Description

Apply tapers smoothly fades the amplitude of each trace in and out near the start and/or end of the gather, using a Hamming-shaped window rather than an abrupt cut. It is typically used to suppress edge effects - for example, ringing or artifacts introduced by later filtering, frequency-domain transforms, or migration - by softening the very beginning and/or end of every trace before that processing step. The module works on gathers in the time, depth, or frequency domain, and automatically matches the taper length units to the domain of the incoming data.

Input data

Input gather

The seismic gather whose traces will have a taper applied at the top and/or bottom edge.

Parameters

Apply tapers on

Chooses which edge(s) of each trace receive a taper. "Top and Bottom" fades in at the start of the trace and fades out at the end; "Top" only tapers the beginning (early/shallow samples); "Bottom" only tapers the end (late/deep samples). The Taper window top and/or Taper window bottom fields below become active depending on this choice.

Default: "Top and Bottom".

Taper window top

Length of the smooth fade-in applied at the start of each trace. A Hamming-shaped ramp is applied over this length so amplitudes build up gradually instead of starting abruptly. This field is only active when "Apply tapers on" is set to "Top" or "Top and Bottom". Increase the value for a longer, gentler fade-in (useful ahead of frequency-domain processing to reduce edge artifacts); decrease it to preserve more of the early samples at full amplitude.

Default: 100 ms (0.1 s).

Taper window bottom

Length of the smooth fade-out applied at the end of each trace, working the same way as Taper window top but at the trace's bottom edge. This field is only active when "Apply tapers on" is set to "Bottom" or "Top and Bottom".

Default: 100 ms (0.1 s).

Gather domain

Shows whether the gather being processed is in the Time, Depth, or Frequency domain. This value is detected automatically from the incoming gather so the taper window lengths are interpreted with the correct vertical axis; it is not intended to be changed manually.

Default: Time domain.

Output data

Output gather

The gather after the top and/or bottom taper has been applied to every trace.

Difference gather

The difference between the input and output gathers, showing exactly what energy was attenuated by the taper near the trace edges. Use it to quality-check that the taper is not removing more of the signal than intended.

References

Harris, F. J., 1978, On the use of windows for harmonic analysis with the discrete Fourier transform: Proceedings of the IEEE, 66, 51-83.