... | ... | @@ -2,12 +2,8 @@ Programm src/green/disan/phadi.f |
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Navigation: [/](/) [src/](src) [green/](src_green) [disan/](src_green_disan)
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Navigation: [[Mainpage], [wiki:trunk], [wiki:branches], [wiki:tags], [wiki:vendor], [wiki:export], [wiki:admin], [wiki:docs|WikiStart]]
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**Calculate dispersion relation from phase differences**
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## Phase-slowness analysis
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Phase-slowness analysis
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-----------------------
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The theory behind this program is described by
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[[Forbriger (2003. Inversion of shallow-seismic wavefields: I. Wavefield transformation. Geophys. J. Int., 153, 719-734, appendix A)|http://dx.doi.org/10.1046/j.1365-246X.2003.01929.x]]:
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... | ... | @@ -66,6 +62,14 @@ the fit. |
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The gradient *p(ω)* is the sought phase-slowness at angular frequency
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ω.
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## Practical considerations
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1. If the wave does not consist of a single mode, *T(ω,r,,l,,)'' as a function of ''r* will not appear like a straight line. The outcome of the analysis then is undefined.
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1. If receiver distances *r,,l,,-r,,l-1,,'' are too large, signals are aliased. The actual phase difference of the Fourier signals between ''r,,l,,'' and ''r,,l-1,,'' then is larger than 2''π''. The algorithm will then not be able to obtain the correct phase slowness. Presenting phase slowness ''p(ω)'' as a function of ''ω* it will have discontinuities. |
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Practical considerations
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------------------------
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1. If the wave does not consist of a single mode, T(ω,r_l) as a
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function of r will not appear like a straight line. The outcome of the
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analysis then is undefined.
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1. If receiver distances r_l-r_(l-1) are too large, signals are
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aliased. The actual phase difference of the Fourier signals between
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r_l and r_(l-1) then is larger than 2π. The algorithm
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will then not be able to obtain the correct phase slowness. Presenting
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phase slowness p(ω) as a function of ω it will have
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discontinuities. |