Analyzing amplitude and frequency spectrum(s) of the input data
Spectral Analysis evaluates the frequency content of seismic traces or gathers to support QC, parameter selection, and interpretation. It is commonly used to assess bandwidth, identify noise, guide filter design, and validate processing steps such as deconvolution, correlation, and enhancement.
The module computes spectra (or time–frequency attributes) over user-defined windows and displays results in normalized, decibel, or absolute amplitude scales. Optional picking and muting tools allow focused analysis of specific frequency bands or time intervals.
In case of the Fast Spectral Analysis, it allows the user to perform the spectral analysis as per the user inputs like time and trace positions.
GGather collection - add the input data gather collection by clicking on the 
icon.
Input gather - connect/reference to the input gather where the user perform the spectral analysis.
Smooth window - smooths spectrum curve. Higher values produce smoother spectrum. By default, 1
Max frequency - specify the maximum frequency should be considered. By default, 500 Hz.
Normalization mode { Normalized, Db, Amplitude } - specifies how spectral amplitudes are scaled for display and comparison. By default, Amplitude.
Normalized - scales amplitudes to a common reference value like 1 (maximum). Best for relative bandwidth comparison across traces/gathers.
Db - converts amplitudes to decibels (log scale). Best for dynamic range analysis and weak-signal visibility.
Amplitude - displays absolute linear amplitudes. Best for true energy comparison and quantitative QC.
Selected window - this section deals with user inputs. User can choose specific time and traces to analyze the spectrum response.
Time start - specify the starting time window to perform the spectral analysis. By default, -1.
Time end - specify the ending time window to perform the spectral analysis. By default, -1.
Trace start - provide the starting trace to consider in the spectral analysis. By default, -1.
Trace end - provide the ending trace number to consider in the spectral analysis. By default, -1.
Number of threads - One less than total no of nodes/threads to execute a job in multi-thread mode. Limit number of threads on main machine.
Skip - By default, FALSE(Unchecked). This option helps to bypass the module from the workflow.
There is no output data available from this module.
There is no information available for this module.
In this example workflow, we are reading a stack section as an input gather. As we know, any shot gather (common source/receiver/bin) or stack can be used to perform the spectral analysis.
Adjust the parameters as per the input data requirement. We are executing this workflow with the default parameters.
There are no action items available for this module so the user can ignore it.
YouTube video lesson, click here to open [VIDEO IN PROCESS...]
Yilmaz. O., 1987, Seismic data processing: Society of Exploration Geophysicist
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