• Title/Summary/Keyword: pulse shaping

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Bandwidth Efficient Digital Communication with Wavelet Approximations

  • Lo, Chet;Moon, Todd K.
    • Journal of Communications and Networks
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    • v.4 no.2
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    • pp.97-101
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    • 2002
  • Based on their shift and scale orthogonality properties, scaling and wavelet functions may be used as signaling functions having good frequency localization as determined by the fractional-out-of-band power (FOOBP). In this paper, application of Daubechies' wavelet and scaling functions as baseband signaling functions is described, with a focus on finding discretely realizable pulse-shaping transfer function circuits whose outputs approximate scaling and wavelet functions when driven by more conventional digital signaling waveforms. It is also shown that the inter-symbol interference (ISI) introduced by the approximation has negligible effect on the performance in terms of signal-to-noise ratio (SNR). Moreover, the approximations are often more bandwidth efficient than the original wavelet functions. These waveforms thus illustrate an example solution of a tradeoff between residual ISI and bandwidth efficiency as a signal design problem.

Magnetic Design of the KT-2 Tokamak for "Advanced Tokamak" Studies

  • Lee, Kwang-Won;B. G. Hong;S. R. In;J. M. Han;B. J. Yoon;Kim, S. K.;Lee, Jae-Koo;Kim, Dong-Eon;Y. K. Ra
    • Proceedings of the Korean Nuclear Society Conference
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    • 1995.05b
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    • pp.1033-1039
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    • 1995
  • The magnetic system design of the KT-2 tokamak has been performed at KAERI. Design goal has been set to facilitate the so-called "advanced tokamak" studies, which is essential to secure the economy of the tokamak fusion reactors. Design features include a large-aspect-ratio machine configuration, long-pulse operation capability with heavy plasma shaping, hybrid magnetic field control and machine/in-vacuum structures for MHD stability.

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Design and Simulation for the Filter of RFID System Operated at 13.56MHz (13.56MHz RF시스템에서의 필터 설계 및 시뮬레이션)

  • Ryu, Hyoung-Sun;Jin, In-Su;Yang, Gyung-Rock;Song, Seung-Ho;Kim, Yang-Mo
    • Proceedings of the KIEE Conference
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    • 2000.07d
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    • pp.3145-3147
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    • 2000
  • A passive RFID system consists of reader and tag. Reader is required the filter to modulate the data from backscattering signal which is transmitted by tag. The filter in the reader consists of envelope detector, amplifier, filter, and pulse shaping circuit, In this paper, design and analysis of filter in the RFID system which is operated at l3.56MHz carrier and 70KHz backscattering signal frequency is presented and is confirmed by simulation using Pspice.

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A Study on Linearization of Intermodulation Distortion for WCDMA

  • Jeon, Joong-Sung;Kim, Dong-il
    • Journal of Navigation and Port Research
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    • v.28 no.2
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    • pp.149-154
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    • 2004
  • A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth Experimental results are presented for IMT-2000 frequency band The center frequency of the feedforward amplifier is 2140MHz with 60MHz bandwidth When the average output power of feedforward amplifier is 20 Watt, the intermodulation cancellation performance is more than 28dB. In this case, the output power of feedforward amplifier reduced 3.5dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7% for multicarrier signals.

A new analysis on timing jitters in APD receivers of optical communication systems when considering intersymbol interferences (APD를 사용하는 광통신 시스템 수신기에서 심벌간 간섭을 고려할 경우 타이밍 지터에 대한 새로운 해석)

  • 신요안;은수정;김부균
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.3
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    • pp.539-546
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    • 1997
  • In this paper, we proposed a new mehtod to analyze the performance degradation by timing jitters in the APD (avalanche photodiode) receivers of intensity modulation/direct detection digital optical communication systems where raised cosine pulse-shaping filters are used to reduce the effect of noise while minimizing intersymbol interferences. The proposed analytical method is an extension of an analytical method we have already developed for pin diode receivers, and incorporates the effects of APD's multiplication factor and resulting shot noise. Using the proposed analytical method, we derive an approximated power penalty due to timing jitters based on an assumption of Gaussian distribution for timing jitters, and compare with that of the conventional analytical method. The results obtained from the proposed analytical method show that conventional analytical methods underestimate the influence of timing jitters on the reciver performance. The results also show that APD's multiplication factor which optimizes receiver sensitivity is smaller than that obtained by the conventional analytical method.

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Design and Performance Analysis of Non-coherent Code Tracking Loops for HSDPA MODEM (HSDPA 모뎀용 동기추적회로의 설계 및 성능분석)

  • Yang, Yeon-Sil;Park, Hyung-Rae
    • Journal of Advanced Navigation Technology
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    • v.7 no.1
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    • pp.6-13
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    • 2003
  • In this paper, a non-coherent code tracking loop is designed for 3GPP HSDPA MODEM and its performance is analyzed in terms of steady-state jitter variance and transient response characteristics. Analytical closed-form formula for steady-state jitter variance is first derived for AWGN environments as a function of pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth. Also obtained is the transient response characteristic of a tracking loop. Finally, the performance of the designed tracking loop is confirmed by computer simulations.

