SUVEL2DF - compute stacking VELocity semblance for a single time in
over Vnmo and eta in 2-D
suvel2df stdout [optional parameters]
Required Parameters:
tn zero-offset time of reflection
offsetm Maximum offset considerd
Optional Parameters:
nv=50 number of velocities
dv=50.0 velocity sampling interval
fv=1500.0 first velocity
nvh=50 number of horizotal velocities
dvh=50.0 horizontal velocity sampling interval
fvh=1500.0 first horizontal velocity
xod=1.5 maximum offset-to-depth ratio to resolve
dtratio=5 ratio of output to input time sampling intervals
nsmooth=dtratio*2+1 length of semblance num and den smoothing window
verbose=0 =1 for diagnostic print on stderr
vavg=fv+0.5*(nv-1)*dv average velocity used in the search
Notes:
Semblance is defined by the following quotient:
n-1
[ sum q(t,j) ]^2
j=0
s(t) = ------------------
n-1
n sum [q(t,j)]^2
j=0
where n is the number of non-zero samples after muting.
Smoothing (nsmooth) is applied separately to the numerator and denominator
before computing this semblance quotient.
Input traces should be sorted by cdp - suvel2df outputs a group of
semblance traces every time cdp changes. Therefore, the output will
be useful only if cdp gathers are input.
Credits:
CWP: Tariq Alkhalifah, February 1997
Trace header fields accessed: ns, dt, delrt, offset, cdp.
Trace header fields modified: ns, dt, offset.