• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.257-260
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• 2001

In this paper, we propose a robust audio watermarking method. The proposed watermarking algorithm is composed of a psychoacoustic model to achieve perceptual transparency and spread spectrum technique to embed watermark. The watermark is embedded in each audio frame by adding a perceptually-shaped pseudo-random sequence. We demonstrate the robustness of the watermarking algorithm.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.569-572
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• 2000

본 논문에서는 DSSS(Direct Sequence Spread Spectrum)를 사용한 무선 감시용 카메라를 위한 모뎀을 제안한다 무선 환경에서 발생할 수 있는 여러 가지 간섭과 다중 경로에 의한 오류 발생 확률 등을 고려해야 하고 또한 여러 대의 카메라를 설치하고 각각의 카메라로부터의 신호를 선택적으로 모니터하기 위해 각각의 신호를 구분할 수 있는 변조 방식의 사용이 필요하다. 이를 위해 컴퓨터 모의 실험을 통한 성능 분석과 실제 FPGA설계 및 제작으로 이를 확인한다.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.837-840
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• 1987

In this paper, an MSK modulator and MSK matched Filter using SAW component which is small size and can process high Frequency and wide band signals are described. This modulator and matched Filter have been shown applicable to the transmitter and receiver of spread spectrum communication systems.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.112-114
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• 2009

In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.213-216
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• 2003

In this paper, we propose a digital watermarking method using the spread spectrum techniques in DCT domain. Watermark is embedded in the middle band frequencies of 8$\times$8 DCT block. Therefore, we improve image quality and robustness. Experiment results show that the proposed watermark is robust against various attack.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.7-10
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• 2003

본 논문에서는 중국의 광산에서 수행되고 있는 통신인 지하이동통신을 요약하여 설명하고, 이에 대한 문제점을 논의한다. 또한, 지하에서 스프레드 스펙트럼(spread spectrum) 통신이 장애에 강하고, CDMA가 사용하기에 용이하고 적합하다는 것을 제안한다. 그리고 중국 광산에서 사용되는 스프레드 스펙트럼 통신의 앞으로 전망을 설명하고 실행가능하고 실용적 인 프로그램을 제안한다.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.87-90
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• 2003

본 논문에서는 정현파를 이용한 spread-spectrum watermarking 에서 비가청성을 높이기 위한 방법과 효율적인 threshold 설정 방법을 제안한다. 제안하는 방법에서는 spread-spectrum 기법을 사용할 때 계산량이 많이 요구되는 심리음향모델 계산을 피하면서도 가청잡음을 줄이기 위한 방법을 제시한다. 또한 outlier 를 이용하여 워터마크 검출에서 적절한 threshold 설정방법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.453-460
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• 1988

The error probability for coherent frequency-hopped spread-spectrum multiple-access communications is computed by using characteristic function method. We employ PSK as a modulation scheme. The channel capacity is performance measure and the minimum bit signal-to-noise ratio for reliable communications is obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.1
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• pp.11-16
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• 1985

The performance analysis of serial search spread spectrum synchronization system is carried out. To evaluate the synchronization probabilities, two chi-square densities for signal plus noise and noise only are derived. Then Neyman-Pearson scheme is applied to determine the threshold of the synchronization system. The synchronization probability curves are shown as a function of threshold and signal to noise ratios.

• ETRI Journal
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• v.28 no.2
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• pp.250-252
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• 2006

In this letter, a discrete state, discrete time chaotic pseudo random number generator (CPRNG) is presented for stream ciphering of text, audio, or image data. The CPRNG is treated as a finite state machine, and its state is modulated according to the input bit sequence of the signal to be encrypted. The modulated state sequence obtained can be transmitted as a spread spectrum or encrypted data.