SURADON - compute forward or reverse Radon transform or remove multiples by using the parabolic Radon transform to estimate multiples and subtract. suradon stdout [Optional Parameters] Optional Parameters: choose=0 0 Forward Radon transform 1 Compute data minus multiples 2 Compute estimate of multiples 3 Compute forward and reverse transform 4 Compute inverse Radon transform igopt=1 1 parabolic transform: g(x) = offset**2 2 Foster/Mosher psuedo hyperbolic transform g(x) = sqrt(depth**2 + offset**2) 3 Linear tau-p: g(x) = offset 4 abs linear tau-p: g(x) = abs(offset) offref=2000. reference maximum offset to which maximum and minimum moveout times are associated interoff=0. intercept offset to which tau-p times are associated pmin=-200 minimum moveout in ms on reference offset pmax=400 maximum moveout in ms on reference offset dp=16 moveout increment in ms on reference offset pmula=80 moveout in ms on reference offset where multiples begin at maximum time pmulb=200 moveout in ms on reference offset where multiples begin at zero time depthref=500. Reference depth for Foster/Mosher hyperbolic transform nwin=1 number of windows to use through the mute zone f1=60. High-end frequency before taper off f2=80. High-end frequency prewhite=0.1 Prewhitening factor in percent. cdpkey=cdp name of header word for defining ensemble offkey=offset name of header word with spatial information nxmax=120 maximum number of input traces per ensemble Optimizing Parameters: The following parameters are occasionally used to avoid spatial aliasing problems on the linear tau-p transform. Not recommended for other transforms... ninterp=0 number of traces to interpolate between each input trace prior to computing transform freq1=3.0 low-end frequency in Hz for picking (good default: 3 Hz) (Known bug: freq1 cannot be zero) freq2=20.0 high-end frequency in Hz for picking (good default: 20 Hz) lagc=400 length of AGC operator for picking (good default: 400 ms) lent=5 length of time smoother in samples for picker (good default: 5 samples) lenx=1 length of space smoother in samples for picker (good default: 1 sample) xopt=1 1 = use differences for spatial derivative (works with irregular spacing) 0 = use FFT derivative for spatial derivatives (more accurate but requires regular spacing and at least 16 input tracs--will switch to differences automatically if have less than 16 input traces) Credits: CWP: John Anderson (visitor to CSM from Mobil) Spring 1993 Multiple removal notes: Usually the input data are NMO corrected CMP gathers. The first pass is to compute a parabolic Radon transform and identify the multiples in the transform domain. Then, the module is run on all the data using "choose=1" to estimate and subtract the multiples. See the May, 1993 CWP Project Review for more extensive documentation. NWIN notes: The parabolic transform runs with higher resolution if the mute zone is honored. When "nwin" is specified larger than one (say 6), then multiple windows are used through the mute zone. It is assumed in this case that the input data are sorted by the offkey header item from small offset to large offset. This causes the code to run 6 times longer. The mute time is taken from the "muts" header word. Beware, the SU mute module does not set this header word as one would normally expect. You have to manually set it yourself. References: Anderson, J. E., 1993, Parabolic and linear 2-D, tau-p transforms using the generalized radon tranform, in May 11-14, 1993 Project Review, Consortium Project on Seismic Inverse methods for Complex Structures, CWP-137, Center for Wave Phenomena internal report. Other References cited in above paper: Beylkin, G,.1987, The discrete Radon transform: IEEE Transactions of Acoustics, Speech, and Signal Processing, 35, 162-712. Chapman, C.H.,1981, Generalized Radon transforms and slant stacks: Geophysical Journal of the Royal Astronomical Society, 66, 445-453. Foster, D. J. and Mosher, C. C., 1990, Multiple supression using curvilinear Radon transforms: SEG Expanded Abstracts 1990, 1647-1650. Foster, D. J. and Mosher, C. C., 1992, Suppression of multiples using the Radon transform: Geophysics, 57, No. 3, 386-395. Gulunay, N., 1990, F-X domain least-squares Tau-P and Tau-Q: SEG Expanded Abstracts 1990, 1607-1610. Hampson, D., 1986, Inverse velocity stacking for multiple elimination: J. Can. Soc. Expl. Geophs., 22, 44-55. Hampson, D., 1987, The discrete Radon transform: a new tool for image enhancement and noise suppression: SEG Expanded Abstracts 1978, 141-143. Johnston, D.E., 1990, Which multiple suppression method should I use? SEG Expanded Abstracts 1990, 1750-1752. Trace header words accessed: ns, dt, cdpkey, offkey, muts