void makeds (int ns, float *ts, float *as, int lds, int ifds, float *ds)
/*****************************************************************************
make shaping filter to correct DMO horizontal reflection response
******************************************************************************
Input:
ns number of shifts
ts array[ns] of time shifts (normalized by sampling interval)
as array[ns] of amplitudes corresponding to time shifts
lds length of shaping filter
ifds index of first sample of shaping filter (see notes)
Output:
ds array[lds] containing shaping filter
******************************************************************************
Notes:
Reasonable values for lds and ifds are lds=125 and ifds=-100.
The maximum permissible lds is the dimension of dd, di, and work below.
This function must be kept consistent with that used to perform DMO.
******************************************************************************
Author: Dave Hale, Colorado School of Mines, 11/04/90
*****************************************************************************/
#define LDMAX 400
#define LDSMAX 300
{
int ld=LDMAX,ifd=1-ld,i,is;
float one=1.0,d[LDMAX],dd[LDSMAX],di[LDSMAX],work[LDSMAX];
/* compute dmo horizontal reflection response d(t) */
for (i=0; i<ld; ++i)
d[i] = 0.0;
d[ld-1] = as[0];
for (is=1; is<ns; ++is) {
i = (int)ts[is];
d[ld-i-1] += 2.0*as[is];
}
/* compute autocorrelation of d(t) */
xcor(ld,ifd,d,ld,ifd,d,lds,0,dd);
/* compute crosscorrelation of d(t) and desired impulse i(t) */
xcor(ld,ifd,d,1,0,&one,lds,ifds,di);
/* solve symmetric toeplitz system of equations for filter */
stoepf(lds,dd,di,ds,work);
}
main(int argc, char **argv)
{
int nt; /* number of points on trace */
float dt; /* time sample interval (sec) */
float *wiener; /* Wiener error filter coefficients */
float pnoise; /* pef additive noise level */
float minlag; /* start of error filter (sec) */
int iminlag; /* ... in samples */
float maxlag; /* end of error filter (sec) */
int imaxlag; /* ... in samples */
int nlag; /* length of error filter in samples */
int ncorr; /* length of corr window in samples */
float *crosscorr; /* right hand side of Wiener eqs */
float *autocorr; /* vector of autocorrelations */
float *spiker; /* spiking decon filter */
float mincorr; /* start time of correlation window */
int imincorr; /* .. in samples */
float maxcorr; /* end time of correlation window */
int imaxcorr; /* .. in samples */
int showspiker; /* flag to display spiking filter */
int showwiener; /* flag to display pred. error filter */
/* Initialize */
initargs(argc, argv);
askdoc(1);
/* Get info from first trace */
if (!gettr(&intrace)) err("can't get first trace");
nt = intrace.ns;
dt = (float)intrace.dt/1000000.0; if (!dt) MUSTGETPARFLOAT ("dt", &dt);
/* Get parameters */
if (!getparint("showwiener", &showwiener)) showwiener = 0;
if (!getparint("showspiker", &showspiker)) showspiker = 0;
if (!getparfloat("pnoise", &pnoise)) pnoise = PNOISE;
if (getparfloat("minlag", &minlag)) iminlag = NINT(minlag/dt);
else iminlag = 1;
if (iminlag < 1) err("minlag=%g too small", minlag);
if (getparfloat("maxlag", &maxlag)) imaxlag = NINT(maxlag/dt);
else imaxlag = NINT(0.05 * nt);
if (imaxlag >= nt) err("maxlag=%g too large", maxlag);
if (iminlag >= imaxlag)
err("minlag=%g, maxlag=%g", minlag, maxlag);
if (getparfloat("mincorr", &mincorr)) imincorr = NINT(mincorr/dt);
else imincorr = 0;
if (imincorr < 0) err("mincorr=%g too small", mincorr);
if (getparfloat("maxcorr", &maxcorr)) imaxcorr = NINT(maxcorr/dt);
else imaxcorr = nt-1;
if (imaxcorr >= nt) err("maxcorr=%g too large", maxcorr);
if (imincorr >= imaxcorr)
err("mincorr=%g, maxcorr=%g", mincorr, maxcorr);
nlag = imaxlag - iminlag + 1;
ncorr = imaxcorr - imincorr + 1;
/* Allocate memory */
wiener = ealloc1float(nlag);
spiker = ealloc1float(nlag);
autocorr = ealloc1float(imaxlag);
/* Set pointer to "cross" correlation */
crosscorr = autocorr + iminlag;
/* Main loop over traces */
do {
static int itr = 0;
++itr;
/* Form autocorrelation vector */
xcor(ncorr, imincorr, intrace.data,
ncorr, imincorr, intrace.data,
imaxlag, 0, autocorr);
/* Leave trace alone if autocorr[0] vanishes */
if (autocorr[0] == 0.0) {
puttr(&intrace);
if (showwiener)
warn("NO Wiener filter, trace: %d", itr);
if (showspiker)
warn("NO spiking decon filter, trace: %d", itr);
