of a large number of channels greatly benefit from multiplexing methods to reduce the number of channels with minimizing the system complexity and development cost. In conventional pixelated radiation detector modules, such as anger logic, is used to reduce a large number of channels that transmit signals to a data acquisition system. However, these methods have limitations of electrical noise and distortion at the detector edge. To solve these problems, a multiplexing concept using a digital signal encoding technique based on a time delay method for signals from detectors was developed in this study. The digital encoding multiplexing (DEM) method was developed based on the time-over-threshold (ToT) method to provide more information including the activation time, position, and energy in one-bit line. This is the major advantage of the DEM method as compared with the traditional ToT method providing only energy information. The energy was measured and calibrated by the ToT method. The energy resolution and coincidence time resolution were observed as 16% and 2.4 ns, respectively, with DEM. The position was successfully distributed on each channel. This study demonstrated the feasibility that DEM was useful to reduce the number of detector channels.

Realization of Fractal/Angle Multiplexing using X-Y Galvano Mirrors and Evaluation of Random Access Performance in Holographic Digital Data Storage (X-Y 갈바노 미러를 이용한 홀로그래픽 저장 장치의 프랙탈/각 다중화 구현 및 임의 탐색 성능의 평가)

  • Choi, Jin-Young;Lee, Jae-Sung;Kim, Sang-Hoon;Kim, Jang-Hyun;Yang, Hyun-Seok;Park, No-Cheol;Park, Young-Pil;Park, Joo-Youn
    • Transactions of the Society of Information Storage Systems
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    • v.2 no.1
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    • pp.43-49
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    • 2006
  • Fractal/angle multiplexing is a $LiNBO_3$ crystal using a X-Y Galvano mirror, and the random access concept in fractal/angle multiplexing are discussed in this paper. First, the brief introduction of the designed holographic digital data storage system is presented. Then, the average access time concept for the storage system is newly defined, and the comparison of the average access time between the holographic storage and a conventional optical disk is performed. Second, the basic simulation and experiment to find the X-Y Galvano mirror dynamics are conducted. From this analysis, we find that the average access time in our HDDS which has 6 degree scan angle is about 5 msec. This result is very high performance when it compared with the average access time of a conventional optical disk. Finally, some recording results using fractal/angle multiplexing are presented, then, the relationship between bit error rate and angle mismatch for the each multiplexing are discussed.

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The exposure-time schedule for uniform diffraction efficiency in angle/fractal multiplexing of holographic data storage (홀로그래픽 저장장치의 각/프랙탈 다중화 방식에서 균일한 회절 효율을 위한 기록 시간 분배)

  • Lee, Jae-Sung;Choi, Jin-Young;Yang, Hyun-Seok;Park, Young-Pil;Park, No-Chul
    • 정보저장시스템학회:학술대회논문집
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    • pp.139-144
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    • 2005
  • Because of the photorefractive recording dynamics, each newly recorded hologram partially erases all previously stored image. Thus achieving the desired diffraction efficiency profile for the entire sequence after all images have been recorded requires exposure time schedule. The often cited classical exposure-schedule model predicts a rising-exponential build-up and an exponential decay in An with an exposure time. However because we cannot directly measure the An, it's difficult to establish the relation of both. In this paper, we deduce the relation of diffraction efficiency and exposure time from experiment data and suggest an algorithm to make time schedule profile in angle/fractal multiplexing of holographic data storage. After that, we present simulated result with equal hologram diffraction efficiency for a sequence of 250 holograms recorded by angle/fractal multiplexing.

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Time Domain Equalization for Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing을 위한 시간영역 등화기법)

  • Pyeon, Yong-Kug;Kang, Ki-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.54-57
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    • 2003
  • This study proposes that the Phase Linearization Interpolation is higher efficency than the existed Orthogonal Frequency Division Multiplexing system in the Multipath channels time-varient. Also, it showed that time domain equalization is better than the existed frequency domain equalization about the calculation and efficency for clear Inter Carrier Interference of the doppler effect.

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A Method to Compensate a Luminance Distortion of a Time-multiplexing Spatially Interlaced Stereoscopic Three-dimensional Display

  • Park, Minyoung;Choi, Hee-Jin
    • Current Optics and Photonics
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    • v.2 no.5
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    • pp.436-442
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    • 2018
  • In a spatially interlaced stereoscopic (SIS) three-dimensional (3D) display to be realized by providing the observer a part of left-eye/right-eye images, a loss of information can be perceived due to the un-shown part of each image. In order to resolve that problem, an improved SIS 3D display is proposed to deliver the images without loss of information to the observer using a time-multiplexing scheme. However, that time-multiplexing SIS also has a problem of luminance distortion when the desired luminance is not shown due to an insufficient response of the liquid crystal cell. In this paper, we propose a new method by optimizing the image data to show correct luminance with minimum distortion.

