Results 21 to 30 of about 118,769 (293)

Solid breast neoplasms: Differential diagnosis with pulsed Doppler ultrasound [PDF]

, 1994
In this prospective study, duplex Doppler ultrasound was used in 95 consecutive patients with solid breast masses to evaluate the presence of neovascular flow.
Kruyt, Ph.M. (Philip), Kuijpers, T.J.A. (T. J A), Obdeijn, A.I.M. (Inge-Marie), Oudkerk, M. (Matthijs)   +3 more
core   +7 more sources

Evaluating the effectiveness of Doppler frequency shift determination using pilots in broadband transmission [PDF]

International Journal of Electronics and Telecommunications
In underwater communications, reciprocal motion between transmitter and receiver has a significant impact on reception quality. In orthogonal broadband systems that provide high bit rates, this problem becomes more important, especially in the higher ...
Agnieszka Czapiewska, Andrzej Łuksza, Ryszard Studański, Łukasz Wojewódka, Andrzej Żak   +4 more
doaj   +1 more source

Time-Frequency Integrals and the Stationary Phase Method in Problems of Waves Propagation from Moving Sources [PDF]

, 2012
The time-frequency integrals and the two-dimensional stationary phase method are applied to study the electromagnetic waves radiated by moving modulated sources in dispersive media. We show that such unified approach leads to explicit expressions for the
Burlak, Gennadiy, Rabinovich, Vladimir
core   +3 more sources

Hearing Characteristics and Doppler Shift Compensation in South Indian CF-FM Bats [PDF]

, 1980
1. Echolocation pulses, Doppler shift compensation behaviour under laboratory conditions and frequency response characteristics of hearing were recorded inRhinolophus rouxi, Hipposideros speoris andHipposideros bicolor. 2.
A. Brosset, A. Brosset, A.D. Grinnell, G. Neuweiler, G. Pollak, G. Schuller, G. Schuller, G. Schuller, Gerd Schuller, H.-U. Schnitzler, H.-U. Schnitzler, J.A. Simmons, N. Suga, Y. Gustafson   +13 more
core   +1 more source

Cell ID and Timing Estimation Techniques for Underwater Acoustic Cellular Systems in High-Doppler Environments

Sensors, 2020
In an underwater acoustic cellular (UAC) system, underwater equipment or sensor nodes need to detect the identity of an underwater base station (UBS) and synchronise it with a serving UBS. It is known that, in an underwater acoustic channel, the temporal
Muhammad Asim, Mohammed Saquib Khan, Tae Ho Im, Yong Soo Cho   +3 more
doaj   +1 more source

Robust Underwater Acoustic Communication Using the Overlapped Chirp Spread Carrier Technique in Doubly Spread Environments

IEEE Access, 2023
The performance of underwater acoustic communication is significantly affected by multipath propagation and Doppler spread. In this paper, we propose a new communication technique called overlapped chirp spread carrier (OCSC) by modifying the existing ...
Chang-Hyun Youn, Hyung-In Ra, Kyung-Won Lee, Ki-Man Kim   +3 more
doaj   +1 more source

Research of Mobile Underwater Acoustic Communication of M-Ary Combining FDM and Piecewise-LFM

Xibei Gongye Daxue Xuebao, 2019
Aiming at the countering doppler shift, a mobile underwater acoustic communication scheme of M-ary via FDM-PLFM is proposed. The cross-correlation between piecewise linear frequency modulation(PLFM) and traditional LFM signal is analyzed based on the ...

doaj   +1 more source

The Doppler effect induced by earthquakes: A case study of the Wenchuan MS8.0 earthquake

Geodesy and Geodynamics, 2022
Seismologists have found that the first arrival frequencies of P waves at different seismic stations have different widths, that is, different periods or frequencies, and they think that this phenomenon can be used to identify whether a Doppler effect is
Qicheng Li, Jingwen Sun, Guimei Xi, Jing Liu   +3 more
doaj   +1 more source

Doppler Stretch and Delay Statistical Performance Comparison for Wideband and Narrowband Signal Model

Известия высших учебных заведений России: Радиоэлектроника, 2018
Narrowband approximation of Doppler effect by a frequency shift is inappropriate for some problems of radiolocation, hydro acoustics or passive location.
I. V. Gogolev
doaj   +1 more source

Electromagnetic Doppler effect in non-reciprocal medium

AIP Advances, 2023
Reflected light from a moving object, such as a mirror, is frequency-shifted via the Doppler effect. This well-known phenomenon is used to determine the speed and direction of an object due to the red or blue shifting of the received electromagnetic ...
Douglas M. Baney
doaj   +1 more source