• Title/Summary/Keyword: 신호 대 잡음 비율

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다구찌의 SN비와 BOX의 변수변환방법

  • 정은영;김지현
    • Communications for Statistical Applications and Methods
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    • v.3 no.2
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    • pp.85-91
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    • 1996
  • 일본의 품질 전문가 다구찌가 제안한 파라미터 설계의 장단점에 대해 많은 논의가 있어왔다. 본 연구에서는 신호 대 잡음 비율에 초점을 두어, 이론적 쟁점이 무엇인지를 요약하고, 그 문제점을 모의실험을 통해 구체적으로 지적하였다. 한편 신호 대 잡음 비율에 대한 대안 중에서 Box의 변수변환 방법을 소개하였다.

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Derivation of Asymptotic Formulas for the Signal-to-Noise Ratio of Mismatched Optimal Laplacian Quantizers (불일치된 최적 라플라스 양자기의 신호대잡음비 점근식의 유도)

  • Na, Sang-Sin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.5C
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    • pp.413-421
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    • 2008
  • The paper derives asymptotic formulas for the MSE distortion and the signal-to-noise ratio of a mismatched fixed-rate minimum MSE Laplacian quantizer. These closed-form formulas are expressed in terms of the number N of quantization points, the mean displacement $\mu$, and the ratio $\rho$ of the standard deviation of the source to that for which the quantizer is optimally designed. Numerical results show that the principal formula is accurate in that, for rate R=$log_2N{\geq}6$, it predicts signal-to-noise ratios within 1% of the true values for a wide range of $\mu$, and $\rho$. The new findings herein include the fact that, for heavy variance mismatch of ${\rho}>3/2$, the signal-to-noise ratio increases at the rate of $9/\rho$ dB/bit, which is slower than the usual 6 dB/bit, and the fact that an optimal uniform quantizer, though optimally designed, is slightly more than critically mismatched to the source. It is also found that signal-to-noise ratio loss due to $\mu$ is moderate. The derived formulas can be useful in quantization of speech or music signals, which are modeled well as Laplacian sources and have changing short-term variances.

Multihop Transmission in Cognitive Underlay Network Over Rayleigh Fading Channels (레일리 페이딩 채널에서 이상 인지 언더레이 네트워크 멀티 홉 전송)

  • Park, Sang-Young;Kong, Hyung-Yun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.6
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    • pp.291-296
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    • 2012
  • In this Paper, we propose a multi-hop transmission in cognitive underlay network. In Secondary network, We assume that a secondary source S attempts to transmit D its signal to a secondary destination via N+1 hops with help of N relays $R_1$, $R_2$, ${\ldots}$, $R_N$. At hop k between relay $R_k$ and relay $R_{k+1}$. we assume that there is a primary user $PU_k$. In this paper, we assume that these channels are Rayleigh fading channels. In underlay network, the secondary transmitter has to adapt its power so that the interference caused at the primary user is less than a maximum interference threshold. considering the hop transmission between the transmitter and the repeater, we find transmit power and signal-to-noise ratio(SNR). Between the transmitter from the receiver depending on the number of relay in the underlay network, we compared to find the transmit power and signal-to-noise ratio(SNR). Finally we find optimal number of relay and optimal threshold value.

Adaptive Multi-User Detection BISP Algorithm in DS/SS Communication (DS/SS 통신에서 BISP 알고리즘을 이용한 적응 다중 사용자 검출)

  • 석경휴;나기창;임영진;이성빈;배철수;나상동
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.142-146
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    • 2002
  • 직접 대역 확산 통신 방식에서 처리 이득에 비해 강한 협대역 간섭 신호가 존재 할 때 성능 향상을 위하여 다중 사용자 탐지 기술(MUD)을 사용하여 간섭 신호 제고를 위한 신호 검출을 하였으며, 적응 접속 채널 배열 응답과 다중 사용자 검출을 하기 위하여 BISP 알고리즘을 제안하였다. 또한 CDMA 채널에서 MAI와 ISI 검출에 BISP 알고리즘 신호 흐름 형태를 파악하여, 신호대 간섭 비율(SIR)과 신호대 잡음비율(SNR)에서 시간에 따른 비트율를 평가 하였다. 제안한 BISP 알고리즘은 방사 특성에 시간 지연 효율이 절반 이상 차이가 나지만 채널 특성 따라서 입력 신호를 조정 할 수 있다. 그리고 매치 필터를 통과하면서 각 채널간의 간섭을 억제하고, 사용자 검출을 용이하게 처리할 수 있다.

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Reducing the Effects of Wireless Optical Noise Using the Loss Characteristics of Plastic Fibers (플라스틱 광섬유의 손실 특성을 이용한 무선잡음광의 영향 감소)

  • Lee Seong-Ho
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.7 s.98
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    • pp.746-752
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    • 2005
  • In this paper, optical noise effect is reduced by using the loss characteristics of plastic fibers in an optical wireless system. The attenuation coefficient of a plastic fiber for the signal is different from that f3r the noise light, and the length difference between two fibers to the 2PD's behaves like a discriminative element. It is possible to eliminate the optical noise effect and detect only the signal without optical filters. The signal to noise ratio in a differential detector using fibers was 9.7 dB higher than in a single photodiode without optical fiber.

