Results 211 to 220 of about 18,290 (263)
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Initial Satellite Access Authentication Based on Doppler Frequency Shift
IEEE Wireless Communications Letters, 2021The future mobile system shall be able to support satellite access to provide an ubiquitous wireless connection service. Satellite communication is vulnerable to spoofing attacks due to the open nature of wireless channels, especially for the downlink satellite system information signalling (SIS) which has not been authenticated yet before initial ...
Qing-Yi Fu +3 more
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CANCELLATION OF DOPPLER FREQUENCY SHIFT
1963Abstract : A circuit is described which is capable of canceling first-order Doppler frequency shifts. It has potentialities in the fields of communication, data transmission, and navigation systems for vehicles moving at high velocities. The circuit has the following features: (1) Received and transmitted frequencies at each of the stations involved ...
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Doppler frequency shift in a refractive atmosphere
Journal of Aircraft, 1987A general derivation is given for the Doppler-shifted received frequency due to source and receiver motion of uniform velocity in a steady-state, refractive medium with spatial gradients in velocity and temperature. The results from three cases of this generalized equation are especially important.
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Frequency Detuning Control by Doppler Shift
2011In this work, a control strategy for ship parametric roll resonance is developed by changing the frequency of the parametric excitation. This is achieved by varying the ship’s forward speed. This changes the perceived frequency of the waves, known as the encounter frequency (and thus the frequency of parametric excitation), via Doppler shift.
Christian Holden +2 more
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Doppler frequency shift of sound apparatus
The Physics Teacher, 2011A large 1-m diameter rotary table with a semicircular waveguide along its periphery is the basis of the Doppler frequency shift of sound apparatus. A “button” speaker is attached to the outer edge of the rotary table and a microphone pickup is positioned on the wall of the waveguide at its midpoint.
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Quantitative measurement of the Doppler shift at an ultrasonic frequency
American Journal of Physics, 1976Two ultrasonic transducers, the receiver stationary at the end on a linear air track, and the source mounted on a moving glider, are the basis for a Doppler shift experiment. The source frequency and the shifted receiver frequency are fed into a digital phase detector circuit which produces an output difference frequency with a sinusoidal waveform ...
R. C. Nerbun, R. A. Leskovec
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Blind Source Separation in the Presence of Doppler Frequency Shifts
Proceedings. (ICASSP '05). IEEE International Conference on Acoustics, Speech, and Signal Processing, 2005., 2006We address the problem of blind separation of sources, mixed subject to possible Doppler frequency-shifts, differing between sources and between sensors. This situation is likely to occur, e.g. in scenarios involving mobile sensors and/or sources, but so far the multiple sources case does not seem to have been addressed (at least not in open literature,
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Doppler Shift Frequency to Voltage Conversion Techniques
1975Three methods of converting the Doppler signal to voltage proportional to mean velocity are compared. The traditional zero crosser is simple and reliable, however, erroneous readings are obtained in the presence of noise and broad band Doppler signals.
F. D. McLeod, R. Daigle, C. W. Miller
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Laser Doppler velocimeter with optical frequency shifting
Optics & Laser Technology, 1973Abstract A bi-directional laser Doppler velocimeter utilizing optical frequency shifting has been developed. Optical frequency shifting is achieved by using a rotating radial grating. A high diffraction efficiency permits the system to be used in the fringe mode.
Oldengarm, J. +2 more
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Data-Aided Doppler Frequency Shift Estimation and Compensation for UAVs
IEEE Internet of Things Journal, 2020With the surge of Internet of Things (IoT) applications using unmanned aerial vehicles (UAVs), there is a huge demand for the mobile broadband service with gigabyte per second data rate in the UAV-aided fifth generation (5G) IoT system. However, Doppler frequency shift (DFS) deteriorates the link performance of UAV-aided 5G system in the highly dynamic
Qixun Zhang +4 more
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