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Parameter estimation of weak space-based ADS-B signals using genetic algorithm

  • Tao, Feng;Jun, Liang
    • ETRI Journal
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    • v.43 no.2
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    • pp.324-331
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    • 2021
  • Space-based automatic dependent surveillance-broadcast (ADS-B) is an important emerging augmentation of existing ground-based ADS-B systems. In this paper, the problem of space-based ultra-long-range reception processing of ADS-B signals is described. We first introduce a header detection method for accurately determining the pulse position of a weak ADS-B signal. We designed a signal encoding method, shaping method, and fitness function. We then employed a genetic algorithm to perform high-precision frequency and phase estimations of the detected weak signal. The advantage of this algorithm is that it can simultaneously estimate the frequency and phase, meaning a direct coherent demodulation can be implemented. To address the computational complexity of the genetic algorithm, we improved the ratio algorithm for frequency estimation and raised the accuracy beyond that of the original ratio algorithm with only a slight increase in the computational complexity using relatively few sampling points.

ELECTROPHYSIOLOGICAL CHARACTERISTICS OF GABAERGIC INHIBITION IN THE HIPPOCAMPAL CA1 OF THE RAT IN VIVO (생체내 흰쥐 해마 CA1 세포에서 가바성 억제에 대한 전기생리학 특성)

  • Choi, Byung-Ju;Cho, Jin-Hwa;Kim, Young-Jin
    • Journal of the korean academy of Pediatric Dentistry
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    • v.27 no.1
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    • pp.7-14
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    • 2000
  • Inhibitory cells are critically involved in shaping normal hippocampal function and are thought to be important elements in the development of hippocampal pathologies. The present study was carried out in hippocampal CA1 area in vivo to compare with hippocampal slice studies. Intracellular and extracellular recordings with or without bicuculline electrodes were obtained in the intact brain of anesthetized rats, and cells were intracellularty labelled with neurobiotin. Electrical stimulation of fimbria-fornix resulted in an initial short-latency population spike. In the presence of $10{\mu}M$ bicuculline, orthodromic stimulation resulted in bursts of population spikes. The amplitude of population spikes in the CA1 region increased with stimulus intensity, as did the number of population spikes when the field recording electrode contained $10{\mu}M$ bicuculline. We measured the level of excitability in the CA1 area, using a paired-pulse stimulus paradigm to evoke population spikes. Population spikes showed strong paired-pulse inhibition at short interstimulus intervals. Burst afterdischarges up to 400 ms were observed after paired-pulse stimulus. These result suggest that hippocampal CA1 inhibitory interneurons can affect the excitability of pyramidal neurons that can not be appreciated in conventional in vitro preparation.

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A Study on the Curvilinearly Shaping Method for Wide-Band Wire Antennas (와이어 안테나의 광대역화를 위한 형상 굴곡화에 관한 연구)

  • Park, Eui-Joon;Lee, Young-Soon;Kim, Byung-Chul;Chung, Hoon;Cho, Jae-Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.3
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    • pp.454-463
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    • 2000
  • A method is presented to alter the geometry of the conventional linearly shaped wire antenna for increasing its bandwidth. The synthesis is two-demensionally symmetric and is based on the minimization of frequency-dependence of the boresight far-field electric field intensity. The current distribution on the wire is calculated by Galerkin method using pulse functions. The shaping limitation for wide-band characteristics is still found because of standing waves due to reflected waves from antenna ends. The limitation overcome by a distribution of resistive loads near ends of wire. The antenna loaded resistively has flat characteristics satisfying a power gain of $6.5\pm1.1$dBi and VSWR of at most 2 over 10:1 bandwidth. The results are verified by comparing with similar results for the conventional linear V-dipole.

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Several systems for 1Giga bit Modem

  • Park, Jin-Sung;Kang, Seong-Ho;Eom, Ki-Whan;Sosuke, Onodera;Yoichi, Sato
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1749-1753
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    • 2003
  • We proposed several systems for 1Giga bit Modem. The first, Binary ASK(Amplitude Shift Keying) system has a high speed shutter transmitter and no IF(Intermediate Frequency) receiver only by symbol synchronization. The advantage of proposed system is that circuitry is very simple without IF process. The disadvantage of proposed system are that line spectrum occurs interference to other channels, and enhancement to 4-level system is impossible due to its large SNR degradation. The second, Binary phase modulation system has a high speed shutter transmitter and IF-VCO(IF-Voltage Controlled Oscillator) control by base-band phase rotation. Polarity of shutter window is changed by the binary data. The window should be narrow same as above ASK. The advantage of proposed system is which error rate performance is superior. The disadvantage of proposed system are that Circuitry is more complex, narrow pull-in range of receiver caused by VCO and spectrum divergence by the non-linear amplifier. The third, 4-QAM(Quadrature Amplitude Modulation)system has a nyquist pulse transmitter and IF-VCO control by symbol clock. The advantage of proposed system are that signal frequency band is a half of 1GHz, reliable pull-in of VCO and possibility of double speed transmission(2Gbps) by keeping 1GHz frequency-band. The disadvantage of proposed system are that circuit complexity of pulse shaping and spectrum divergence by the non-linear amplifier.

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