• Title/Summary/Keyword: 주파수 발생

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Integer Frequency Offset Estimation by Pilot Subset Selection for DRM+ Systems with CDD (순환 지연 다이버시티를 갖는 DRM+ 시스템에서 파일럿 집합 선택을 이용한 정수배 주파수 오차 추정 기법)

  • Kwon, Ki-Won;Cho, Yong-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.7C
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    • pp.481-487
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    • 2011
  • Cyclic delay diversity (CDD) is a simple transmit diversity technique for an OFDM system using multiple transmit antennas. However, the performance of post-FFT estimation, i.e., integer frequency offset (lFO) is deteriorated by high frequency selectivity introduced by CDD. In this paper, the IFO estimation scheme is proposed for OFDM-based DRM+ system with CDD. Based on the pilot subset partitioning, the proposed IFO estimation scheme reduces the effect of performance degradation caused by frequency selectivity in OFDM systems with CDD . The simulation results show that the performance of the proposed IFO estimator is significantly improved when compared to that of the conventional IFO estimator.

Speech and Music Discrimination Using Spectral Transition Rate (주파수 변화율을 이용한 음성과 음악의 구분)

  • Yang, Kyong-Chul;Bang, Yong-Chan;Cho, Sun-Ho;Yook, Dong-Suk
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.3
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    • pp.273-278
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    • 2009
  • In this paper, we propose the spectral transition rate (STR) as a novel feature for speech and music discrimination (SMD). We observed that the spectral peaks of speech signal are gradually changing due to coarticulation effect. However, the sound of musical instruments in general tends to keep the peak frequencies and energies unchanged for relatively long period of time compared to speech. The STR of speech is much higher than that of music. The experimental results show that the STR based SMD method outperforms a conventional method. Especially, the STR based SMD gives relatively fast output without any performance degradation.

Design of A 2-18GHz Digital Frequency Discriminator using Least-squares and Candidate-selection Methods (최소자승법과 후보군 선택 기법을 이용한 2-18GHz 디지털 주파수 변별기 설계)

  • Park, Jin Oh;Nam, Sang Won
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.6
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    • pp.246-253
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    • 2013
  • Based on the conventional 2-6GHz digital frequency discriminator (DFD) using the phase unwrapping and least-squares techniques, we propose a new 2-18GHz DFD. To compensate for lowered-precision frequency estimation due to the expanded bandwidth, the proposed DFD design employs more delay lines, accordingly accompanying high complexity. Thus, a new computationally efficient frequency estimation algorithm is also presented to overcome such high computational burden. More specifically, the proposed frequency estimation algorithm is basically based on the conventional phase unwrapping technique, along with a new candidates selection for the unwrapped phases under the condition that the phase margin is known. As a result, the computational burden required for the least-squares technique can be reduced. Finally, simulation results are provided to demonstrate the effectiveness of the proposed approach, compared with those of the conventional DFD's.

Speed estimation of sound-emitted objects through convergence of sound information analysis and smart device technology (음향 정보 분석과 스마트 기기 기술의 융합을 통한 사물의 속력 측정)

  • Nam, Yong-Wook;Kim, Yong-Hyuk
    • Journal of the Korea Convergence Society
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    • v.6 no.5
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    • pp.233-240
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    • 2015
  • In this paper, we present an algorithm that estimates the speed of a moving object only using its sound information. In general, the speed gun projects the incident light onto a moving object and measures the frequency variation of the scattered light. Then the speed is measured by this frequency difference. In our study, instead of light information, we measure the speed by sound frequency difference when the object is coming and moving away. In our experiments on the speed measurement, on average the error of 6.08% was obtained. Utilizing this algorithm for smart device, we can measure the speed of a moving object without sensor that measures the frequency of the light.

A Study on the Magnitude of the Noise and Frequency According to Materials for Soundproof Facilities of Tunnel (터널 방음시설의 방음재질 종류에 따른 소음과 주파수의 크기 고찰)

  • Won, Yeon-Ho;Cho, Young-Dong;Jeong, Jai-Hyung
    • Explosives and Blasting
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    • v.25 no.2
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    • pp.23-33
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    • 2007
  • It is difficult to measure a blast noise in the vicinity of tunnel blasting works and the effect of lowering noise changes very highly with types of soundproof materials. So, the main interest of this study focuses on the materials of a soundproof facilities and the method of noise forecast in a near distance. 20 types of the soundproof facilities are established and blast noise is generated using firecracker in a Hume concrete pipe. To analyze the variations of magnitudes of noise and frequency with the soundproof materials and types, the noise and frequency is measured in a short distance next to blast area.

Frequency Domain Scrambling Code Allocation for MC-CDMA Based Communication Systems (MC-CDMA 기반 통신 시스템을 위한 주파수 영역 스크램블링 부호 할당)

  • Kim, Houng-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.1A
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    • pp.44-50
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    • 2007
  • In typical MC-CDMA systems, different frequency-domain scrambling codes are randomly chosen from a given code set and then assigned to different subscriber stations using the same subcarrier set. When orthogonal codes are employed for the frequency-domain scrambling, the choice of the scrambling code does not affect the detection performance if the timing and frequency synchronizations are perfect and the channel characteristic is flat. However, in practical cases, inter-code interference often appears due to the broken code orthogonality. In this paper, the optimal order of allocating the orthogonal frequency-domain scrambling codes to new subscriber stations is derived under non-negligible timing offsets in MC-CDMA system.