continue;
}
/* Whiten */
autocorr[0] *= 1.0 + pnoise;
/* Get inverse filter by Wiener-Levinson */
stoepf(nlag, autocorr, crosscorr, wiener, spiker);
/* Convolve pefilter with trace - don't do zero multiplies */
{ register int i;
for (i = 0; i < nt; ++i) {
register int j;
register int n = MIN(i, imaxlag);
register float sum = intrace.data[i];
for (j = iminlag; j <= n; ++j)
sum -= wiener[j-iminlag] * intrace.data[i-j];
outtrace.data[i] = sum;
}
}
/* Output filtered trace */
memcpy((char*)&outtrace, (char*)&intrace, HDRBYTES);
puttr(&outtrace);
/* Show pefilter and/or spiker on request */
if (showwiener) {
register int i;
warn("Wiener filter, trace: %d", itr);
for (i = 0; i < imaxlag; ++i)
fprintf(stderr, "%10g%c", wiener[i],
(i%6==5 || i==nlag-1) ? '\n' : ' ');
}
if (showspiker) {
register int i;
warn("spiking decon filter, trace: %d", itr);
for (i = 0; i < nlag; ++i)
fprintf(stderr, "%10g%c", spiker[i],
(i%6==5 || i==nlag-1) ? '\n' : ' ');
}
} while (gettr(&intrace));
return EXIT_SUCCESS;
}
int
main(int argc, char **argv)
{
int nt; /* number of points on trace */
float dt; /* time sample interval (sec) */
float *shaper; /* shaping filter coefficients */
float *spiker; /* spiking decon filter (not used) */
float *w; /* input wavelet */
int nw; /* length of input wavelet in samples */
float *d; /* desired output wavelet */
int nd; /* length of desired wavelet in samples */
int nshape; /* length of shaping filter in samples */
float pnoise; /* pef additive noise level */
float *crosscorr; /* right hand side of Wiener eqs */
float *autocorr; /* vector of autocorrelations */
int showshaper; /* flag to display shaping filter */
float f_zero=0.0; /* zero valued item for comparison */
cwp_String wfile=""; /* input wavelet file name */
cwp_String dfile=""; /* desired output wavelet file name */
FILE *wfp; /* input wavelet file pointer */
FILE *dfp; /* desired wavelet file pointer */
/* Initialize */
initargs(argc, argv);
requestdoc(1);
/* Get info from first trace */
if (!gettr(&intrace)) err("can't get first trace");
nt = intrace.ns;
dt = intrace.dt/1000000.0; if (!dt) MUSTGETPARFLOAT ("dt", &dt);
/* Get parameters */
if (!getparint("showshaper", &showshaper)) showshaper = 0;
if (!getparint("nshape", &nshape)) nshape = nt;
if (!getparfloat("pnoise", &pnoise)) pnoise = PNOISE;
/* Open dfile and wfile if they have been getparred */
getparstring("dfile",&dfile);
getparstring("wfile",&wfile);
if ((*dfile=='\0')) { /* if no dfile, then get from command line */
if (!(nd = countparval("d")))
err("must specify d= desired wavelet");
d = ealloc1float(nd); getparfloat("d", d);
} else { /* read from dfile */
if((dfp=fopen(dfile,"r"))==NULL)
err("cannot open dfile=%s\n",dfile);
if (!fgettr(dfp,&dtr)) err("can't get input wavelet");
nd = (int) dtr.ns;
d = ealloc1float(nd);
memcpy((void *) d, (const void *) dtr.data, nd*FSIZE);
}
if ((*wfile=='\0')) { /* then get w from command line */
if (!(nw = countparval("w")))
err("must specify w= desired wavelet");
w = ealloc1float(nw); getparfloat("w", w);
} else { /* read from wfile */
if((wfp=fopen(wfile,"r"))==NULL)
err("cannot open wfile=%s\n",wfile);
if (!fgettr(wfp,&wtr)) err("can't get desired output wavelet");
nw = (int) wtr.ns;
w = ealloc1float(nw);
memcpy((void *) w, (const void *) wtr.data, nw*FSIZE);
}
/* Get shaping filter by Wiener-Levinson */
shaper = ealloc1float(nshape);
spiker = ealloc1float(nshape); /* not used */
crosscorr = ealloc1float(nshape);
autocorr = ealloc1float(nshape);
xcor(nw, 0, w, nw, 0, w, nshape, 0, autocorr); /* for matrix */
xcor(nw, 0, w, nd, 0, d, nshape, 0, crosscorr); /* right hand side */
if (CLOSETO(autocorr[0],f_zero)) err("can't shape with zero wavelet");
autocorr[0] *= (1.0 + pnoise); /* whiten */
stoepf(nshape, autocorr, crosscorr, shaper, spiker);
/* Show shaper on request */
if (showshaper) {
register int i;
warn("Shaping filter:");
for (i = 0; i < nshape; ++i)
fprintf(stderr, "%10g%c", shaper[i],
(i%6==5 || i==nshape-1) ? '\n' : ' ');
}
/* Main loop over traces */
do {
/* Center and convolve shaping filter with trace */
conv(nshape, (nw-nd)/2, shaper,
nt, 0, intrace.data,
nt, 0, outtrace.data);
/* Output filtered trace */
memcpy( (void *) &outtrace, (const void *) &intrace, HDRBYTES);
puttr(&outtrace);
} while (gettr(&intrace));
return(CWP_Exit());
}
