SAC Command Reference Manual: SSS

Signal Stacking Subprocess


A subprocess is like a small program within the main SAC program. You start a subprocess by typing its name (SSS in this case.) You can terminate it and return to the main program using the quitsub command. You can also terminate SAC from within a subprocess using the QUIT command.

While within a subprocess, you can execute any command belonging to that subprocess plus a limited number of main SAC commands.

SSS is a package for doing signal stacking (i.e. summation or beamforming).

Each signal (i.e. SAC file) has properties such as a static delay, epicentral distance, weighting factor, and polarity associated with it. The dynamic delays can be calculated using a normal moveout or refracted wave velocity model.

Certain delay properties can be automatically incremented between summations. Files are easily added to or removed from the stack file list. The time window for the stack is easily adjusted. Files which do not contain data throughout the stack time window are filled with zeros.

The stack file list can be plotted with or without the summation. Each summation can be saved on disk for later use. A record section plot is also included in this subprocess.

The SS commands are listed below in alphabetical order. A list of the allowed main SAC commands is also shown. You can also use all of the SAC macro features in this subprocess.

SSS Commands

ADDSTACK:Add a new file to the stack file list.
CHANGESTACK:Change properties of files currently in the stack file list.
DELETESTACK:Deletes one or more files from the stack file list.
DELTACHECK:Change the sampling rate checking option.
DISTANCEAXIS:Define the record section plot distance axis parameters.
DISTANCEWINDOW:Controls distance window properties on subsequent record section plots.
GLOBALSTACK:Sets global stack properties.
INCREMENTSTACK:Increments properties for files in the stack file list.
LISTSTACK:Lists the properties of the files in the stack file list.
 Plots a record section of the files in the stack file list.
PLOTSTACK:Plots the files in the stack file list.
QUITSUB:Terminates the Signal Stacking Subprocess.
SUMSTACK:Sums the files in the stack file list.
TIMEAXIS:Controls the time axis properties on subsequent record section plots.
TIMEWINDOW:Sets the time window limits for subsequent stack summation.
SSSTRAVELTIME:Function traveltime called from within SSS.Computes traveltime curves for pre-defined models
VELOCITYMODEL:Sets stack velocity model parameters for computing dynamic delays.
VELOCITYROSET:Controls placement of a velocity roset on subsequent record section plots.
WRITESTACK:Writes a stack summation to disk.
ZEROSTACK:Zeros or reinitializes the signal stack.

Main SAC Commands

This is a list of the allowed main SAC commands. Their abbreviated names are also allowed.

COMCOR           COPYHDR          DATAGEN
ERASE            EVALUATE         FLOOR
GETBB            GRID             GTEXT
LINE             LINLIN           LINLOG
LOGLAB           LOGLIN           LOGLOG
MACRO            MESSAGE          PAUSE
PLABEL           PLOTC            QDP
QUIT             READBBF          REPORT
SETMACRO         SGF              SYMBOL
TITLE            TSIZE            VSPACE
WAIT             WINDOW           WRITEBBF
XDIV             XFUDGE           XFULL
XGRID            XLABEL           XLIM
XLIN             XLOG             XVPORT
YDIV             YFUDGE           YFULL
YGRID            YLABEL           YLIM
YLIN             YLOG             YVPORT