• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.1
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• pp.152-159
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• 2005

For high-speed data communication in band-limited channels, main of the bit error are fading and ISI(Inter-Symbol Interference). The common way of dealing with ISI is using equalization in the receiver. In this thesis, channel adaptive equalizer which uses Fuzzy Stochastic Gradient(FSG) and Constant Modulus Algorithm(CMA) is nonlinear equalizer, or Blind equalizer, that works directly on the signals with no training sequences required. This equalizer employs Takagi-Sugeno's fuzzy model that uses the FSG algorithm, to automatically regulate the step size of the descent gradient vector, combining fast convergence rate and low mean square error(MSE), and the CMA which is a special case of Godard's algorithm, to having multiple dispersion constants($R_p$).

• Journal of the Korean Professional Engineers Association
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• v.34 no.4
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• pp.30-35
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• 2001

The 8-VSB modulation technology developed by ATSC was adapted for national terrestrial DTV broadcasting. It uses same bandwidth of 6㎒ as the one of NTSC TV broadcasting. The simulcast on the both of analog and digital is mandated for some period, some shortage within the limited frequency resource . ATSC transmission technology is excellent in long distance broadcasting, but it is even poorer than other transmission technology In mobile receiving. The design of transmission system in the ATSC broadcasting is food enough with the provision of wide area service without Interference from adjacent channel. To provide adequate DTV service within the broadcasting area, transmission technology is an important factor

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.228-229
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• 2012

ATSC 지상파 DTV 방송은 8-VSB(Vestigial Sideband Modulation) 기반 단일 반송파 전송방식을 사용하기 때문에, 다중 경로에 의한 간섭에 취약한 단점이 있다. 다중경로에 의한 간섭은 DTV 수신기의 수신 성능을 열화시키기 때문에, 이러한 간섭을 효율적으로 등화하거나 또는 최소화되도록 방송망을 설계하는 것이 중요하다. 본 논문에서는 ATSC 지상파 DTV 방송 시스템에서 다중경로에 의한 간섭을 효율적으로 측정하는 방법을 제안하고, 모의실험을 통해 제안된 방법의 성능을 검증하고자 한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.380-380
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• 2004

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06b
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• pp.3-8
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• 1999

DTV(Digital Television)라 일컬어지는 방송 방식은 미국의 경우 지상파를 이용하여 압축된 영상신호와 음성신호를 방송 및 수신을 하기 위한 것으로 ATSC(Advanced Television System Committees)가 규격을 제안하고 FCC(Federal Communications Commission)가 수용하여 현실화 되어졌다. ATSC 산하의 다양한 Working Group에서는 방송국, 방송장비업체, 가전업체 등이 제안함으로써 규격화하여 전송부는 VSB(Vestigial Side-band), 영상압축은 MPEG2, 음성압축은 AC3로 결정하였다. 본 고에서는 ATSC의 규격에 따라 송신되어지는 방송을 수신할 수 있도록 채널복조와 영상 및 음성신호를 복호화 할 수 있는 수신 시스템의 구성과 테스트 결과를 살펴보고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.613-623
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• 2000

Digital TV tuner for 8-VSB modulation was developed with satisfying the requirements of ATSC. The double frequency conversion and the active tracking filter in the front-end were used to reduce interference of the adjacent channels and multi-channels, which suppress If beat and image band. However, it was impossible to get frequency mapping between tracking filter and first VCO(Voltage Controlled Oscillator) in the double conversion digital TV tuner differing from conventional NTSC tuner. This paper, therefore, suggests the available structure and a new method for automatic frequency selection by obtaining the mapping of frequency characteristic over tracking voltage and the combined hardware which compose of Micro-controller, EEPROM, D/A(Digital-to-Analog Converter), OP amp and switch driver to solve above problems.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.709-717
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• 2002

A new multi constant modulus algorithm (MCMA) for a blind decision feedback equalizer is proposed. In order to avoid the error propagation problem in the conventional DFE structure, Feed-Back Filter coefficients are updated only after Feed-Forward Filter coefficients are sufficiently converged to the steady state. Therefore, it has the problem of slow convergence speed characteristics. To overcome this drawback, the proposed MCMA algorithm uses not only new cost function considering the minimum distance between the received signal and the representative value containing the statistical characteristics of the transmitted signal, but also adaptive step-size according to the equalizer outputs to fast convergence speed of FBF. Simulations were carried out under the certified communication channel environment to evaluate a performance of the proposed equalizer. The simulation results show that the proposed equalizer has an improved convergence and SER performance compared with previous methods. The proposed techniques offer the possibility of practical equalization for cable modem and terrestrial HDTV broadcast (using 8-VSB or 64-QAM) applications.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.269-274
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• 2004

In this paper, proposed is the dual-mode algorithm of blind decision feedback equalizer (DFE) for digital terrestrial television signals. According to channel impairments, the proposed dual-mode algorithm for blind DFE operates in decision-directed mode or in blind mode of operation. The error signals being used in tap update of the equalizer are generated in the best mode of operations, so that the confidence of equalizer tap coefficient update is more accurate. As a result, it is possible to track the channel characteristics variations by automatic switching over between two modes of operations. For 8-level vestigial sideband modulated digital television signals, the mean square errors and symbol error rates of the proposed algorithm are compared with those of conventional methods. And the usability of the proposed scheme is assessed by computer simulations under various static and dynamic multipath channel environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.295-302
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• 2011

In this paper we consider technological requirements to broadcast digital television signals using single frequency networks(SFN) in the Advanced Television Systems Committee(ATSC) transmission systems and propose Interference Cancellation Digital On Channel Regenerative Repeater(IC-DOCR) thar overcomes the limitation of EDOCR(Equalization Digital On Channel Repeater) proposed by ETRI. The proposed IC-DOCR maintains the benefits of EDOCR that have good output signal quality removing multi-path, additive white Gaussian noise(AWGN). In additional, since the Interference Cancellation algorithm using the 8-VSB symbol demodulation of received signal removes the Interference of feedback signal, IC-DOCR improve the weakness of EDOCR that have low isolation between receive and transmit antenna so that can overcome the limitation of output signal power. we did analysis and verification of the proposed system performance using computational simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.351-363
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• 2006

The 8-VSB modulation, the transmission standard for the terrestrial digital television(DTV) of the Advanced Television Systems Committee(ATSC), suffers from multipath fading because it conveys information on the amplitude. To solve this problem, decision feedback equalizers(DFE's) have been commonly used in terrestrial DTV receivers. However, under severe channels, such as a 0 dB ghost channel or a single frequency network (SFN) channel, the DFE shows unstable convergence due to the error propagation caused by decision errors. Instead of unstable time-domain DFE schemes, by proposing a frequency-domain direct-inversion equalization method, we try to guarantee stable equalization and achieve low symbol error rates. To secure the existence of a channel inverse, channel-matched filtering and noncausal filtering are carried out prior to equalization. Simulation results show that the proposed method performs much better than existing DFE schemes in terms of both the stability and the symbol error rate.