<p>Filtering is always a convolution of the signal. What you are doing in the frequency domain will also be manifested in the time domain. A sharp edge in frequency domain will create a long convolution in time domain. </p>

<p>Ormsby (or trapezoidal) filters cause strong ringing if the slope is steep due to the <a href="https://en.wikipedia.org/wiki/Gibbs_phenomenon" rel="noreferrer">Gibbs effect</a>. To reduce the ringing, make the slopes more gentle (eg 6, 12, 45, 60) or try to taper the filter slopes. </p>

<p>However, it appears that you are using a strong <a href="http://www.xsgeo.com/course/gain.htm" rel="noreferrer">AGC</a>. Check if the ringing is actually a problem before smoothening the filter. </p>

<p>Some of the ringings will also disappear if you intend to F/K filter the direct waves. </p>

CC BY-SA 3.0
2017-06-30T01:40:25.263Z
2017-06-30T01:40:25.263Z
user2821
<p>I used the corner filter (band pass) with this frequency values (8,10,45,50). I get ringing effect on the data. my questions are:</p>

<ol>
<li>what is the name of this effect and the cause?</li>
<li>should be removed and how?
3.on what basis the frequency values should be chosen?</li>
<li>what are the visual features of seismic data make us decided the processing steps.   </li>
</ol>

<p><em>After filter:</em> </p>

<p><a href="https://i.sstatic.net/FqcRu.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/FqcRu.png" alt="data after filter "></a></p>

<p><em>Before filter:</em></p>

<p><a href="https://i.sstatic.net/O5MVe.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/O5MVe.png" alt="data before filter "></a> </p>

<geophysics><seismology>
What causes ringing effect when using corner filter?
Liath Fahad
# What causes ringing effect when using corner filter?

(Asked by: username_0 on 2017-06-23)

I used the corner filter (band pass) with this frequency values (8,10,45,50). I get ringing effect on the data. my questions are:

1. what is the name of this effect and the cause?
2. should be removed and how?
   3.on what basis the frequency values should be chosen?
3. what are the visual features of seismic data make us decided the processing steps.

*After filter:*

[![data after filter ](https://i.sstatic.net/FqcRu.png)](https://i.sstatic.net/FqcRu.png)

*Before filter:*

[![data before filter ](https://i.sstatic.net/O5MVe.png)](https://i.sstatic.net/O5MVe.png)

**Tags:** geophysics, seismology


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## 1 answers

### Answer by username_1 on 2017-06-30. Score: 5

Filtering is always a convolution of the signal. What you are doing in the frequency domain will also be manifested in the time domain. A sharp edge in frequency domain will create a long convolution in time domain.

Ormsby (or trapezoidal) filters cause strong ringing if the slope is steep due to the [Gibbs effect](https://en.wikipedia.org/wiki/Gibbs_phenomenon). To reduce the ringing, make the slopes more gentle (eg 6, 12, 45, 60) or try to taper the filter slopes.

However, it appears that you are using a strong [AGC](http://www.xsgeo.com/course/gain.htm). Check if the ringing is actually a problem before smoothening the filter.

Some of the ringings will also disappear if you intend to F/K filter the direct waves.


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