• Title/Summary/Keyword: Doppler effect

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The Analysis and Implementation of Realistic Sound using Doppler Effect (도플러 효과를 이용한 실감 음향 분석 및 구현)

  • Yim, Yong-Min;Lim, Heung-Jun;Heo, Jun-Seok;Park, Jun-Young;Do, Yun-Hyung;Lee, Kangwhan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2017.05a
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    • pp.523-526
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    • 2017
  • In modern recently technology, 3D-Audio is used to enhance immersion in Virtual Reality. This includes interest of people about VR and AR, which related to the field of computer graphics. In fact, a lot of research has been carried out in recent years into a 3D sound field. However, the existing 3D generator device used for virtual reality does not contain Doppler effect occurred by the sound comes to or leave from a listener, while an angle from the listener and the altitude of the source sound are applied. Therefore, this paper present 3D real sound utilizing Doppler effect with spatial-rotation-speaker. We map the source sound in 3D-space into a real space where a user stays and present 3D real sound by manipulating with rotation angle, phase difference, sound output volume of the sound in 3D-space, according to the location of a virtual source sound. Utilizing both natural Doppler effect of rotating sound that is occurring by spatial-rotation-speaker and artificial Doppler effect generated by frequency-modulation of sound quality could improving the virtual reality for sound condition for perspective listening.

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Simulation Models for Investigation of Multiuser Scheduling in MIMO Broadcast Channels

  • Lee, Seung-Hwan;Thompson, John S.
    • ETRI Journal
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    • v.30 no.6
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    • pp.765-773
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    • 2008
  • Spatial correlation is a result of insufficient antenna spacing among multiple antenna elements, while temporal correlation is caused by Doppler spread. This paper compares the effect of spatial and temporal correlation in order to investigate the performance of multiuser scheduling algorithms in multiple-input multiple-output (MIMO) broadcast channels. This comparison includes the effect on the ergodic capacity, on fairness among users, and on the sum-rate capacity of a multiuser scheduling algorithm utilizing statistical channel state information in spatio-temporally correlated MIMO broadcast channels. Numerical results demonstrate that temporal correlation is more meaningful than spatial correlation in view of the multiuser scheduling algorithm in MIMO broadcast channels. Indeed, the multiuser scheduling algorithm can reduce the effect of the Doppler spread if it exploits the information of temporal correlation appropriately. However, the effect of spatial correlation can be minimized if the antenna spacing is sufficient in rich scattering MIMO channels regardless of the multiuser scheduling algorithm used.

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A Study of Frequency variable Ultrasonic Transducer for the Variation of Echo Characteristics in Reflecte Wave (반사파의 주파수 성분변화에 대응한 주파수 가변 초음파 트랜스듀서)

  • 김무준
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1997.06a
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    • pp.40-43
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    • 1997
  • It is known tat the echoes from the most objects differ from the incident pulses in amplitude and frequency .Especially, the frequency in echoes from moving target is shiftby the Doppler effect. it causes to reduce the receiving sensitivity of piezoelectric transducers that have definite band width. The electric impedance, whichis connected to the electrical terminals, notably changes the resonant frequency of a thickeness mode piezoelectric vibrator with high electromechanical doupling due to the electroelastic effect. Using this effect, we have developed a frequency controllable ultrasonic transducer which is mad eof multi-layered PZT disks to adjust to frequency shifted by Doppler effect. The characteristics of transducer can be obtained by using the equivalent circuit of transmission line model. It was confirmed experimentally that the center frequency and band width of the trasducer could be controlled by the conditions of the electrical terminals. These results coincided with theoretical results.

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Analytical Solutions of Birefringence and Dichroism Spectroscopy for the Jg = 0 → Je = 1 Transition

  • Noh, Heung-Ryoul
    • Journal of the Optical Society of Korea
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    • v.18 no.4
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    • pp.365-369
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    • 2014
  • We present accurate analytical solutions of the lineshapes of birefringence (rotation) and dichroism (absorption) spectroscopy for a circular anisotropic medium composed of atoms of the transition $J_g=0{\rightarrow}J_e=1$. The susceptibility of a weak probe beam was analytically calculated and was averaged over a Maxwell-Boltzmann velocity distribution. The lineshapes of the two spectroscopies were then presented in analytical forms at arbitrary values of the linewidths of the inhomogeneous (Doppler) broadening and the homogeneous (natural) broadening of the atoms.

The Cycle-Slip Correction of Kinematic Data using Doppler frequency (Doppler frequency를 이용한 Kinematic 자료의 Cycle-Slip 보정)

  • 손홍규;김중경;신대호
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2003.04a
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    • pp.105-109
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    • 2003
  • The occurrence of cycle slips is a major limiting factor to attain high precision positioning and navigation results with GPS. Cycle slips must be correctly repaired at the data processing stage. In this study, the technique to find cycle slips in the processing of data collected with Trimble 4700 GPS receivers is suggested. The use of Kalman filtering techniques is used in an attempt to reduce the effect of the noise in the different quantities involved and to improve the accuracy in cycle slip correction.

