• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.473-476
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• 2017

As the society has developed into a digital information age society, a lot of electronic communication equipments are popularized. However, there are various causes of noise during signal transmission between communication devices. The noise generated in the communication system is a white noise that is distributed evenly in all frequency bands. This white noise causes system errors and lowers reliability. Therefore, in this paper, the existing Gaussian filter, Median filter, Alpha trimmed mean filter, and min/max filter for removing white noise are described and the characteristics and performance of each filter are compared with each other.

• The Journal of the Acoustical Society of Korea
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• v.12 no.1E
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• pp.5-11
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• 1993

본 논문에서는 페이딩 채널에서 백색 가우시안 잡음과 임펄스성 잡음이 부가된 디지털 신호를 복원하기 위하여 적응 LMS알고리즘과 RLS 알고리즘을 사용하여 TDL 등화기, 결정 궤환 등화기, 그리고 격자 등화기의 성능을 평가하고 비교하였다. 오차 성능 분석 결과, 페이딩이 존재하고 임펄스성과 가우스성 잡음이 존재하는 채널에서 10-3BER을 얻기 위해서, 격자 등화기는 LMS이 등화기보다 3.0dB, RLS TDL 등화기보다 3.9dB의 신호대 잡음비(SNR)여유를, 그리고 LMS DFE 등화기보다 0.5dB, RLS DFE등화기보다 -0.5dB의 SNR 여유를 갖음을 확인하였다.

• 전자공학회논문지 IE
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• v.49 no.2
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• pp.9-17
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• 2012

One of the problems on the application of the speech recognition system in the real world is the degradation of the performance by acoustical distortions. The most important source of acoustical distortion is the additive noise. This paper describes a spectral compensation technique based on a spectral peak enhancement scheme followed by an efficient noise subtraction scheme for noise robust speech recognition. The proposed methods emphasize the formant structure and compensate the spectral tilt of the speech spectrum while maintaining broad-bandwidth spectral components. The recognition experiments was conducted using noisy speech corrupted by white Gaussian noise, car noise, babble noise or subway noise. The new technique reduced the average error rate slightly under high SNR(Signal to Noise Ratio) environment, and significantly reduced the average error rate by 1/2 under low SNR(10 dB) environment when compared with the case of without spectral compensations.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.199-206
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• 2017

Environmental noise can degrade the performance of speech recognition system. This paper presents a procedure for performing cepstrum based feature compensation to make recognition system robust to noise. The approach is based on direct compensation of spectral tilt to remove effects of additive noise. The noise compensation scheme operates in the cepstral domain by means of calculating spectral tilt of the log power spectrum. Spectral compensation is applied in combination with SNR-dependent cepstral mean compensation. Experimental results, in the presence of white Gaussian noise, subway noise and car noise, show that the proposed compensation method achieves substantial improvements in recognition accuracy at various SNR's.

• Journal of IKEEE
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• v.11 no.4
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• pp.198-204
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• 2007

For parallel and serially concatenated trellis coded modulation (TCM), improved iterative decoding schemes with a simple mechanism are proposed and their performances are compared with those of conventional decoding schemes. Simulation results have shown that the proposed schemes have provided a considerable decoding gain in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels, even if they can be implemented by a simple modification of conventional decoding algorithms.

• ETRI Journal
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• v.9 no.3
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• pp.3-12
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• 1987

In this paper, a non-classical autocorrelation detector adopting a newly defined test statistic is introduced to solve the typical problem of detecting a narrowband signal transmitted over an additive white Gaussian noise (AWGN) channel. Error probability analyses are performed for a noncoherent frequency-shift-keying (FSK) system employing the proposed test-statistic. Through the histogram approach, the probability density functions of the test-statistics are plotted to explain the analysis model. All numerical results obtained indicate the limited improvement in error performance under the lower signal-to-noise ratio (SNR) and the use of higher number of samples per bit will finally provide the almost same confident potential of improvement in error rate as the system using matched filters (MFs) gives.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.821-827
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• 2014

This paper considers a distributed telemetry system using retransmission algorithm with one master telemetry and two slave telemetries. The master telemetry merges data from each slave telemetry and own measured data. If there exist some errors in data from the slave telemetry, the master telemetry requests retransmission to corresponding slave telemetry. In this paper, we propose a retransmission algorithm applied to implementing the distributed telemetry system. Simulation results demonstrate that the retransmission improves the performance of the communication between the master and slave telemetries.