• Title, Summary, Keyword: Doppler

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Ocean Surface Current Retrieval Using Doppler Centroid of ERS-1 Raw SAR Data

  • Kim Ji-Eun;Kim Duk-jin;Moon Wooil M.
    • Proceedings of the KSRS Conference
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    • pp.590-593
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    • 2004
  • Extraction of ocean surface current velocity offers important physical oceanographic parameters especially on understanding ocean environment. Although Remote Sensing techniques were highly developed, the investigation of ocean surface current using Synthetic Aperture Radar (SAR) is not an easy task. This paper presents the results of ocean surface current observation using Doppler Centroid of ERS-1 SAR data obtained off the coast of Korea peninsula. We employed the concept, in which Doppler frequency shift and the ocean surface current are closely related, to evaluate ocean surface current. Moving targets cause Doppler frequency shift of the back scattered radar waves of SAR, thus the line-of-sight velocity component of the scatters can be evaluated. The Doppler frequency shift can be measured by estimating the difference between Doppler Centroid of raw SAR data and reference Doppler Centroid. Theoretically, the Doppler Centroid is zero; however, squinted antenna which is affected by several physical factors causes Doppler Centroid to be nonzero. The reference Doppler Centroid can be obtained from measurements of sensor trajectory, attitude and Earth model. The estimated Doppler Centroid was compensated by considering the accurate attitude estimation of ERS-1 SAR. We could verify the correspondence between the estimated ocean surface current and observed in-situ data in the error bound.

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Development of Portable Arrhythmia Moniter Using Microcomputer(I) (마이크로 컴퓨터를 이용한 휴대용 부정맥 모니터의 개발(I)-하드웨어 설계를 중심으로-)

  • 이명호;안재봉
    • Journal of Biomedical Engineering Research
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    • v.7 no.2
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    • pp.169-182
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    • 1986
  • Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood-flow-velocity, velocity profile, and volume-blood-flow. This system is more powerful compare with 2-dimensional B-scan tissue image. A system has been deve- loped and ii being evaluated using TMS 32010 DSP. We use this DSP for the purpose of real-time spectrum analyzer to obtain spectrogram in singlegate pulsed Doppler system and for the serial comb filter to cancel clutter and zero crossing counter to estimate Doppler mean frequency in multigate pulsed Doppler system. The Doppler shift of the backscattered signals is sensed in a phase detector. This Doppler signal corresponds to the mean velocity over a some region in space defined by the ultrasonic beam dimensions, transmitted pulse duration, and transducer ban(iwidth. Multi- gate pulsed Doppler system enable the transcutaneous and simultaneous assessment of the velocities in a number of adjacent sample volumes as a continuous function of time. A multigate pulsed Doppler system processing the information originating from presented.

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Development of Ultrasound Sector B-Scanner(III)-Pulsed Ultrasonic Doppler System- (초음파 섹터 B-스캐너의 개발(III)-초음파 펄스 도플러 장치-)

  • 백광렬;안영복
    • Journal of Biomedical Engineering Research
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    • v.7 no.2
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    • pp.139-146
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    • 1986
  • Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood-flow-velocity, velocity profile, and volume-blood-flow. This system is more powerful compare with 2-dimensional B-scan tissue image. A system has been deve- loped and ii being evaluated using TMS 32010 DSP. We use this DSP for the purpose of real-time spectrum analyzer to obtain spectrogram in singlegate pulsed Doppler system and for the serial comb filter to cancel clutter and zero crossing counter to estimate Doppler mean frequency in multigate pulsed Doppler system. The Doppler shift of the backscattered signals is sensed in a phase detector. This Doppler signal corresponds to the mean velocity over a some region in space defined by the ultrasonic beam dimensions, transmitted pulse duration, and transducer ban(iwidth. Multi- gate pulsed Doppler system enable the transcutaneous and simultaneous assessment of the velocities in a number of adjacent sample volumes as a continuous function of time. A multigate pulsed Doppler system processing the information originating from presented.

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Doppler Radar System for Noncontact Bio-signal measurement (비접촉 방식의 생체 신호 측정을 위한 도플러 레이더 시스템)

  • Shin, Jae-Yeon;Cho, Sung-Pil;Jang, Byung-Jun;Park, Ho-Dong;Lee, Yun-Soo;Lee, Kyoung-Joung
    • Proceedings of the IEEK Conference
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    • pp.357-359
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    • 2009
  • In this paper, the 2.4GHz doppler radar system consisting of the doppler radar module and a baseband module were designed to detect heartbeat and respiration signal without direct skin contact. A bio-radar system emits continuous RF signal of 2.4GHz toward human chest, and then detects the reflected signal so as to investigate cardiopulmonary activities. The heartbeat and respiration signals acquired from quadrature signal of the doppler radar system are applied to the pre-processing circuit, amplification circuit, and the offset circuit of the baseband module. ECG(electrocardiogram) and reference respiration signals are measured simultaneously to evaluate the doppler radar system. As a result, the respiration signal of doppler radar signal is detected to 1m without complex digital signal processing. The sensitivity and calculated from I/Q respiration signal were $98.29{\pm}1.79%$, $97.11{\pm}2.75%$, respectively, and positive predictivity were $98.11{\pm}1.45%$, $92.21{\pm}10.92%$, respectively. The sensitivity and positive predictivity calculated from phase and magnitude of the doppler radar were $95.17{\pm}5.33%$, $94.99{\pm}5.43%$, respectively. In this paper, we confirmed that noncontact real-time heartbeat and respiration detection using the doppler radar system has the possibility and limitation.

