• Title/Summary/Keyword: 대역폭 조절

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A Low-Voltage Low-Power Delta-Sigma Modulator for Cardiac Pacemaker Applications (심장박동 조절장치를 위한 저전압 저전력 델타 시그마 모듈레이터)

  • Chae, Young-Cheol;Lee, Jeong-Whan;Lee, In-Hee;Han, Gun-Hee
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.46 no.1
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    • pp.52-58
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    • 2009
  • A low voltage, low power delta-sigma modulator is proposed for cardiac pacemaker applications. A cascade of delta-sigma modulator stages that employ a feedforward topology has been used to implement a high-resolution oversampling ADC under the low supply. An inverter-based switched-capacitor circuit technique is used for low-voltage operation and ultra-low power consumption. An experimental prototype of the proposed circuit has been implemented in a $0.35-{\mu}m$ CMOS process, and it achieves 61-dB SNDR, 63-dB SNR, and 65-dB DR for a 120-Hz signal bandwidth at 7.6-kHz sampling frequency. The power consumption is only 280 nW at 1-V power supply.

Congestion Control Method of Area of Interest in Distributed Virtual Environment (분산가상환경에서 참여자 관심영역의 혼잡도 조절기법)

  • 유석종
    • Journal of Korea Multimedia Society
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    • v.7 no.4
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    • pp.550-558
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    • 2004
  • Previous researches on scalability problem of distributed virtual environment (DVE) have been mainly focused on spatial partitioning of area of interest (AOI). Congestion phenomena by avatar groups in AOI have been neglected relatively However, AOI congestion is highly related to scalability of DVE because it exhausts system resources such as network bandwidth and rendering time, and could be a bar to perform collaboration among participants. In this paper, this will be defined as the problem that must be solved for the realization of the scalable DVE, and a model will be proposed to measure and control congestion situation in AOI. The purposes of the proposed model are to prevent high density of participants in AOI, and to protect stable collaboration in DVE. For evaluation of the performance it is compared with a previous method by defining the resource cost model which is dynamically activated to AOI congestion.

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A Study on the Flow Control Mechanism based on RTP/RTCP for Real-Time Traffic Transmission (실시간 트래픽 전송을 위한 RTP/RTCP의 흐름제어 기법 연구)

  • Choi, Hyun-Ah;Song, Buk-Sub;Kim, Jeong-Ho
    • Proceedings of the Korea Contents Association Conference
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    • 2007.11a
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    • pp.60-64
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    • 2007
  • Increasing using multimedia services as VoIP, Video conference, DMB, IPTV, etc, it is necessary to increase network traffics and develop the mechanism about a flow control for real time traffic transmission. In order to transfer realtime multimedia data, the transfer rate can be control on network state data measuring packet losses of a receiver and delay time of packets through getting periodical feedback RTP/RTCP packet. This paper describes using efficiant flow control on multicast that can reduce errors according to getting feedback tranfer delay and proposes the mechanism that can adapt dynamic change of network. In simulation, the transfer rate can efficiently be control on dynamic change of network and it makes the maximum of the use of a bandwidth and the minimum of packet losses.

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Reference white setting based on brightness of CPT and resolution (수상관의 밝기 및 해상도를 고려한 기준 백색 설정)

  • 최덕규;김주동;권기룡;안상호;이건일;송규익
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.2
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    • pp.334-343
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    • 1997
  • Reference white in color television receiver can be achieved by adjusting the RGB gun current ratio and it is necessary to provide additional gain ratio adjustment for the RGB video signal. Generally, the gun current density profile has a gaussian distribution and the gain-bandwidth product of RGB channel amplifieris constant. Therefore brightness and spatial resolution are changed with variations in reference white of receiver. In this paper, the effect of RGB gun current and channel gain ratios on brightness and resolution of CPT is analyzed. Brightness is increased with the color temperature of referenc white because of Helmholtz-kohlrausch effect. The change in ligh output is more abrupt and spatial resolution is improved with unity current ratio. For more bright and improved ressolution we also present the range of color temperature of reference white for P22 phosphors.

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An HTTP Adaptive Streaming Scheme to Improve the QoE in a High Latency Network (높은 지연을 갖는 네트워크에서 QoE 향상을 위한 HTTP 적응적 스트리밍 기법)

  • Kim, Sangwook;Chung, Kwangsue
    • Journal of KIISE
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    • v.45 no.2
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    • pp.175-186
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    • 2018
  • Recently, HAS (HTTP Adaptive Streaming) has been the subject of much attention to improve the QoE (Quality of Experience). In a high latency network, HAS degrades the QoE due to the lost RTT cycle since it replies with a response of one segment to the request of one segment. The server-push based HAS schemes of downloading multiple segments in one request cause QoE degradation due to the buffer underflow. In this paper, we propose a VSSDS (Video Streaming Scheme based on Dynamic Server-push) scheme to improve the QoE in a high latency network. The proposed scheme adjust video quality by estimating available bandwidth and determine the number of segments to be downloaded for each segment request cycle. Through the simulation, the proposed scheme not only improves the average video bitrate but also alleviates the buffer underflow.