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Measurement of Cloud Velocity and Altitude Using Lidar's Range Detection and Digital Image Correlation

  • Park, Nak-Gyu;Baik, Sung-Hoon;Park, Seung-Kyu;Kim, Dong-Lyul;Kim, Duk-Hyeon;Choi, In-Young
    • Journal of the Optical Society of Korea
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    • v.18 no.5
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    • pp.605-610
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    • 2014
  • Clouds play an important role in climate change, in the prediction of local weather, and also in aviation safety when instrument assisted flying is unavailable. Presently, various ground-based instruments used for the measurements of the cloud base height or velocity. Lidar techniques are powerful and have many applications in climate studies, including the clouds' temperature measurement, the aerosol particle properties, etc. Otherwise, it is very circumscribed in cloud velocity measurements because there is no Doppler effect if the clouds move in the perpendicular direction to the laser beam path of Doppler lidar. In this paper, we present a method for the measurement of cloud velocity using lidar's range detection and DIC (Digital Image Correlation) system to overcome the disadvantage of Doppler lidar. The lidar system acquires the distance to the cloud, and the cloud images are tracked using the developed fast correlation algorithm of DIC. We acquired the velocities of clouds using the calculated distance and DIC algorithm. The measurement values had a linear distribution.

A Novel Detection Scheme for Reducing the Effect of Residual Doppler Frequency Offset in Spread Spectrum Systems (나머지 도플러 주파수 오프셋이 있는 대역확산 시스템에서 새로운 검파기법)

  • Yoo Seung-Soo;Kim Sun-Yong;Song Iick-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.6A
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    • pp.586-592
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    • 2006
  • In this paper, a novel detection method called the joint multiple frequency cell (JMFC) detection is addressed for spread spectrum code acquisition in the presence of residual Doppler frequency offset (RDFO). When the RDFO exists, the correlation peak used for detection during the acquisition process is split into several lower neighboring peaks, resulting in severe degradation in the detection performance, and consequently, in the overall acquisition performance. In the JMFC detection, a decision variable for detection is formed by combining several consecutive correlator outputs, so that the reduction in the correlation value due to the RDFO can be alleviated. Numerical results show that the proposed scheme can offer better detection performance over the conventional scheme based on the cell-by-cell detection.

Channel Transfer Function Estimation based on Delay and Doppler Profile for Underwater Acoustic OFDM Communication System

  • Shiho, Oshiro;Tomohisa, Wada
    • International Journal of Computer Science & Network Security
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    • v.23 no.1
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    • pp.96-102
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    • 2023
  • In this paper, we proposed Channel Transfer Function estimation based on Delay and Doppler Profile for underwater acoustic OFDM communication system. It improved the estimation accuracy of the channel transfer function by linear time interpolation the change of Scattered Pilot (SP) insertion frequency in the time direction and the time by Delay and Doppler profile that analyzes the multipath situation of the channel investigated the performance of interpolation by simulation and report it. Previous works is inserted SP every 4 OFDM. It was effective under the environment without multipath, but it has observed that the effect of CTF compensation has been lowered in multipath channel condition. In addition to be better when inserted SP every 2 OFDM. But the amount of sending data will be decrease. Therefore, we conducted research to improve 4 OFDM with new interpolator. A computer simulation was performed as a comparison of SP inserted every 4 OFDM, SP inserted every 2 OFDM, and 4 OFDM with new interpolator. the performance of the proposed system is overwhelmingly improved, and the performance is slightly improved even 64 QAM.

EXTENDED KALMAN FILTERING OF SATELLITE DOPPLER TRACKING DATA AND IT'S APPLICATION TO ORBIT DETERMINATION PROBLEMS (확장칼만필터를 이용한 인공위성 도플러 추적자료의 처리와 궤도 결정)

  • 김동규;최규홍
    • Journal of Astronomy and Space Sciences
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    • v.12 no.1
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    • pp.143-156
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    • 1995
  • Using a directional antenna, the Doppler effect of satellites can be detected and the orbital elements can be obtained by the Extended Kalman Filter with the observed frequency shift data. We obtained the orbital elements of NOAA-11 by the application of the Extended Kalman Filter type algorithm to the Doppler shift data of NOAA-11d and discussed the accuracy and the credibility of this algorithm.

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The Effect of Second Order Refraction on Optical Bubble Sizing in Multiphase Flows

  • Qiu, Huihe;Hsu, Chin-Tsau;Liu, Wei
    • Journal of Mechanical Science and Technology
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    • v.15 no.12
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    • pp.1801-1807
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    • 2001
  • In multiphase flne the bubble size and velocity. To achieve this, one of approaches is to utilize laser phase-Doppler anemometry. However, it was found that the second order refraction has great impact on PDA sizing method when the relative refractive index of media is less than one. In this paper, the problem of second order refraction is investigated and a model of phase-size correlation to eliminate the measurement errors is introduced for bubble sizing. As a result, the model relates the assumption of single scattering mechanism in conventional phase-Doppler anemometry. The results of simulations based on this new model by using Generalized Lorenz Mie Theory (GLMT) are compared with those based on the conventional method. An optimization method for accurately sizing air-bubble in water has been suggested.

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