• Title/Summary/Keyword: 잡음전력스펙트럼

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Spectrum Sensing Scheme Using the Ratio of the Maximum and the Minimum of Power Spectrum (전력 스펙트럼의 최대 최소 비율을 이용한 스펙트럼 감지 방식)

  • Lim, Chang Heon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.6
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    • pp.3-8
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    • 2014
  • Recently, a spectrum sensing technique employing the maximum value of a received power spectrum as a test statistic has been presented in the literature for the purpose of detecting a wireless microphone signal in TV bands This detects the presence of a primary user by comparing the test statistic with some threshold, which depends on the background noise power level as well as a target false alarm rate. Therefore its performance may deteriorate when the noise power uncertainty occurs. As a means to mitigate this difficulty, we present a spectrum sensing strategy adopting the ratio of the maximum and the minimum value of the power spectrum as a test statistic and analyze its performance of spectrum sensing.

Voice Activity Detection Algorithm Based on the Power Spectral Deviation of Teager Energy in Noisy Environment (잡음환경에서 Teager 에너지의 전력 스펙트럼 편차에 기반한 음성 검출 알고리즘)

  • Park, Yun-Sik;An, Hong-Sub;Lee, Sang-Min
    • The Journal of the Acoustical Society of Korea
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    • v.30 no.7
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    • pp.396-401
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    • 2011
  • In this paper, we propose a novel voice activity detection (VAD) algorithm to effectively distinguish speech from nonspeech in various noisy environments. The presented VAD utilizes the power spectral deviation (PSD) based on Teager energy (TE) instead of the conventional PSD scheme to improve the performance of decision for speech segments. In addition, the speech absence probability (SAP) is derived in each frequency subband to modify the PSD for further VAD. Performances of the proposed VAD algorithm are evaluated by objective test under various environments and better results compared with the conventional methods are obtained.

Performance Analysis of an Energy Detection Based Cooperative Spectrum Sensing with a Single Threshold in the Presence of Noise Uncertainty (잡음 전력의 불확실성이 존재하는 환경에서 단일 임계값을 사용하는 에너지 검파 기반 협력 스펙트럼 감지의 성능 분석)

  • Lim, Chang Heon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.12
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    • pp.1406-1411
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    • 2012
  • An energy detection based spectrum sensing has been found to be vulnerable to the noise power uncertainty. A cooperative spectrum sensing with an energy detector has appeared as one of the solutions to alleviate this difficulty. However, its performance analysis in a fading environment has not been reported yet in the literature. Motivated by this, this paper presents the performance analysis of the scheme by extending our previous work on evaluating the performance of an energy detector in the presence of noise power uncertainty. The analysis shows that the false alarm probability and detection probability gets higher as the sensing time and/or the number of the secondary users in the OR based cooperative spectrum sensing scheme increase when the noise power uncertainty exists.

The Analysis of Channel Noise Characteristics for Power-Line Communication (PLC(Power-Line Communication)를 위한 채널 잡음 특성 분석)

  • 김정훈;김선효;이영철
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2001.05a
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    • pp.232-235
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    • 2001
  • 본 논문은 주파수 범위가 0∼30MHz에서 전력선 통신 채널상에 나타나는 잡음에 대한 실험적인 특성 및 수치계산에 의한 이론적인 근거를 전력선 채널 파라미터의 스펙트럼상의 잡음밀도 측정으로부터 유도하였으며, 거리에 따른 채널 모의실험을 통해서 나타난 잡음 특성을 이론적인 정보전달 범위에서 비교ㆍ분석하였다.

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Investigation on Frequency Spectral Characteristics in Switching Frequency Modulation Control (스위칭주파수 변조제어의 주파수 스펙트럼 특성 고찰)

  • 박석하;김양모
    • The Transactions of the Korean Institute of Power Electronics
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    • v.5 no.3
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    • pp.221-228
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    • 2000
  • 본 논문에서는 전기·전자 장비의 활용이 확대되면서 더욱 더 관심이 고조되고 있는 전자파장해에 대하여 논하고자 한다. 기존 PWM 직류전원장치에서는 회로 소자 및 배치에 따른 기생소자와 갑작스런 전압/전류의 변화에 의해 전자파장해를 발생시킨다. 본 논문에서는 PWM 직류전원장치에서 발생하는 전자파장해의 특성을 고찰하고, 출력전압 조절에 큰 영향을 주지 않는 범위내에서 PWM 제어가 가능하면서 두 개의 고정된 스위칭주파수로 연속적으로 변조하는 Bi-FM 변조제어방식과 랜덤하게 변화하는 스위칭주파수 변조제어방식을 이용하여 전도잡음을 저감시킬 수 있는 변조방식을 논할 것이다. 또한 이들 변조 방식의 주파수 스펙트럼 특성을 비교·분석하여 설명하고, 제어기를 분석·설계하여 실험을 통하여 스위칭주파수와 그 고조파 주파수들의 측대역으로 전도잡음이 분산되고 전도잡음의 피크치가 감소됨을 확인하고자 한다.

