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,
The sftahstatic applies a static computed using the sstat and gstat trace
headers. These headers are the source and receiver static in milliseconds.
The program also uses the input parameter sign. The static applied:
This means positive sstat+gstat and sign=1 will shift a trace "up".
Interpolation error is less than 1% for frequencies less than 60% of
the Nyquist frequency.
In this example the cmp sorted prestack data, npr3_gathers.rsf, are
read by sftahread. The headers are in the file npr3_gathers_hdr.rsf,
the headers parameter default. The headers are merged with the trace
amplitudes and the tah data sent down the pipe for statics, nmo, and
stack. The sftahstack program uses both the iline and xline keys to
determine which traces blong to a gather. Using both keys avoids a
problem on edges of a survey when uising xline along may merge gathers
across ilines (a special case that does sometimes happen). sftahwrite
writes the trace data to mappedstack.rsf and the headers are written
to the file mappedstack_hdr.rsf. The order of the data in the output
file is defined by the iline and xline trace headers, so the data
order is (time,xline,iline). Finally, the output volume is displayed
put the history from the input file to the output
flag to control amount of print
0 terse, 1 informative, 2 chatty, 3 debug