serrated curve in linear f-k

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koetl
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Joined: Thu Aug 06, 2015 8:30 am

serrated curve in linear f-k

Postby koetl » Fri Apr 01, 2016 11:17 am

Hello dear admin,

my problem is that the resulting dispersion image from linear f-k toolbox of my data shows a serrated progression (see example image). After trying all offered options from the toolbox I was not able to get a smooth curve progression.

The survey design was adapted to a linear MASW survey (30m offset, 48 channels, 1 m spacing of receivers, 0.512 ms recording interval).

Since I thought to avoid a poor spectral resolution, with named recording parameters, my guess would be a missing zero padding in space.

Could this be possible? Do you have any ideas to improve the image (beside using HRFK)?

Sincerely,
Maik
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admin
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Re: serrated curve in linear f-k

Postby admin » Tue May 10, 2016 8:05 pm

Hi,

This is probably due to a rather short time window which results into a large sampling interval on the Fourier spectrum. You can choose a larger time window (second tab in toolbox) even larger then the available data. Geopsy will set all missing sample to 0 (zero-padding). It will make the spectrum denser and hence will smooth your curve. Theoretically speaking you are not adding any distortion to your results. Make sure that you are also applying a taper the data (first tab in toolbox).


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