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Audio Processing Algorithm Using Base Line Shift Method in Pulsed Doppler Systems (PW 도플러 시스템에서 Base Line 이동 기법을 이용한 오디오 신호 처리 방법)

  • 김기덕;송태경
    • Journal of Biomedical Engineering Research
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    • v.20 no.3
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    • pp.275-281
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    • 1999
  • Conventional PW Doppler systems suffer from the ambiguity of measured blood velocities due to the spectrum aliasing when the corresponding Doppler frequencies are greater than the Nyquist frequency. Base-line shift is a customary method for dealiasing the Doppler spectrums. I lowever, Doppler audio signals still remain unchanged even when the base-line shift method is applied. This paper de scribes an method for dealiasing both the Doppler spectra and audio signals by using sampling rate expansion, frequency shifting, and filtering poerations. For undirectional flows, the method can increase the maximum detectable Doppler frequency from the Nyquist limit of one-half of the Pulse Repetition Frequency(PRF) to the PRF. Experiments with real data have been performed to verify the proposed method.

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General Derivation of the Doppler Effect by Using a Space-Time Graph and Its Application (시공 그래프를 이용한 도플러 효과의 일반적 유도와 적용)

  • Kim, Gyhyuk
    • New Physics: Sae Mulli
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    • v.67 no.11
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    • pp.1342-1347
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    • 2017
  • We derived the Doppler effect from geometric analysis of a space-time graph and found the general solution of the Doppler effect for 3-dimensional plane wave and spherical wave. In our general solution, we were able to treat symmetrically the motion of the wave source and that of detector and to integrate the formulas for the elastic wave and the light. Applying the formula to a relativistic aberration, we presented a simpler explanation of related physical concepts. In the case of 3-dimensional spherical waves, we expected a new transverse Doppler effect. The geometric derivation of the Doppler effect should allow students to study the Doppler effect more consistently and systematically.

Classification of Doppler Audio Signals for Moving Target Using Hidden Markov Model in Pulse Doppler Radar (펄스 도플러 레이더에서 HMM을 이용한 이동표적의 도플러 오디오 신호 식별)

  • Sim, Jae-Hun;Lee, Jung-Ho;Bae, Keun-Sung
    • Journal of IKEEE
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    • v.22 no.3
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    • pp.624-629
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    • 2018
  • Classification of moving targets in Pulse Doppler Radar(PDR) for surveillance and reconnaissance purposes is generally carried out based on listening and training experience of Doppler audio signals by radar operator. In this paper, we proposed the automatic classification method to identify the class of moving target with Doppler audio signals using the Mel Frequency Cepstral Coefficients(MFCC) and the Hidden Markov Model(HMM) algorithm which are widely used in speech recognition and the classification performance was analyzed and verified by simulations.

Accuracy of Pulsed Doppler Ultrasound Velocity Measurements : In Vitro Flow Phantom Study (Pulsed Doppler 초음파속도측정의 정확도 판정 : 유동 phantom 연구)

  • Kim, Young-Ho;Min, Byung-Goo
    • Proceedings of the KOSOMBE Conference
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    • v.1994 no.12
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    • pp.153-156
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    • 1994
  • An in vitro steady flow experiment was performed in order to test the accuracy of velocity measurement obtained through a pulsed Doppler echocardiography. A flow phantom was designed for the use in a wide velocity range at a given flow rate. The results showed that the pulsed Doppler velocity measurement obtained in this flow phantom is accurate at low flow rates. However, ultrasound velocity measurement should be performed under a careful considerations of PRF and Doppler gain settings, especially at higher flow rates.

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Interpertation of Doppler Indicies in Neurosonologic Examinations (신경초음파 검사에서 Doppler소견의 판독)

  • Kim, Jei
    • Annals of Clinical Neurophysiology
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    • v.1 no.1
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    • pp.47-54
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    • 1999
  • The Doppler in neurosonologic examination could be applied to blood flow to determine its movement, the direction of its movement, and how fast it is. Indicies of the Doppler study denoted velocity, direction, and amount of RBC in the examined vessel. Systolic. diastolic, and mean blood flow velocities represent velocity of RBCs in a sample volume. Blood flow direction to the probe means direction of RBC to the probe. Size of amplitude displays toe amount of the RBCs passing the sample volume. Spectral broadening means presence of turbelence. The RBC movements and hemodynamics at the examined vessels can be estimated by analysis of Doppler indicies The formation and meaning of each of neurosonologic Doppler study is described in the present review.

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Stabilizing circuit of doppler beat signal obtained by coherence-dependent fiber-optic laser doppler velocimeter

  • Shinohara, shigenobu;Michiwaki, Motohiko;Ikeda, Hiroaki;Yoshida, Hirofumi;Sawaki, Toshiko;Sumi, Masao
    • 제어로봇시스템학회:학술대회논문집
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    • pp.434-439
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    • 1993
  • Described is a stabilizing circuit of the Doppler beat signal obtained by the coherence-dependent fiber-optic laser Doppler velocimeter (LDV), which employs both a self-mixing laser diode (SM-LD) and a 10m-100m long optical fiber. The stabilizing circuit maintains the SM-LD drive current at an optimum value, which gives a maximum Doppler signal during long hours.

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