sftahpef (2.0-git)
index
user/karl/Mtahpef.c
Trace And Header Prediction Error Filtering

 
Synopsis
        sftahpef < inp.rsf > out.rsf wiener=wien.rsf mix= verbose=1 minlag= maxlag= pnoise=0.001 nmix=1 mincorr= maxcorr=

tah is the abbreviation of Trace And Header. Madagascar programs
that begin with sftah are a designed to:
1- read trace and headers from separate rsf files and write them to
standard output (ie sftahread)
2- filter programs that read and write standard input/output and
process the tah data (eg sftahnmo, sftahstack)
3- read tah data from standard input and write separate rsf files for
the trace and headers data (ie sftahwrite)

These programs allow Seismic Unix (su) like processing in Madagascar.
Some programs have su like names.

Some programs in this suite are sftahread, sftahgethw, ftahhdrmath,
and sftahwrite.

The sftahpef applies prediction error filtering (often called decon)

EXAMPLE:

sftahsort //
verbose=0 input=npr3_field.rsf sort='fldr:214,254,10 tracf' //
| sftahwindow ns=2047 //
| sftahgain tpow=2 //
| sftahmute tmute=-.200,-.050,.200,3.00 xmute=0,880,1760,18000 //
ntaper=80 //
| sftahpef //
verbose=1 minlag=.002 maxlag=.1 pnoise=.01 mincorr=0 maxcorr=3 //
| sftahagc wagc=1.000 verbose=1 //
| sftahwrite verbose=1 mode=seq output=pefshots.rsf //
>/dev/null

sfgrey
In this example unprocessed field traces are read by sftahsort from
the npr3_field.rsf file. sftahsort was used select just a 5 shotpoints
(fldr 214 to 254 incrementing by 10) from a large dataset. The headers
are in the file npr3_filed_hdr.rsf, the headers parameter default.
The headers are merged with the trace amplitudes and the tah data sent
down the pipe for further processing.

sftahwindow selects the first 2047 trace amplitudes. The last two
samples on this data were bad, and are elliminated from further
processing.

sftahgain multiplies the traces by time squared (t**2). This
approximately compensates for spreading loss that makes amplitude at
large time smaller than amplitude at small time.

sftahmute is applied to elliminate the data at small time/offset.

sftahpef applies prediction error filtering (or decon). A prediction
gap or .002 seconds, or one sample) makes this decon "spiking" decon.
A three seconds window si selected to compute the autocorrelation and
a .1 second filter is computed and applied.

After decon a 1 second agc was applies using the sftahagc.

Data is written to the output file, pefshots.rsf, using sftahwrite.
Traces headers are written to pefshots_hdr.rsf. The output file data
order is sequential, or just in the order sftahwrite reads them from
standard input.


 
Parameters
       
 
float maxcorr=
end of autocorrelation window in sec
 
float maxlag=
last lag of prediction filter (sec)
 
float mincorr=
start of autocorrelation window in sec
 
float minlag=
first lag of prediction filter (sec)
 
floats mix=
weights for moving average of the autocorrelations [nmix]
 
int nmix=1
number of weights (floats) for moving averages
 
float pnoise=0.001
relative additive noise level
 
int verbose=1


flag to control amount of print
0 terse, 1 informative, 2 chatty, 3 debug

 
string wiener=
file to output Wiener filter (auxiliary output file name)

 
Used In
       

 
DATA
        teapotdome/firstlook
viking/decon