DocumentCode :
2768371
Title :
Invariance of Doppler bandwidth with flow axis displacement
Author :
Newhouse, V.L. ; Reid, J.M.
Author_Institution :
Drexel Univ., Philadelphia, PA, USA
fYear :
1990
fDate :
4-7 Dec 1990
Firstpage :
1533
Abstract :
It is known that if single-frequency, continuous-wave ultrasound or electromagnetic energy is reflected from straight line flow, defined here as one or more scatterers moving with constant velocity along an infinite straight line, the Doppler effect will shift the echo spectrum center frequency from the transmitted value, and broaden its bandwidth. It is shown here that if such straight line flow is shifted anywhere in the field without change of orientation, the absolute echo bandwidth remains unchanged. This result is unexpected, since the bandwidth arises from amplitude modulation of the echo from the scatterers as they pass through the incident field, and the shape of this field varies with position. The Doppler bandwidth may therefore be used to estimate the transverse component of the flow velocity anywhere in the sound beam. The effect of the system relative aperture on the minimum spectral broadening and maximum frequency indication may also be assessed at any range
Keywords :
Doppler effect; biomedical measurement; biomedical ultrasonics; flow measurement; haemodynamics; ultrasonic velocity measurement; Doppler bandwidth; absolute echo bandwidth; clinical implications; echo spectrum center frequency; flow axis displacement; flow velocity; maximum frequency indication; minimum spectral broadening; single-frequency CW EM energy; single-frequency CW US; straight line flow; Acoustic scattering; Apertures; Bandwidth; Biomedical engineering; Doppler effect; Electromagnetic scattering; Fourier transforms; Frequency estimation; Ultrasonic imaging; Ultrasonic transducers;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Ultrasonics Symposium, 1990. Proceedings., IEEE 1990
Conference_Location :
Honolulu, HI
Type :
conf
DOI :
10.1109/ULTSYM.1990.171623
Filename :
171623
Link To Document :
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