Step 3. Run an f/k filter on a single file to determine which slopes mitigate the effects of noise and ground roll on the reflection data. Use the perl script Sudipfilt_class.pl. By examining the data it was observed that significant noise slopes in the negative direction whereas the data has a positive slope. By applying an f/k filter to all the negative slopes, noise was reduced significantly. To cancel out the effects of ground roll on the data I calculated the slope of the ground roll and set parameters that would encompass the calculated slopes. F/k is frequency divided by wavenumber which is equal to frequeny times wavelength which is equal to velocity. Because of this relationship, the slopes can be measure directly from an image. The parameters used to cancel out the ground roll are: slopes=10,15,60,70. To cancel the negative sloping noise I eliminated all negative sloping data: slopes=-100,-90,-1,0. A. B. C. D. E. F. Figure 4. A, B, and C are images of file 1001.g.su before the f/k filter was performed. D,E, and F are images of file 1001.g.su after the f/k filter was performed. Band pass filter vs. F/K filter By experimenting with different band pass and f/k filters I determined that the f/k filtering did a decent job at canceling the ground roll in the data, but the band pass filter seemed to do a better job. Therefore I used a hybrid filtering technique and used a band pass filter to cancel the ground roll and ran an f/k filter to cancel negative sloping noise. Figure 5 – Resulting image after band pass and f/k filtering.
Step 3. Run an f/k filter on a single file to determine which slopes mitigate the effects of noise and ground roll on the reflection data. Use the perl script Sudipfilt_class.pl. By examining the data it was observed that significant noise slopes in the negative direction whereas the data has a positive slope. By applying an f/k filter to all the negative slopes, noise was reduced significantly. To cancel out the effects of ground roll on the data I calculated the slope of the ground roll and set parameters that would encompass the calculated slopes. F/k is frequency divided by wavenumber which is equal to frequeny times wavelength which is equal to velocity. Because of this relationship, the slopes can be measure directly from an image. The parameters used to cancel out the ground roll are: slopes=10,15,60,70. To cancel the negative sloping noise I eliminated all negative sloping data: slopes=-100,-90,-1,0. A. B. C. D. E. F. Figure 4. A, B, and C are images of file 1001.g.su before the f/k filter was performed. D,E, and F are images of file 1001.g.su after the f/k filter was performed. Band pass filter vs. F/K filter By experimenting with different band pass and f/k filters I determined that the f/k filtering did a decent job at canceling the ground roll in the data, but the band pass filter seemed to do a better job. Therefore I used a hybrid filtering technique and used a band pass filter to cancel the ground roll and ran an f/k filter to cancel negative sloping noise. Figure 5 – Resulting image after band pass and f/k filtering.
W.Torsch_Final%20Project.docx