Reflection Signal Analysis for Time Division Multiplexing of Fiber Optic FBG Sensors (광섬유 FBG 센서의 시간 분할 다중화를 위한 반사 신호의 분석)

  • Kim, Geun-Jin;Kwon, Il-Bum;Yoon, Dong-Jin;Hwang, Du-Sun;Chung, Young-Joo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.1
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    • pp.6-12
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    • 2010
  • Fiber optic sensor using fiber Bragg grating(FBG) probes is used for monitoring strain and temperature distributed on the wide surfaces of large structures. In this paper, in order to use many FBG probes in one optical fiber line, we propose a complex multiplexing technology which is composed of two techniques, one is time division multiplexing and another is wavelength division multiplexing. However, we only investigate the characteristics of time division multiplexing because FBG sensors basically can be operated by wavelength division multiplexing. We calculate the optimal reflectivities and the lengthwise location of five FBG probes in serial connection in order to obtain the unique reflected intensities from the FBG probes. We fabricate five FBG probes with the reflectivities of 13%, 16%, 25%, 40% and 80%, which are determined by the theoretical calculation, and observe the signal reflected from each FBG in the time domain from the experiment. There are differences between experimental and theoretical results caused by the signal noise and the differences of reflectivities of FBG probes. But the experimental results shows the reflected signals of five FBG probes which prove the availability of complex multiplexing.

An Analysis on Multiplexing Gain vs. Variable Input Bit Rate Relation for Designing the ATM Multiplexer (ATM 멀티플렉서의 설계를 위한 다중화이득과 가변입력비트율과의 관계 해석)

  • 여재흥;임인칠
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.29A no.8
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    • pp.34-40
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    • 1992
  • This paper shows a new relational formula of multiplexing gain versus variable input bit rates useful for designing Nx1 ATM(Asynchronous Transfer Mode) multiplexer which mixes several asynchronous bit streams with different transmission rates. The relation between multiplexing gain and input bit stream speeds is derived from the occupied mean lenght(the width per unit time) of cells and the occupation probability of the number of cells at an arbitrary instant when the rates of the periodic cell strams change randomly. And the relation between multiplexing gain and variable bit rates from different number of input bit streams is analyzed accordingly. Under the condition of unlimited multiplexing speed, the more number of input bit streams increases, the bigger the multiplexing gain becomes. While for the case which restricts the multiplexing speed to a limited value, the multiplexing gain becomes smaller contrarily as the number of input bit streams continues too invrease beyond a boundary value. It is shown that for designing an ATM multiplexer according to the latter case, the combination of input bit streams should be determined such as its total bit rate is lower thean, but most apprpaximate to, the multiplexed output speed. Also the general formula evaluating the most significant parameters which should be needed to design the multiplexer is derived.

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New MAC Protocol for TWDM PON (TWDM PON을 위한 새로운 MAC 프로토콜)

  • Han, Man Soo;Na, Cheol Hun;Kang, Sung Jun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.741-742
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    • 2013
  • Passive optical networks (PONs) are the emerging solution for access networks since PONs provide high bandwidth. TDM ((time-division multiplexing) PON cannot support sufficient bandwidth for new broadband services such as UHD (ultra high-definition) IP TV, and VOD (video on demand). The solution is TWDM PON which is a mixture of WDM (wavelength-division multiplexing) and TDM. This paper proposes a new MAC (media access control) protocol for TWDM PON.

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New MAC Protocol and Dynamic Bandwidth Allocation Method for TWDM PON (TWDM PON을 위한 새로운 MAC 프로토콜 및 동적대역할당 방법)

  • Han, Man-Soo;Na, Cheol-Hun;Kang, Seong-Jun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.6
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    • pp.1419-1424
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    • 2013
  • Passive optical networks (PONs) are the emerging solution for access networks since PONs provide high bandwidth and the low operation cost. In recent, the new solution in access networks is TWDM PON which is a mixture of WDM (wavelength-division multiplexing) and TDM (time-division multiplexing). This paper proposes a new MAC (media access control) protocol for TWDM PON. In addition, this paper proposes and evaluates a new dynamic bandwidth allocation method for TWDM PON.

A Synchronized Multiplexing Scheme for Multi-view HD Video Transport System over IP Networks (실시간 다시점 고화질 비디오 전송 시스템을 위한 동기화된 다중화 기법)

  • Kim, Jong-Ryool;Kim, Jong-Won
    • Journal of Broadcast Engineering
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    • v.13 no.6
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    • pp.930-940
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    • 2008
  • This paper proposes a prototype realization of multi-view HD video transport system with synchronized multiplexing over IP networks. The proposed synchronized multiplexing considers the synchronization during video acquisition and the multiplexing for the interactive view-selection during transport. For the synchronized acquisition from multiple HDV camcorders through IEEE 1394 interface, we estimate the timeline differences among MPEG-2 compressed video streams by using global time of network between the cameras and a server and correct timelines of video streams by changing the time stamp of the MPEG-2 system stream. Also, we multiplex a selected number of acquired HD views at the MPEG-2 TS (transport stream) level for the interactive view-selection during transport. Thus, with the proposed synchronized multiplexing scheme, we can display synchronized HD view.