Real and complex Doppler effects in lossy media

Author

Censor, Dan

Author_Institution

Dept. of Electr. & Comput. Eng., Ben Gurion Univ. of the Negev, Beer Sheva, Israel

Volume

39

Issue

2

fYear

1992

fDate

3/1/1992 12:00:00 AM

Firstpage

187

Lastpage

195

Abstract

The theory of the Doppler effect in the presence of lossy media and moving scatterers is investigated. Essentially two kinds of phenomena emerge, which are not distinguishable in the conventional case of lossless media. When the scatterers move uniformly, or the equation of motion involves a slowly varying velocity, it is shown that propagation in lossy media involves complex Doppler effects. The complications introduced by the received complex frequency signal are discussed. It is shown that spectrum broadening occurs, and that, in certain cases, by using judiciously chosen temporal filters, the spectral degradation of the received signal can be counteracted. The second class of phenomena is associated with periodic and harmonic motion, when the scatterer is vibrating around a fixed location. In this case the incident wave is frequency modulated by the moving scatterer, giving rise to sidebands of real frequencies.<>

Keywords

Doppler effect; acoustic signal processing; acoustic wave propagation; acoustic wave scattering; acoustical Doppler effect; complex Doppler effects; frequency modulated; harmonic motion; lossy media; moving scatterers; periodic motion; real Doppler effects; received complex frequency signal; sidebands of real frequencies; spectral degradation; spectrum broadening; temporal filters; Acoustic scattering; Attenuation; Degradation; Doppler effect; Doppler shift; Equations; Filters; Frequency; Propagation losses; Remote sensing;

fLanguage

English

Journal_Title

Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on

Publisher

ieee

ISSN

0885-3010

Type

jour

DOI

10.1109/58.139114

Filename

139114