• Title/Summary/Keyword: Phase noise spectrum

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USBL Underwater Positioning Algorithm using Phase Spectrum (위상 스펙트럼에 의한 USBL 수중위치 추정기법 연구)

  • 이용곤;이상국;도경철
    • Journal of the Korea Institute of Military Science and Technology
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    • v.3 no.1
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    • pp.85-91
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    • 2000
  • Underwater sensor accuracy test which measures the detection range and bearing accuracies of sonar simulates sonar transmitting ping and underwater radiating noise of target vessels. In this test, because the position of sonar target is the reference position of test, the sonar target position should be precisely estimated. Hence, this paper suggests to apply USBL algorithm which adopts cross phase spectrum of received sensor signals, and presents its performance by range and bearing estimation simulations. As a result of simulations, suggested algorithm shows good accuracy for underwater sensor accuracy test near 5㏈ SNR.

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A Numerically Controlled Oscillator with a Fine Phase Tuner and a Rounding Processor

  • Lim, In-Gi;Kim, Whan-Woo
    • ETRI Journal
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    • v.26 no.6
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    • pp.657-660
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    • 2004
  • We propose a fine phase tuner and a rounding processor for a numerically controlled oscillator (NCO), yielding a reduced phase error in generating a digital sine waveform. By using the fine phase tuner presented in this paper, when the ratio of the desired sine wave frequency to the clock frequency is expressed as a fraction, an accurate adjustment in representing the fractional value can be achieved with simple hardware. In addition, the proposed rounding processor reduces the effects of phase truncation on the output spectrum. Logic simulation results of the NCO using these techniques show that the noise spectrum and mean square error (MSE) for eight output bits of a 3.125 MHz sine waveform are reduced by 8.68 dB and 5.5 dB, respectively, compared to those of the truncation method, and 2.38 dB and 0.83 dB, respectively, compared to those of Paul's scheme.

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Baleen Whale Sound Synthesis using a Modified Spectral Modeling (수정된 스펙트럴 모델링을 이용한 수염고래 소리 합성)

  • Jun, Hee-Sung;Dhar, Pranab K.;Kim, Cheol-Hong;Kim, Jong-Myon
    • The KIPS Transactions:PartB
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    • v.17B no.1
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    • pp.69-78
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    • 2010
  • Spectral modeling synthesis (SMS) has been used as a powerful tool for musical sound modeling. This technique considers a sound as a combination of a deterministic plus a stochastic component. The deterministic component is represented by the series of sinusoids that are described by amplitude, frequency, and phase functions and the stochastic component is represented by a series of magnitude spectrum envelopes that functions as a time varying filter excited by white noise. These representations make it possible for a synthesized sound to attain all the perceptual characteristics of the original sound. However, sometimes considerable phase variations occur in the deterministic component by using the conventional SMS for the complex sound such as whale sounds when the partial frequencies in successive frames differ. This is because it utilizes the calculated phase to synthesize deterministic component of the sound. As a result, it does not provide a good spectrum matching between original and synthesized spectrum in higher frequency region. To overcome this problem, we propose a modified SMS that provides good spectrum matching of original and synthesized sound by calculating complex residual spectrum in frequency domain and utilizing original phase information to synthesize the deterministic component of the sound. Analysis and simulation results for synthesizing whale sounds suggest that the proposed method is comparable to the conventional SMS in both time and frequency domain. However, the proposed method outperforms the SMS in better spectrum matching.

Performance Analysis of OFDM Communication System with the IQ Imbalance and Phase Noise (IQ Imbalance와 위상 잡음을 고려한 OFDM 통신 시스템의 성능 분석)

  • Kim, Sang-Kyun;Ryu, Heung-Gyoon;Kang, Byung-Su;Lee, Kwang-Chun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.7
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    • pp.757-765
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    • 2007
  • OFDM system is an excellent high speed transmission method but it is seriously sensitive to the phase noise and IQ imbalance. Therefore, in this paper, we analyze the communication performance of the OFDM communication system with IQ imbalance and phase noise. Phase noise's variance can be calculated by integral calculus of phase noise power spectrum. From simulation results, it can be shown that the BER performances show different change according to the phase noise variance and IQ imbalance amount. When amplitude imbalance is ${\varepsilon}$=0.2; 0.3; 0.4 and phase imbalance is ${\phi}=10^0$, and distribution of phase noise is ${\sigma}^2=0.012$, BER is degraded by 2.88 dB, 3.61 dB, 4.09 dB in $10^{-5}$ in the respect of the SNR penalty.

Numerical Analysis on the Low Noise Designs of Savonius Wind Turbines by Inducing Phase Difference in Vortex Shedding (와류이탈 위상차를 이용한 사보니우스형 풍력터빈의 소음 저감 설계에 관한 수치적 연구)

  • Kim, Sanghyeon;Cheong, Cheolung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.3
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    • pp.269-274
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    • 2014
  • In this study, low noise designs for a Savonius wind turbine were numerically investigated. As was reported in our previous study, the harmonic components with a fundamental frequency higher than the BPF were identified as being dominant in the noise spectrum of a Savonius wind turbine, and these components were a result of vortex shedding. On a basis of this observation, an S-shaped blade tip is proposed as a means of reducing the noise generated by small vertical(Savonius) wind turbines. This blade induces phase differences in the shedding vortices from the blades, and thus reduces the noise from the wind turbine. The aerodynamic noise characteristics of the conventional and "S-shaped" Savonius turbines were investigated by using the Hybrid CAA method where the flow field around the turbine is computed using the CFD techniques and the radiated noise are predicted by applying acoustic analogy to the computed flow field data. The degree of noise reduction resulting from the proposed design and its reduction mechanism were confirmed by comparing the predicted noise spectrum of these turbines and the flow characteristics around them.

