The Effect of Harmonic Distortion in the Use of Vibratory Surface Sources

Seriff, A. J.; Kim, W. H.

doi:10.1190/1.1440087

Cited by 58 publications

(35 citation statements)

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“…Before introducing the decomposition of ground force, we first analyze the fundamental signal and harmonics based on the theory proposed by Seriff and Kim (1970). Let us take an up-sweep for example.…”

Section: Analysis Of the Ground Force Signalmentioning

confidence: 99%

An effective method for reducing harmonic distortion in correlated vibroseis data

Zhou

Chen

et al. 2015

Journal of Applied Geophysics

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Section: Analysis Of the Ground Force Signalmentioning

confidence: 99%

An effective method for reducing harmonic distortion in correlated vibroseis data

Zhou

Chen

et al. 2015

Journal of Applied Geophysics

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“…Seriff and Kim (1970) described this distortion phenomenon in detail. Several methods to eliminate harmonic distortions have been investigated over the last 40 years, many of them with limited success, since they are often difficult to implement and control with respect to quality and performance.…”

Section: Introductionmentioning

confidence: 97%

Effective elimination of subharmonic ghost events from vibroseis data

Stiller

Jaeckel

Weber

2012

Geophysical Prospecting

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Harmonic or subharmonic noise is often present in vibroseis data as reverberation‐like, laterally coherent bands occurring parallel to and before or after, the main events. Such periodic noise is typically generated during the standard correlation process when the actual source signal travelling through the subsurface is, for whatever reason, different from the desired source signal, i.e., the pilot‐sweep controlling the baseplate and used for correlation. A typical cause can be that harmonic or subharmonic frequency partials are generated in addition to the vibroseis sweep's desired fundamental frequencies. These harmonics produce strong ‘ghost events’ during correlation of the geophone trace with the pilot‐sweep, originating from additional correlations between the fundamental and harmonic frequencies. Especially subharmonic ‘ghosts’ will overlap with ‘good’ fundamental signals, since for typically used up‐sweeps they are folded to later traveltimes, where the signal/noise‐ratio is already lower, thus aggravating or preventing a reliable interpretation of possible later reflections. Here, a method is introduced to remove these unwanted noise trains (with only negligible impact on the fundamental signal) by transforming the seismogram traces into a so‐called ‘(sub)harmonic domain’. In this domain, the respective harmonic noise portions are focused and separated from the fundamental signals, enabling easier detection and appropriate suppression. After back‐transformation to the x‐T domain, the records are free from the corresponding harmonic contamination and can then be processed as usual. The method operates in a data‐driven fashion, i.e., the traces are not uniformly processed but are processed depending upon their actual (sub)harmonic content. The decontamination procedure can be applied universally, i.e., to uncorrelated/correlated and/or vertically unstacked/stacked data either in a manual, semiautomated or fully automated manner. The method works perfectly for synthetic vibroseis traces with or without harmonic/subharmonic portions. The application to real, crustal‐scale vibroseis records that were acquired in 2006 in the Dead Sea region, Israel and that were severely contaminated by subharmonic ground‐roll ghosts covering reflectivity from the basement to the Moho, shows the robustness and success of the presented method.

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“…Previously, many methods have been proposed for suppressing harmonic interference. In a fundamental study, Seriff and Kim (1970) found that harmonic distortion will create either a correlation-ghost forerunner or a tail at both positive and negative correlation times if the harmonically distorted sweep is used as the correlation operator. They suggested using pilot signals to perform correlation.…”

Section: Introductionmentioning

confidence: 99%