A Simplified Digital Frequency/Phase/Voltage Controller for the Traveling Wave Type Ultrasonic Motor Drive System (초음파 모터 구동을 위한 단순화된 디지털 주파수/위상차/전압 제어기)

  • 이을재;김영석
    • The Transactions of the Korean Institute of Power Electronics
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    • v.4 no.3
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    • pp.285-293
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    • 1999
  • In this paper, the novel digital frequency/phase controller, to control the invelter fed traveling wave type ultra-sonic m motor(USM) is proposed. This controller is used to control the drive frequency, phase difference and applied voltages of e each phase of the motor. Proposed digital controller has constructed with digital logic only, no more use digitallongleftarrowanalog h hybrid method of the conventional controller, in order to generate drive frequency and phase difference. Therefore, the c control system has become to velY simple structure. T\rvo types of controllers are designed, one is to control drive f frequency and phase difference, another has added voltage control function of each phase. Two full digital voltage/phase c controllers are implemented by using custom LSI and EPLD, the control pelformance and the simplicity ofthe proposed c controller is verified by expeJimental results.

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Test Equipment and Test Portfolio for Education of Strain and Vibration Measurements (변형률 및 진동 측정 교육을 위한 실험 장치와 실험 포트폴리오)

  • Yang, Jimin;Lee, Dooyoul
    • Journal of Practical Engineering Education
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    • v.13 no.3
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    • pp.497-505
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    • 2021
  • Test equipment for strain and vibration measurement was designed for educational purposes. Widely available and affordable materials were put into making this device. Three strain gauges placed on an iron ruler made cantilevered beam were used to measure values according to external load. An electromagnet triggered excitation and a function generator created vibration of the beam. We present three different tests conducted with this equipment regarding production of scales, measurement of resonant frequency, and calculation of the difference between excitation frequency and measured frequency. Overall, this paper presents a piece of simple yet inexpensive test equipment and its corresponding portfolio with expectations of being applied to the educational field for efficient measurement of load and vibration.

Target Velocity Estimation Technique Using CPA Analysis at the Moving Receiver (CPA분석을 이용한 기동하는 수신기에서의 표적 속도 추정기법)

  • Lee, Su-Hyoung;Kim, Jeong-Soo;Lee, Kyun-Kyung
    • The Journal of the Acoustical Society of Korea
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    • v.28 no.4
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    • pp.336-342
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    • 2009
  • A conventional Closest Point of Approach (CPA) analysis allows a non-maneuvering moving source that is radiating a constant frequency tone to be located using doppler shifted frequency measurements obtained by a stationary receiver. The original frequency, relative speed of the target, time at the CPA, and range from the CPA to the sensor are estimated by the conventional CPA. However, this paper proposes a new CPA analysis that allows the motion parameters of a target to be estimated using the bearing and frequency measurements obtained by a moving receiver that has a constant velocity. The validity of the proposed estimation scheme is confirmed through a performance analysis and simulation study.

Recognizing multiple partial discharge sources by luavelet analysis (웨이블렛을 이용한 다중 부분방전 유무 판단기법)

  • Lee, Yang-Jin;Kim, Jae-Chul;Kim, Young-Sung;Cho, Sung-Min;Kim, Kwang-Hwa
    • Proceedings of the KIEE Conference
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    • 2006.05a
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    • pp.83-85
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    • 2006
  • 변압기 및 GIS 설비 내의 부분방전(Partial Discharge: PD) 발생 시 과도 UHF 신호들이 발생하고 그 신호들은 탱크 안에서 공진한다. 한 개 이상의 PD소스가 존재하고 간섭을 포함 할 때, PD에서 발생하는 본 신호들을 정확히 분류 할 수 있는 능력은 진단의 수준을 높일 것이다. 고속 푸리에 변환(FFT)은 주파수변화가 많을 시에, 주요 주파수의 특징 구별이 어렵다. 즉 푸리에 변환 적용 시 noise의 불규칙적인 파형으로 원 신호와의 구분이 어렵다. 그래서 시간과 주파수영역 모두에서 좋은 해상도를 나타내는 웨이블릿을 사용하였다. 변압기 및 GIS 설비 탱크에서 다른 위치의 PD소스로부터 UHF신호들을 인지하는 것에 대하여 웨이블렷에 기초된 방법은, 단지 한 개의 UHF 센서로 신호를 받았을 경우에도 묘사되어진다. UHF PD신호들의 시간-주파수 특성은 웨이블릿 변환으로부터 설립되고, 신호의 에너지 분포 mapping의 의미로 제공되어 진다. 유사함수(similarity function)는 다양한 웨이블릿 계수분포 사이에서 유사성의 측정을 제공하기 위하여 정의된다. 실험으로 측정된 데이터를 통하여 다중부분방전의 유무를 판단하고자 한다.

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