• Title/Summary/Keyword: Frequency Estimation

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Parameter Estimation Method of Low-Frequency Oscillating Signals Using Discrete Fourier Transforms

  • Choi, Joon-Ho;Shim, Kwan-Shik;Nam, Hae-Kon;Lim, Young-Chul;Nam, Soon-Ryul
    • Journal of Electrical Engineering and Technology
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    • v.7 no.2
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    • pp.163-170
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    • 2012
  • This paper presents a DFT (Discrete Fourier Transform) based estimation algorithm for the parameters of a low-frequency oscillating signal. The proposed method estimates the parameters, i.e., the frequency, the damping factor, the mode amplitude, and the phase, by fitting a discrete Fourier spectrum with an exponentially damped cosine function. Parameter estimation algorithms that consider the spectrum leakage of the discrete Fourier spectrum are introduced. The multi-domain mode test functions are tested in order to verify the accuracy and efficiency of the proposed method. The results show that the proposed algorithms are highly applicable to the practical computation of low-frequency parameter estimations based on DFTs.

Frequency/Amplitude Separation Algorithm Using the Higher Order Differential Energy Operator and Its Application (고차의 미분에너지함수를 이용한 주파수 및 진폭성분 추출 알고리즘과 응용)

  • Iem, Byeong-Gwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.8
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    • pp.1498-1502
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    • 2007
  • There have been many different definitions of energy functions as the second statistics of a signal. In this paper, using the higher order differential energy function, we propose an algorithm separating the amplitude and frequency components in a discrete sinusoidal signal. The proposed amplitude and frequency estimation methods have less computational requirement than the existing methods. It also shows large computational advantage over the root mean square (RMS) calculation of a signal. The proposed methods can be used in the detection of abnormal events in signals on the power line. Computer simulations show that proposed frequency estimation method can detect the presence of voltage increase or decrease for a short period of time. Also, the proposed estimation methods have been compared with existing methods in terms of estimation error variance.

A Velocity-Adaptive Channel Estimation Scheme Using the Simple Zero-forcing Technique in the Frequency Domain (주파수 영역에서의 간단한 zero-forcing 기법을 이용한 속도 적응형 채널 추정 기법)

  • Yu Takki;Park Goohyun;Hong Daesik;Kang Changeon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.1A
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    • pp.38-47
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    • 2006
  • In this paper, we propose a velocity-adaptive channel estimation scheme using the simple zero-forcing technique in the frequency domain. Channel estimation is performed by removing frequency components that are higher than the maximum Doppler frequency in the received signal. The proposed scheme can be extended to the combined estimation scheme for channel coefficients and mobile velocity using one FFT/IFFT module. Simulation results show that the proposed scheme outperforms conventional schemes for a wide range of mobile velocities($3{\sim}300\;Km/h$). Finally, the MSE for the proposed channel estimation scheme is analyzed.

Joint Estimation Schemes of Carrier and Sampling Frequency Offsets for MB-OFDM UWB Systems (MB-OFDM UWB 시스템을 위한 반송파 및 샘플링 주파수 오프셋 결합 추정 기법)

  • Cho, Chang-Hoon;Yang, Suck-Chel;Shin, Yo-An
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.10C
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    • pp.965-975
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    • 2005
  • In this paper, we propose and evaluate joint carrier and sampling frequency offset estimation schemes based on the channel estimation sequences in PLCP (Physical Layer Convergence Procedure) preamble for the proper and effcient synchronization of the MB-OFDM WB (Multi-Band Orthogonal Frequency Division Multiplexing Ultra Wide Band) systems which have recently drawn explosive attention for future W-PAN (Wireless Personal Area Network) applications. In the joint estimation schemes, we first estimate the sampling frequency offset, and then estimate the carrier frequency offset using the estimated sampling frequency offset. Moreover, to improve the reliability of the estimated offset values, each process uses a combination scheme based on weighting factors. Simulation results using IEEE 802.15 Task Group 3a UWB channel models reveal that the estimation scheme using the simple weighting factors based on easily-measurable received signal power of each sub-channel shows favorably comparable performance to the ideal scheme using the weighting factors based on the perfectly-estimated frequency response of the channel.

A Comparative Study of Frequency Estimation Techniques using High Speed FIR Filter and Phasor Angle between Two Phasors (고속 FIR 필터와 두 페이저 위상을 이용한 주파수 추정 알고리즘의 비교 연구)

  • Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.2
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    • pp.122-129
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    • 2009
  • Frequency is an important operating parameter of a power system. It is essential that the frequency of a power system be maintained very close to its nominal frequency. And frequency measurement devices have need to measure a fast and accurate of frequency using voltage signals. This paper proposes a comparative study of frequency estimation techniques using the high speed FIR filter based algorithm, the DFT filter based algorithm using phasor angle between two phasors, and positive sequence component based algorithm using the half angle between two successive positions of phasor. The discussed three techniques have been formed through numerical manipulation of a discrete system. The proposed techniques have been tested using signals obtained from selected power system model using ATP simulation package. Some test results are shown in this paper.