Speckle Noise Reduction and Image Quality Improvement in U-net-based Phase Holograms in BL-ASM (BL-ASM에서 U-net 기반 위상 홀로그램의 스펙클 노이즈 감소와 이미지 품질 향상)

  • Oh-Seung Nam;Ki-Chul Kwon;Jong-Rae Jeong;Kwon-Yeon Lee;Nam Kim
    • Korean Journal of Optics and Photonics
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    • v.34 no.5
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    • pp.192-201
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    • 2023
  • The band-limited angular spectrum method (BL-ASM) causes aliasing errors due to spatial frequency control problems. In this paper, a sampling interval adjustment technique for phase holograms and a technique for reducing speckle noise and improving image quality using a deep-learningbased U-net model are proposed. With the proposed technique, speckle noise is reduced by first calculating the sampling factor and controlling the spatial frequency by adjusting the sampling interval so that aliasing errors can be removed in a wide range of propagation. The next step is to improve the quality of the reconstructed image by learning the phase hologram to which the deep learning model is applied. In the S/W simulation of various sample images, it was confirmed that the peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) were improved by 5% and 0.14% on average, compared with the existing BL-ASM.

A Study on PLL Design for Ultra Wideband (초 광대역용 PLL 설계에 관한 연구)

  • Lee, Yong-Woo;Lee, Il-Kyoo;Oh, Seung-Hyeub
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.4
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    • pp.193-198
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    • 2010
  • In this paper, we have introduced a new way to have low phase noise PLL of the Ultra wideband to meet performance requirements. Before development of the PLL, we simulated spectrum power, phase noise by using ADS. Finally, we confirm a satisfying result between required standard and measured value.

The Identification of Generation Mechanism of Noise and Vibrtaion and Transmission Characteristics for Engine System - The Source Identification and Noise Reduction of Compartment by Multidimensional Spectral Analysis and Vector Synthesis Method - (엔진의 소음.진동발생기구 및 전달특성 규명 -다차원해석법과 벡터합성법에 의한 차실소음원 규명 및 소음저감 -)

  • O, Jae-Eung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.7
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    • pp.1127-1140
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    • 1997
  • With the study for identifying the transmission characteristics of vibration and noise generated by operating engine system of a vehicle, recently many engineers have studied actively the reduction of vibration and noise inducing uncomfortableness to the passenger. In this study, output noise was analyzed by multi-dimensional spectral analysis and vector synthesis method. The multi-dimensional analysis method is very effective in case of identification of primary source, but this method has little effect on suggestion for interior noised reduction. For compensation of this, vector synthesis method was used to obtain effective method for interior noise reduction, after identifying primary source for output noise. In this paper, partial coherence function of each input was calculated to know which input was most coherent to output noise, then with simulation of changes for input magnitude and phase by vector synthesis diagram, the trends of synthesized output vector was obtained. As a result, the change of synthesized output vector could be estimated.

Error Probability of a Hybrid DS/SFH Spread-Spectrum System under Tone Jamming (Tone 신호방해 하에서의 DS/SFH 복합 확산대역 시스템의 비트오율)

  • 유병석;이재홍;이상철
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.5
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    • pp.645-655
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    • 1990
  • A hybrid DS/SFH spread spectrum system is used to achieve a larger gain in some applications. The probability of error for a hybrid DS/SFH(direct sequence/slow frequency hopped) spread-spectrum system is calculated over a channel which suffers from multiple-tone jamming and additive white Gaussian noise. BPSK(binary phase shift keying) is considered as modulation scheme. The probability of error is computed for various system parameters such as a DS/SFH hybrid ratio, the number of jamming tones, a jamming-to-signal ratio, and a siganl-to-noise ratio. It is shown that a DS system or a SFH system achieves smaller probability of error than a hybrid DS/SFH system for most values of system parameters. However, it is also shown that there are hybrid ratios with which a hybrid DS/SFH system achieves smaller probability of error than a DS system and a SFH system achieve for some values of system parameters.

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A study on speech enhancement using complex-valued spectrum employing Feature map Dependent attention gate (특징 맵 중요도 기반 어텐션을 적용한 복소 스펙트럼 기반 음성 향상에 관한 연구)

  • Jaehee Jung;Wooil Kim
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.6
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    • pp.544-551
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    • 2023
  • Speech enhancement used to improve the perceptual quality and intelligibility of noise speech has been studied as a method using a complex-valued spectrum that can improve both magnitude and phase in a method using a magnitude spectrum. In this paper, a study was conducted on how to apply attention mechanism to complex-valued spectrum-based speech enhancement systems to further improve the intelligibility and quality of noise speech. The attention is performed based on additive attention and allows the attention weight to be calculated in consideration of the complex-valued spectrum. In addition, the global average pooling was used to consider the importance of the feature map. Complex-valued spectrum-based speech enhancement was performed based on the Deep Complex U-Net (DCUNET) model, and additive attention was conducted based on the proposed method in the Attention U-Net model. The results of the experiments on noise speech in a living room environment showed that the proposed method is improved performance over the baseline model according to evaluation metrics such as Source to Distortion Ratio (SDR), Perceptual Evaluation of Speech Quality (PESQ), and Short Time Object Intelligence (STOI), and consistently improved performance across various background noise environments and low Signal-to-Noise Ratio (SNR) conditions. Through this, the proposed speech enhancement system demonstrated its effectiveness in improving the intelligibility and quality of noisy speech.