Document Date: 6 July 1981 

	Process ACORR computes the one-sided autocorrelation function of
a trace.  Only positive lags of the autocorrelation are computed and
output.  If more than one autocorrelation window is specified on each
trace, each output trace is the concatenation of all the autocor-
relations for that  trace.  Thus, the output length is the sum of the
lengths of the individual windows.

More than one autocorrelation window may be given for each trace. The
windows may be spatially varied by shot or rp or by hanging the windows
on the water bottom.  

All parameters that remain constant for a set of shots (rps) may be 
described in a parameter set FNO to LNO.  Windows between two parameter 
sets are calculated by linearly interpolating between LNO of one set 
and FNO of the next set.

Each parameter list must be terminated with the word END.  The entire 
set of ACORR parameters must be terminated by the word END.

THE PARAMETER DICTIONARY
--- --------- ----------
  
SETS  - Start-end time pairs defining the autocorrelation windows.
        Times are in seconds and may be negative when hanging the
        windows from the water bottom.  A maximum of 5 windows 
        may be given.
        Required.    e.g. sets 0 1 

OLENS - The output autocorrelation lengths in seconds.  This 
        corresponds to  the normal use of the number of lags to 
        compute, but is in units of seconds.  Each autocorrelation
        has it's own length.  A maximum of 5 lengths may be given.
        required.    e.g. olens .5

ADDWB - When given a value of yes, the windows given via sets will
        be added to the water bottom time of the trace.  
        (Water bottom times may be entered via process wbt).
        preset=no     e.g. addwb yes

FNO   - The first shot (or rp) to autocorrelate.  Shot (rp) numbers must
        increase monotonically.
        preset=1

LNO   - The last shot (rp) number to autocorrelate.  LNO must be larger
        than FNO in each list and must increase from list to list.
        default=fno

END   - Terminates each parameter list.

Written and copyrighted (c) by:
Paul Henkart, Scripps Institution of Oceanography, July 1981