Design of the T-SRR and Low Loss Band-pass Filter Using MNG Metamaterial (MNG 메타 인공 물질을 이용한 T-SRR 및 저손실 대역통과 필터의 설계)

  • Yoon, Ki-Cheol;Kim, Seong-Cheol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.11
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    • pp.2512-2520
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    • 2013
  • In this paper, the T-SRR (Triple Split Ring Resonator) using MNG (mu-Negative) meta-material adapted in a low-loss bandpass filter with 3-stages is suggested. The size of the T-SRR in the proposed bandpass filter with low dielectric constant PCB can be easily controlled. And the ${\lambda}/4$ transmission line theory is applied. The proposed T-SRR and filter have the center frequency of 10 GHz with QL value of 184 for military-satellite communication system in I band. The experimental results of the filter show that the insertion and return losses are 1.44 dB and 17.3 dB with bandwidth of 10 %, respectively. The proposed filter will be redesigned by IPD material etc. should be placed here. These instructions give you guidelines for preparing papers for JICCE.

An Adaptive FEC based Error Control Algorithm for VoIP (VoIP를 위한 적응적 FEC 기반 에러 제어 알고리즘)

  • Choe, Tae-Uk;Jeong, Gi-Dong
    • The KIPS Transactions:PartC
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    • v.9C no.3
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    • pp.375-384
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    • 2002
  • In the current Internet, the QoS of interactive applications is hardly guaranteed because of variable bandwidth, packet loss and delay. Moreover, VoIP which is becoming an important part of the information infra-structure in these days, is susceptible to network packet loss and end-to-end delay. Therefore, it needs error control mechanisms in network level or application level. The FEC-based error control mechanisms are used for interactive audio application such as VoIP. The FEC sends a main information along with redundant information to recover the lost packets and adjusts redundant information depending on network conditions to reduce the bandwidth overhead. However, because most of the error control mechanisms do not consider end-to-end delay but packet loss rate, their performances are poor. In this paper, we propose a new error control algorithm, SCCRP, considering packet loss rate as well as end-to-end delay. Through experiments, we confirm that the SCCRP has a lower packet loss rate and a lower end-to-end delay after reconstruction.

Solitin Pulse Generation with Mode-Locked Erbium-Doped Fiber Laser Using Nonlinear Amplifying Loop Mirror (Nonlinear Amplifying Loop Mirror를 사용하여 모우드 록킹된 Erbium 첨가 광섬유 레이저에서 발생하는 솔리톤 펄스)

  • 박희갑;임경아
    • Korean Journal of Optics and Photonics
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    • v.6 no.2
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    • pp.142-147
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    • 1995
  • Soliton pulse outputs are generated with figure '8' type erbium-doped fiber laser mode-locked by using a fiber loop mirror. The fiber loop mirror consists of an erbium-doped fiber amplifier at the one end of the loop, and 504 m-long dispersion-shifted fiber as a nonlinear medium. By pumping with a $1.48{\mu}m$ wavelength laser diode and adjusting the polarization controllers inside the loop, soliton pulses are generated with 1574 nm center wavelength and 1.2 nm linewidth. The soliton pulses are found randomly spaced within the fundamental period corresponding to cavity round trip time. The autocorrelation trace shows that the pulse width is 2.4 ps, which is in good agreement with the theoretical prediction. The pulsewidth- bandwidth product is found to be 0.348 which means that the pulses are nearly transform-limited.imited.

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Design of Internal FM Radio Antenna for Mobile Terminal (휴대 단말기용 내장형 FM 라디오 안테나의 설계)

  • Han, Seung-Mok;Min, Kyeong-Sik
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.5
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    • pp.493-500
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    • 2008
  • This paper describes a design of internal frequency modulation(FM) radio antenna fur mobile terminal. In order to control of impedance at an operating frequency of the designed antenna, the lumped constant elements of R and L chip components are used. Patch and stubs located at antenna backside are added to control an exact resonance frequency and miniaturization. A fabricated antenna sire, the measured return loss, impedance, bandwidth, and gain are $40{\times}70{\times}1$ mm, -23 dB at 99 MHz, $55-j7{\Omega}$, 22 MHz($88{\sim}110$ MHz) below -10 dB, and -15 dBi, respectively. These measured results show a good agreement with simulated results. Especially, the measured gain of fabricated antenna is similar with value of a conventional ear-phone antenna in the designed frequency band. The measured radiation pattern agrees well with the calculated omni-directional pattern.

Wide Tuning and Modulation Characteristics Analysis of Coupled-Ring Reflector Laser Diode (결합 링 반사기 레이저 다이오드의 광대역 파장 가변 및 변조 특성 해석)

  • Yoon, Pil-Hwan;Kim, Su-Hyun;Chung, Young-Chul
    • Korean Journal of Optics and Photonics
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    • v.17 no.6
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    • pp.544-547
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    • 2006
  • A time-domain modeling approach is used to study characteristics of a widely tunable coupled-ring reflector (CRR) laser diode(LD). The CRR consists of a bus waveguide and two coupled ring resonators coupled to the bus without resorting to distributed Bragg grating structure. The tuning range can be a few tens of nanometers with a side mode suppression ratio exceeding 35dB through the adjustment of currents into the phase control sections in the rings. The CRR laser diode has long effective cavity length compared to conventional laser diodes. Accordingly, a broad additional resonance peak in the amplitude modulation characteristics is observed between 20 to 30 GHz, implying the extension of amplitude modulation bandwidth.