PROCESS MUTE
                               ------- ----

Parameters, alphabetically:
addwb     fno       lno       ttp       wbdvel     xtp

Document Date: 27 February 1987

Process MUTE zeroes the beginning of selected traces.  A mute is used to
silence the noise preceding the first arrivals.  Mutes are applied to
marine data to eliminate the water column.  The beginning of the mute is
time zero or the deep water delay.  The user must specify the end time
of the mute.  The mute times may be varied spatially by shot or by rp.
The mutes may be given by trace number or by range (distance from the
shot). The mutes may be given relative to time zero or relative to the
water bottom times.  A 5 sample ramp is applied to the mute window in
order to avoid discontinuities.

Use process SMUTE for surgical mutes (mutes that do not start at 0).
Inner or tail mutes are considered surgical mutes and are done by
process SMUTE.

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

Process MUTE uses the SIOSEIS control point scheme.  See that 
documentation for further information.

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

Example 1: Mute single channel data to the water bottom described via
process WBT.
         mute
            fno 1 ttp 1 0 addwb yes end    # this does all shots!
         end

Example 2: Traces with ranges 500 or less are muted to the water bottom.
Traces with ranges 1000 or greater are muted to the water bottom plus
.5.  Traces with ranges between 500 and 1000 are muted according to
linear interpolation between 0 and .5 plus the water bottom.
         mute
            fno 1 xtp 500 0 1000 .5 addwb yes end
         end


THE PARAMETER DICTIONARY
--- --------- ----------

XTP    - Range-time-pairs.  A list of range and mute time pairs.  Mute
         times for ranges not specified are obtained through linear
         interpolation if the range is between two ranges specified.
         Traces with a range less than the smallest given range will be
         muted to the mute time of the smallest given range.  Likewise,
         ranges larger than the largest given range will be muted to the
         mute time of the largest given range.  XTP must be given with
         increasing ranges.  The program computes the absolute value of
         both user ranges and data ranges.  e.g.
         xtp 1000 3.0 2000 4.0  - Traces with ranges less than 1000 will
         be muted to 3 seconds, traces with ranges greater than 2000
         will be muted to 4 seconds, and traces with ranges between
         1000 and 2000 will be muted proportionately between 3 and 4
         seconds.
         Preset=none

TTP    - Trace number-time-pairs.  A list of trace numbers (of a shot or
         rp) and mute times (listed in pairs).  The mute time for a
         trace between two traces that are specified is obtained through
         linear interpolation of the mute times of the specified traces.
         Traces with a trace number less than the smallest given will be
         muted to the mute time of the smallest trace number.  Likewise,
         traces with a trace number larger than the largest given will
         be muted to the mute time of the largest given.  Ttp must be
         given in increasing trace numbers.  e.g.
         ttp 4 2. 20 5. - Traces 1 thru 4 will be muted to 2 seconds,
         traces 20 and up will be muted to 5 seconds, and traces 5 thru
         19 will be muted proportionately between 2. and 5 seconds.
         Preset=none

ADDWB  - When given a value of YES, the mute times given via XTP or TTP
         will be added to the water bottom time of the trace.  (Water
         bottom times may be entered via process wbt).
         Preset=no

WBDVEL - Water bottom depth to time conversion velocity.  WBDVEL
         indicates that the water bottom depth should be used rather
         than the water bottom time WHEN ADDWB IS GIVEN also.  The
         velocity given should be the two way velocity (e.g. 1500) to
         convert depth to time.  Water depths of zero are considered
         bad or missed and the previous water depth is used.
         WBDVEL is the same as using process wbt and wbt parameter vel.
         Preset = 0     e.g.  addwb yes wbdvel 1500

FNO    - The first shot (or rp) to apply the mutes to.  Shot (rp)
         numbers must increase monotonically.
         Preset=1        e.g. fno 12345

LNO    - The last shot (rp) number to apply the mutes.  LNO must be equal
         to or greater than FNO in each list and must increase list to list.
         Default=fno

END   - Terminates each parameter list.

NOTE *****
1)   Either xtp or ttp must be given.
2)   All times are in seconds.


Written and copyrighted (c) by:
Paul Henkart, Scripps Institution of Oceanography, March 1980
ALL RIGHTS RESERVED.