Results 251 to 260 of about 63,794 (294)
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Doppler Effect in Positive Rays of Hydrogen
Nature, 1944THE Balmer lines in the spectra of the positive rays of hydrogen show Doppler displacement dλ given by the relation where λ is the wave-length of the light emitted by a neutral atom of the positive ray beam, moving with a velocity ν, the direction of motion of the atom making an angle θ with the direction of observation; c is the velocity of light.
B. DASANNACHARYA, G. K. DAS
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Doppler-Aided Algorithm for BeiDou Position
2013Real-time GNSS positioning rely mainly on pseudorange and carrier-phase. The pseudorange is not accurate because of a lot of noise and interference in environment. High-precision carrier-phase used to smooth pseudorange. While, when cycle slip occurs, the carrier-phase measurement is bias.
Dengyun Lei, Weijun Lu, DunShan Yu
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Doppler-aided position estimation for HS-GNSS
2019 53rd Asilomar Conference on Signals, Systems, and Computers, 2019During the last decade, because of the growing needs for indoor navigation, many authors tends to improve the processing gain of the GNSS receivers by increasing the observation time. In this paper, we show that this gain can also be improved by considering the Doppler information during the trilateration step.
François Vincent +2 more
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Doppler Echocardiographic Evaluation of Prosthetic Valves in Tricuspid Position
Asian Cardiovascular and Thoracic Annals, 2003Doppler echocardiographic characteristics of 29 normally functioning prosthetic valves (23 mechanical, 6 biological) and 8 obstructed mechanical prostheses in the tricuspid position are reported. In normally functioning prostheses, peak velocity, mean pressure gradient, and pressure-half time were 1.25 ± 0.18 m·sec−1, 2.6 ± 1.1 mm Hg, and 122.6 ± 30.7
Shigeaki, Aoyagi +4 more
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Statistical techniques and Doppler satellite positioning
Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1980Two problems are addressed: ( a ) the detection of outliers in (Doppler satellite) observations, and ( b ) the testing of coordinates in (Doppler satellite) networks. In both problems, confidence regions of the ‘out of context’ and ‘within context’ varieties are developed, and it is shown ...
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Improved accuracy from Doppler satellite positioning
Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1980The Defense Mapping Agency has initiated a broad study to investigate the possibility of improving the accuracy and precision of Doppler satellite geodetic positioning. The investigations include point positioning and short arc network techniques with the use of both broadcast and precise ephemerides.
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Doppler radar sensor positioning in a fall detection system
2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2012Falling is a common health problem for more than a third of the United States population over 65. We are currently developing a Doppler radar based fall detection system that already has showed promising results. In this paper, we study the sensor positioning in the environment with respect to the subject.
Liang, Liu +4 more
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An Anti-spoofing Method Based on Doppler Positioning
The International Technical Meeting of the The Institute of Navigation, 2017The vulnerability of GNSS to spoofing attacks has received much attention in recent years. Among various spoofing techniques, replay attack is a typical and common one due to its simplicity and effectiveness. To detect and mitigate spoofing threats including the replay spoofing, a new anti-spoofing method is proposed.
Fengkui Chu +4 more
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Receiver Design for Doppler Positioning with Leo Satellites
ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2019A framework for positioning with low Earth orbit (LEO) satellite signals is proposed. The framework employs an extend Kalman filter (EKF) to estimate a receiver’s position using Doppler frequency measurements from LEO satellites. The satellites’ positions and velocities are known through two-line element (TLE) files.
Joe J. Khalife, Zaher M. Kassas
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Research on A-GPS Rapid Positioning Algorithm Based on Doppler Positioning
2014The time to first fix (TTFF) of conventional GPS receiver need one minute or more in the case of autonomous cold start, when in weak signal environments like indoors or urban canyons, even tens of minutes are difficult to achieve the TTFF. Assisted Global Positioning System provided ephemeris, a priori time and a priori position for a A-GPS receiver ...
Zhiyong Huang +3 more
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