Robust Pilot-aided Frequency Offset Estimation Scheme for OFDM-based Broadcasting System with Cyclic Delay Diversity

  • Shin, Won-Jae;You, Young-Hwan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.12
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    • pp.3055-3070
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    • 2013
  • This paper proposes an improved carrier frequency offset (CFO) and sampling frequency offset (SFO) estimation scheme for orthogonal frequency division multiplexing (OFDM) based broadcasting system with cyclic delay diversity (CDD) antenna. By exploiting a periodic nature of channel transfer function, cyclic delay and pilot pattern with a maximum channel power are carefully chosen, which helps to enable a robust estimation of CFO and SFO against the frequency selectivity of the channel. As a performance measure, a closed-form expression for the achievable mean square error of the proposed scheme is derived and is verified through simulations using the parameters of the digital radio mondiale standard. The comparison results show that the proposed frequency estimator is shown to benefit from properly selected delay parameter and pilot pattern, with a performance better than the existing estimator.

Development of Dynamic Frequency Monitoring Software for Wide-Area Protection Relaying Intelligence (광역 보호계전 지능화를 위한 동적 주파수 모니터링 S/W 개발)

  • Kim, Yoon-Sang;Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.4
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    • pp.174-179
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    • 2012
  • The social and economic level of damages might be highly increased in the case of wide-area black-outages, because of heavy dependence of electricity. Therefore, the development of a wide-area protection relay intelligence techniques is required to prevent massive power outages and minimize the impact strength at failure. The frequency monitoring and prediction for wide-area protection relaying intelligence has been considered as an important technology. In this paper, a network-based frequency monitoring system developed for wide-area protection relay intelligence is presented. In addition, conventional techniques for frequency estimation are compared, and a method for advanced frequency estimation and measurement to improve the precision is proposed. Finally, an integrated monitoring system called K-FNET(Korea-Frequency Monitoring Network) is implemented based on the GPS and various energy monitoring cases are studied.

Design of Efficient frequency Offset Estimator for MB-OFDM based UWB Systems (MB-OFDM 기반 UWB 시스템을 위한 효율적인 주파수 옵셋 추정기의 설계)

  • Kim, Kil-Hwan;Jung, Yun-Ho;Kim, Jae-Seok
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.3C
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    • pp.311-321
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    • 2009
  • This paper proposes an efficient frequency offset estimation algorithm for MB-OFDM based UWB systems. The time-frequency interleaving in MB-OFDM extends the time-interval between two transmitted OFDM symbols in the same sub-band. The extended time-interval causes not only the degradation of the system performance by reducing frequency offset estimation range, but also the increase of the hardware complexity by requiring the larger number of storing samples. The proposed estimation algorithm expands the estimation range by applying the proposed sign detection scheme. Simulation results show that the estimation range is increased above 30 ppm compared with a conventional auto-correlation based scheme. The estimation is performed on only one sub-band, and the frequency offsets of the others are calculated by relation to center frequency. This way reduced the number of the storing samples by about l/3. The frequency offset estimator with the proposed algorithm was designed into the architecture which minimizes hardware overhead by time-sharing operators and memory units, and which was synthesized to gate-level circuits using $0.13{\mu}m$ CMOS technology, and the total gates were about 47K.

Adaptive Suppression of Mechanical Resonance in High-Density Disk Drives (고밀도 디스크 드라이브의 적응형 공진 보상 알고리즘)

  • 강창익;김창환
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.9
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    • pp.679-691
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    • 2003
  • The band-width of disk drive servo system is rapidly increasing for the robustness to external disturbance as the track density is increasing. The increase of the band-width may cause mechanical resonance of an actuator. In disk drive servo system, a notch filter is usually used to suppress the mechanical resonance of the actuator. However, the resonance frequency differs from drive to drive because of manufacturing tolerance and varies with temperature even within a single drive. The variation of resonance frequency degrades the suppression performance of the notch filter. In this paper, we present an adaptive digital notch filter that identifies the resonance frequency of the disk drive servo actutaor precisely and adjusts automatically its center frequency. For this, we design an adaptive FIR digital filter for the estimation of the resonance frequency. The estimation filter identifies the resonance frequency adaptively using the output signal generated from the servo system, which is excited with an excitation signal including all the expected resonance frequency components. We prove mathematically the convergence of the resonance frequency estimation filter. Furthermore, in order to demonstrate the practical use of our work, we present some experimental results using a commercially available disk drive.

Sparse Channel Estimation of Single Carrier Frequency Division Multiple Access Based on Compressive Sensing

  • Zhong, Yuan-Hong;Huang, Zhi-Yong;Zhu, Bin;Wu, Hua
    • Journal of Information Processing Systems
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    • v.11 no.3
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    • pp.342-353
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    • 2015
  • It is widely accepted that single carrier frequency division multiple access (SC-FDMA) is an excellent candidate for broadband wireless systems. Channel estimation is one of the key challenges in SC-FDMA, since accurate channel estimation can significantly improve equalization at the receiver and, consequently, enhance the communication performances. In this paper, we study the application of compressive sensing for sparse channel estimation in a SC-FDMA system. By skillfully designing pilots, their patterns, and taking advantages of the sparsity of the channel impulse response, the proposed system realizes channel estimation at a low cost. Simulation results show that it can achieve significantly improved performance in a frequency selective fading sparse channel with fewer pilots.