ٍfrom seismic data processing course at USM Malaysia

1. Seismic Data Processing
Main Processing Sequence
Dr Amin Khalil
School of Physics, USM

2. Today’s Agenda
• IIR filters
And
• Main Processing Sequences

4. Properties of an IIR Filter
• The general equation of an IIR filter can be
expressed as follows:
 













M
k
k
k
N
k
k
k
M
M
N
N
za
zb
zaza
zbzbb
zH
1
0
1
1
1
10
1
1 

 ak and bk are the filter coefficients.

5. Properties of an IIR Filter
• The transfer function can be factorised to
give:
      
    
 
 zX
zY
pzpzpz
zzzzzz
kzH
N
N






21
21
 Where: z1, z2, …, zN are the zeros,
p1, p2, …, pN are the poles.

6. Properties of an IIR Filter
• The transfer function can be factorised to
give:
      
    
 
 zX
zY
pzpzpz
zzzzzz
kzH
N
N






21
21
 For the implementation of the above
equation we need the difference equation:
     
   






M
k
k
N
k
k
k
knyaknxb
knxkhny
10
0

7. Advantage
Use less memory than FIR filters
Disadvantages
•They are more susceptable to problems of finite-length arithmetic, such as
noise generated by calculations, and limit cycles. (This is a direct
consequence of feedback: when the output isn't computed perfectly and is
fed back, the imperfection can compound.)
•They are harder (slower) to implement using fixed-point arithmetic.
•They don't offer the computational advantages of FIR filters for multirate
(decimation and interpolation) applications.

8. Types of filters
Matching question.

10. Basic Processing Sequence:

13. Sorting of seismic data
This step describe the way we collect and view or
seismic data. It consists of the following:

15. CMP gather

17. Common shot vs CMP gather

18. Zero-Offset gather.
This type is applied such that both shots and receivers are at the
same location.

20. Reference for this
lecture:
Drijkoningen, G. G. and Verschuur, D.J., 2003. Seismic data processing. TU Delft.
http://geodus1.ta.tudelft.nl/PrivatePages/G.G.Drijkoningen/Lectur
eNotes/SeismicProcessing%28tg001_ta3600%29.pdf
Link

21. End
Thank you