NAME
dipf - perform dip (velocity) filtering using optimum mul-
tichannel Wiener design
SYNOPSIS
dipf [ -Nntap ] [ -Ootap ] [ -Dparmfile ] [ -V ] [ -H ] [ -
? ]
DESCRIPTION
dipf essentially performs a multichannel deconvolution. The
dipf filter is computed by considering N channels (or con-
stant x slices) through a model of dipping noise containing
signal at the model origin. The trace-to-trace distribution
of the signal does not enter into the filter computation.
The dip filter is generalized to include a noise fan. Each
off-center channel cuts out a rectangular area equal to the
total magnitude of the noise and the width of the fan is
specified by minimum and maximum dips. An N-channel dipf
filter (where N is an odd integer) is designed to reject the
noise component and pass the desired signal at the origin.
A dip pass filter is easily computed by subtracting the dip
reject filter from a two-dimensional delta function located
at the origin. This filter is then applied to input seismic
data to reject or pass coherent dipping events.
Command line arguments
-N ntap
Enter the full path name of the file containing the
input data set. If not specified, input is expected to
be on the standard input (a pipe into dipf). If no
input file is given, and there is no standard input,
the program will abend.
-O otap
Enter the full path name for the output file to receive
the output data. If no output file is specified, the
program will write the output data to the standard out-
put (a pipe out of dipf).
-D parmfile
File from which processing parameters necessary for
executing dipf are specified. An error message will be
issued if parmfile does not exist. If -D is present on
the command line with no argument, parameters are
assumed to be in-line in the job script marked with the
flag -dipf.crd. By using this method (described in the
startjob section of this manual), the user is allowed
to specify the dipf parameters in-line with the pro-
cessing sequence. This option is also achieved by
omitting the -D flag from the command line and coding
the -dipf.crd flag, followed by the in-line parameter
card images enclosed in double quotes. NOTE: with this
option, startjob must be used to run the script, with
the pipe symbol "|" placed right after the second dou-
ble quote. The parameter cards required for dipf are:
Card Image: data column entries
Column Variable
1-5 card number and name (1DIPF) (not required)
32-33 number of channels in filter (first card only)
should be odd; fewer channels required with large
dips than with small dips.
minimum = 5; maximum = 47; blank or 0 = 15.
for record-squential mode, number of channels
must be less than number of traces/record.
for split-spread mode, number of traces on
either side of the source must be greater than the
number of channels in the filter. If a spread is
encountered during processing in which this normal
condition is not met, zero-valued traces will be
padded to the short side of the spread to
complete processing.
enter on first card only
34-37 filter length (first card only)
length, in samples, of each channel in filter.
minimum = 33; maxmum = 257; blank or 0 = 101.
recommended minimum length =
number of channels * maximum dip.
38-40 BESSEL weighting exponent
exponent of Bessel weighting function applied
spatially; entry of "3" or greater recommended
for small dips; "0", "1", or "2" for large dips.
minimum = 0; maximum = 50; blank or 0 = no Bessel
weighting.
41-45 First Record to filter
number of first record to filter using parameters
on this card; must be greater than "last record"
(cc46-50) on preceding card; successive filters
cannot overlap.
blank or 0 = first record on data set if first
1DIPF card; otherwise, next
unfiltered record.
46-50 Last Record to filter
number of last record to filter using parameters
on this card. record numbers must be in ascending
order.
blank or 0 = last record on data set.
54 water bottom flag
set processing start time of the trace data to the
trace's water bottom time.
blank or 0 = no; 1 = yes.
enter on first card only
55 alias flag
apply aliased dip filter
blank or 0 = no; 1 = yes.
enter on first card only
56 processing mode
blank or 0 = line-sequential (suitable for
stacked data)
1 = record-sequential (used for
unstacked data); filters do not cross
record boundaries; "number of filter
channels" (cc 32-33) must be less than
number of traces/record.
2 = split spread (in direction of
increasing RI's, downdip parameters
apply to last side of spread, traces
with normally positive distances, and
updip parameters apply to the first side,
traces with normally negative distances;
filters do not cross record boundaries).
enter on first card only
58 restore early mute
blank or 0 = yes.
1 = no.
enter on first card only
67 N
signifies new card format
68 Time Variant Application Mode
blank or 0 = None (all times on associated 2DIPF card
ignored
1 = Gated application (filters on associated
2DIPF card(s) applied with 25-samp overlap
betw gates
2 = (pseudo) continuously time-variant appl-
ication (filters on associated 2DIPF crds
are tapered betw input start times; end
time are ignored
Column Variable
1-5 card number and name (2DIPF) (1 per 1DIPF card)
6-10 window start time (ms)
11-15 window end time (ms)
16-20 minimum DOWN dip (ms/trace)
21-25 maximum DOWN dip (ms/trace)
Negative and decimal values are allowed. Down dips
are down in the direction of plotting, i.e. if plot
goes from left to right, down dip is down and to the
right
blank minimum down dip = 0
26-28 noise to signal ratio
applies to DOWN dip only; magnitude of down dipping
noise relative to magnitude of signal.
blank or 0 = 2 if down dips entered; otherwise, 0.
Entry of "2" recommended, but 3-10 may be desirable
if strong noise with large dip is to be rejected.
NOTE 1: the program will issue an error message and
terminate if the up dips, down dips, and associated
noise to signal ratios are all specified as blank or
zero. If the up dips and/or down dips are specified
as blank or zero and their associated noise to signal
ratio is not blank or zero, a flat-dip filter
is generated.
29-33 minimum UP dip (ms/trace)
34-38 maximum UP dip (ms/trace)
Negative and decimal values are allowed. UP dips
are up in the direction of plotting, i.e. if plot
goes from left to right, up dip is up and to the
right
blank minimum down dip = 0
39-41 noise to signal ratio
applies to up dip only; magnitude of updipping
noise relative to magnitude of the signal.
blank or 0 = 2 if up dips entered; otherwise, 0.
Entry of "2" recommended, but 3-10 may be desirable
is strong noise with large dip is to be rejected.
see NOTE 1 above.
42 Filter Type
blank or 0 = dip reject filter
1 = dip pass filter
Note: pas and reject filters are allowed in same job
41-45 Record at Which to Apply Times in cc 6 - 15
Must be > or = to "First Record" on 1DIPF card
(cc41-45) on preceding card
blank or 0 = "First Record" entry on 1DIPF card
46-50 Record at Which to Apply Times in cc 59 - 68
Must be < or = to "Last Record" on 1DIPF card
(cc46-50) on preceding card
order.
blank or 0 = "Last Record" on 1DIPF card
59-63 Start Time (ms)
64-68 End Time (ms)
-V Verbose mode.
Detailed information about the processing parameters is sent to the
output listing device.
-? or -H
Query mode. With this flag, dipf will
send a description of the command line arguments to the
standard error output and stop.
If operating under the Berkeley shell (csh), the -? must be quoted
with single quotes, i.e., '-?'.
BUGS
No trap for running program without an input file and noth-
ing in the standard input.
AUTHOR
Richard Crider (1986) M. A. Miller (1989)
SEE ALSO
startjob(1), Amoco Seismic Information System User Manual
BUGS
A command line option letter and its corresponding argument
may not be separated by whitespace.
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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