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Performance Analysis of an Energy Detection Based Cooperative Spectrum Sensing with Double Thresholds in the Presence of Noise Uncertainty (잡음 전력의 불확실성이 존재하는 환경에서 이중 임계값을 사용하는 에너지 검파 기반 협력 스펙트럼 감지의 성능 분석)

  • Lim, Chang Heon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.1
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    • pp.15-20
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    • 2013
  • An energy detection based spectrum sensing is widely known to be susceptible to the noise power uncertainty. As one of the methods to resolve this problem, a cooperative spectrum sensing based on an energy detector with double thresholds has been published recently. However, its performance analysis under a fading channel has not been carried out yet. In this paper, we present a closed form of performance analysis of the scheme by extending our previous work on evaluating the performance of an energy detector in the presence of noise power uncertainty.

Spectrum Based Detector in Non-white Noise Environment (비백색 잡음 환경에 적합한 스펙트럼 기반 탐지기)

  • Yu, Seog-Kun;Joo, Eon-Kyeong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.10
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    • pp.8-13
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    • 2009
  • The MF(matched filter) is the optimum signal detector that maximizes the output instantaneous signal power to average noise power ratio in white noise environment. But it cannot give the optimum detection performance if the background noise is not white. So, the whitening process preceding the matched filter is needed in the conventional detector which results in a PWMF(pre-whitening matched filter). Its performance is mainly affected by the estimation accuracy of non-white noise model which is used in the whitening procedure. To estimate more accurate model to improve performance, the computational complexity is increased. Therefore, a spectrum based detector which shows better performance than the PWMF under the similar complexity condition or less complexity under the similar performance condition is proposed in this paper. And its performance and complexity are analyzed and compared with the conventional PWMF.

Evaluation of Noise Power Spectrum Characteristics by Using Magnetic Resonance Imaging 3.0T (3.0T 자기공명영상을 이용한 잡음전력스펙트럼 특성 평가)

  • Min, Jung-Whan;Jeong, Hoi-Woun;Kim, Seung-Chul
    • Journal of radiological science and technology
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    • v.44 no.1
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    • pp.31-37
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    • 2021
  • This study aim of quantitative assessment of Noise Power Spectrum(NPS) and image characteristics of by acquired the optimal image for noise characteristics and quality assurance by using magnetic resonance imaging(MRI). MRI device was (MAGNETOM Vida 3.0T MRI; Siemense healthcare system; Germany) used and the head/neck shim MR receive coil were 20 channels coil and a diameter 200 mm hemisphere phantom. Frequency signal could be acquired the K-space trajectory image and white image for NPS. The T2 image highest quantitatively value for NPS finding of showed the best value of 0.026 based on the T2 frequency of 1.0 mm-1. The NPS acquired of showed that the T1 CE turbo image was 0.077, the T1 CE Conca2 turbo image was 0.056, T1 turbo image was 0.061, and the T1 Conca2 turbo image was 0.066. The assessment of NPS image characteristics of this study were to that could be used efficiently of the MRI and to present the quantitative evaluation methods and image noise characteristics of 3.0T MRI.

A New Unified System of Acoustic Echo and Noise Suppression Incorporating a Novel Noise Power Estimation (새로운 잡음전력 추정 기법을 적용한 음향학적 반향 및 배경잡음 제거 통합시스템)

  • Park, Yun-Sik;Chang, Joon-Hyuk
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.7
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    • pp.680-685
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    • 2009
  • In this paper, we propose a efficient noise power estimation technique for an integrated acoustic echo and noise suppression system in a frequency domain. The proposed method uses speech absence probability (SAP) derived from the microphone input signal as the smoothing parameter updating noise power to reduce the noise power estimation error resulted from the distortions in the unified structure where the noise suppression (NS) operation is placed after the acoustic echo suppression (AES) algorithm. Therefore, in the proposed approach, the smoothing parameter based on SAP derived from the input signal instead of echo-suppressed signal should stop updating noise power estimates during the distorted noise spectrum periods. The performance of the proposed algorithm is evaluated by the objective test under various environments and yields better results compared with the conventional scheme.

Design of Pulse Transceiver for Antipodal Ultra Wideband System (Antipodal 초광대역 통신 시스템의 변.복조기 설계)

  • Lee, Jung-Suk;Kim, Yoo-Chang;Kim, Won-Hoo
    • Proceedings of the Korea Information Processing Society Conference
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    • 2002.04b
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    • pp.1467-1470
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    • 2002
  • 한정된 주파수 문제를 해결하기 위해 제안된 초광대역 통신 시스템은 전 주파수 대역에 걸쳐 스펙트럼이 마치 기저 대역 잡음과 유사한 형태로 존재하여 타 통신 시스템에 간섭을 주지 않고 고속의 통신이 가능하며 반송파를 사용하지 않기 때문에 송 수신기의 소비 전력과 그 구조론 간략화 시킬 수 있다. 그러나 기존의 펄스 위치 방식(Pulse Positioning Modulation : PPM)은 주파수 스펙트럼 상에 불연속 전력 스펙트럼 성분이 존재하여 시스템의 효율을 저하된다. 본 논문에서는 불연속 전력 스펙트럼 성분이 발생하지 않고, 유클리드 거리가 최대가 될 수 있는 Antipodal 신호를 제안한다. 또한, 고주파 시뮬레이터인 Agilent 사의 Advanced Design System을 사용하여 Antipodal 신호를 이용한 변 복조기를 설계하여 구현 및 적용 가능성을 보였다.

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