A Design of Noise Reduction Circuit for A radio Telephonic System (무선전화 시스템용 잡음억제회로의 설계)

  • Moon, Jong-Kyu;Kim, Duk-Gyoo
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.39 no.2
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    • pp.84-89
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    • 2002
  • In this paper, we present the design method of noise reduction circuit in telephonic system. The circuit consists of compressor, expander and a filter. The basic idea of a proposed method compresses the audible signal in order to mask the channel noise during transmission and then expand at the reverse rate the transmitted signal to naturally recover the original signal. Of course, there should be no distortion or other degradation of the audio itself in passing through companding(compress/expand) cycle. In the compressing process, the gain of compressor is automatically controlled by the envelope level of input signal in order to increase the effective dynamic range of input signal and to improve the signal to noise ratio. The compressed rate is the root time of a audible signal. The compressed signal should be expanded at the square time of the signal to recover a original signal. Simulation shows the proposed method improves the performance of the noise reduction of a channel noise as well as stability. 

PERFORMANCE & AMBIGUITY OF RANGE MEASUREMENT FOR COMS (통신해양기상위성의 위성 거리 측정 모호성 및 성능 분석)

  • Ahn, Sang-Il;Park, Dong-Chul
    • Journal of Astronomy and Space Sciences
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    • v.24 no.4
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    • pp.409-416
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    • 2007
  • The ambiguity and performance of range measurement for COMS using tone standard was analyzed with assuming that satellite is operating at transfer-station and on-station. From the results of analysis, it was shown that the ambiguity was reduced when low frequency ratio between tone signals and large number of minor tones are applied. It was also found that using the narrow noise bandwidth leads to decrease the ambiguity. As a result, required performance of range measurement for COMS can be satisfied when the noise bandwidth is set as 2Hz for transfer-station and 1Hz for on-station, respectively.

Estimation of Significant Wave Heights from X-Band Radar Using Artificial Neural Network (인공신경망을 이용한 X-Band 레이다 유의파고 추정)

  • Park, Jaeseong;Ahn, Kyungmo;Oh, Chanyeong;Chang, Yeon S.
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.6
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    • pp.561-568
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    • 2020
  • Wave measurements using X-band radar have many advantages compared to other wave gauges including wave-rider buoy, P-u-v gauge and Acoustic Doppler Current Profiler (ADCP), etc.. For example, radar system has no risk of loss/damage in bad weather conditions, low maintenance cost, and provides spatial distribution of waves from deep to shallow water. This paper presents new methods for estimating significant wave heights of X-band marine radar images using Artificial Neural Network (ANN). We compared the time series of estimated significant wave heights (Hs) using various estimation methods, such as signal-to-noise ratio (${\sqrt{SNR}}$), both and ${\sqrt{SNR}}$ the peak period (TP), and ANN with 3 parameters (${\sqrt{SNR}}$, TP, and Rval > k). The estimated significant wave heights of the X-band images were compared with wave measurement using ADCP(AWC: Acoustic Wave and Current Profiler) at Hujeong Beach, Uljin, Korea. Estimation of Hs using ANN with 3 parameters (${\sqrt{SNR}}$, TP, and Rval > k) yields best result.

A Study on Voice Activity Detection Using Auditory Scene and Periodic to Aperiodic Component Ratio in CASA System (CASA 시스템의 청각장면과 PAR를 이용한 음성 영역 검출에 관한 연구)

  • Kim, Jung-Ho;Ko, Hyung-Hwa;Kang, Chul-Ho
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.10
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    • pp.181-187
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    • 2013
  • When there are background noises or some people speaking at the same time, a human's auditory sense has the ability to listen the target speech signal with a specific purpose through Auditory Scene Analysis. The CASA system with human's auditory faculty system is able to segregate the speech. However, the performance of CASA system is reduced when the CASA system fails to determine the correct position of the speech. In order to correct the error in locating the speech on the CASA system, voice activity detection algorithm is proposed in this paper, which is a combined auditory scene analysis with PAR(Periodic to Aperiodic component Ratio). The experiments have been conducted to evaluate the performance of voice activity detection in environments of white noise and car noise with the change of SNR 15~0dB. In this paper, by comparing the existing algorithms (Pitch and Guoning Hu) with the proposed algorithm, the accuracy of the voice activity detection performance has been improved as the following: improvement of maximum 4% at SNR 15dB and maximum 34% at SNR 0dB for white noise and car noise, respectively.

Suboptimal Decision Fusion in Wireless Sensor Networks under Non-Gaussian Noise Channels (비가우시안 잡음 채널을 갖는 무선 센서 네트워크의 준 최적화 결정 융합에 관한 연구)

  • Park, Jin-Tae;Koo, In-Soo;Kim, Ki-Seon
    • Journal of Internet Computing and Services
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    • v.8 no.4
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    • pp.1-9
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    • 2007
  • Decision fusion in wireless sensor networks under non-Gaussian noise channels is studied. To consider the tail behavior noise distributions, we use a exponentially-tailed distribution as a wide class of noise distributions. Based on a canonical parallel fusion model with fading and noise channels, the likelihood ratio(LR) based fusion rule is considered as an optimal fusion rule under Neyman-Pearson criterion. With both high and low signal-to-noise ratio (SNR) approximation to the optimal rule, we obtain several suboptimal fusion rules. and we propose a simple fusion rule that provides robust detection performance with a minimum prior information, Performance evaluation for several fusion rules is peformed through simulation. Simulation results show the robustness of the Proposed simple fusion rule.

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