Expanded description
| Topic |
Description |
| Name |
gravred |
| Synopsis |
/infobank/programs/grv/gravred/gravred.for |
| Description |
Program to calculate gravity Free Air Anomaly.
|
| Algorithm |
Observed gravity uses IGSN-71 Datum.
Theoretical gravity is calculated according
to the Chebychev approximation of the 1967 formula
(see theogrv formula toward the end of main program).
If only one valid land tie exists for a cruise,
create a dummy land tie using a fake time and
the same gravity value as the existing tie.
|
| Usage |
. 1st input file = <cruise_id>.14x gravity land tie table
. 2nd input file = <cruise_id>.10x gravity data
. 3rd input file = <cruise_id>.07x navigation data
. output file = <cruise_id>.16x gravity data file
Enter name of input file #1:
Enter name of input file #2:
Enter name of input file #3:
Enter output file name:
Add eotvos to gravity for DMA? (Y,[N])
Enter gravity meter number (02, 26, 32, 36, 41, or 53):
<if imtrid = 41>
Enter gravity meter FILTER LENGTH in decimal minutes:
<if imtrid = 53>
Enter meter constant:
0.9948 - standard for pre 09/14/87 processing
0.9972 - standard for post 09/14/87 processing
|
| Limitations |
The following offset values (in seconds) are assumed:
Meter 02 = 120 (Meter 02 = Meter L2)
Meter 26 = 120
Meter 32 = obtained from gravity input file
Meter 32 (1985) = 180
Meter 36 = 600
Meter 41 = 0 (was 180 or 300)
Meter 53 = 600
|
| Notes |
Include files:
drsvt
|
| Subroutines |
vescinit (shared PMG external)
openem (shared PMG external)
getsymbol (shared PMG external)
percentage (shared PMG external)
yesno (shared PMG external)
getmeter (internal)
getlandtie (internal)
getoffset (internal)
getgravity (internal)
getnav (internal)
|
| Functions |
sin (FORTRAN intrinsic function)
|
| Output |
unit=*(write)
unit=(p)ifilout(write,close)
|
| Input |
unit=(p)ifiltie(close)
unit=(p)ifilgrv(close)
unit=(p)ifilnav(close)
|
| Author |
Clint Steele 12/23/83 .for
Based on program GRVRED.
Carolyn Degnan, 08/28/84
Modified for new times in integer tenths of seconds.
Corrected handling of offset
since gravity time was not being correctly offset.
Finished conversion to integer time from decimal time.
Eliminated unnecessary gotos used for error processing.
Redocumented.
Changed record input section to operate more efficiently.
Ed Maple, 11/27/84
Reduced program to internal subroutines.
Ed Maple, 12/13/84
Changed read format for meter 32 in subroutine GETGRAVITY
to read value in column 108 instead of 106.
Ed Maple, 5/30/85
Changed form4 to default to offset of 180 seconds for meter 32
because 1985 meter 32 has no offsets in the data.
Ed Maple, 6/11/85
Added Powell Meter SL2 to the main program and subroutines.
Meter SL2 is referred to as 02.
B. Blubaugh, 10/21/85
Adjusted offset time for meter 32 and 26.
B. Blubaugh, 2/20/86
Standardized for and ran static analyzer.
C. Degnan, 4/20/87
Added call to PERCENTAGE.
C. Degnan, 6/10/87
Changed meter S-53 constant from 0.9948 to 0.9972 as per Byron
Changed meter S-53 offset to 600 sec as per Byron
C. Degnan, 9/14/87
Changed meter S-53 constant to user's choice because using new value
on previously processed data made faa 30 mgal more than before.
C. Degnan, 4/22/87
Added meter S-36 constant and offset from Dan Hemingson, LaCoste & Romberg.
C. Degnan, 9/6/89
Added prompt and option to add eotvos to gravity for DMA work only.
C. Degnan, 10/1/90
Changed reference from DRS$ to PMG$, CDegnan, 2/19/92
|
| Reads |
read ( 5, cfmtconst ) rconst
read ( ifiltie, cfmttie, iostat = ierr, end = 900 )
* iyr, kda, khr, kmin, ksec, kten, rgrav ( icount + 1 ),
* imtrnum
read ( ifilgrv, cfmtgrv1, iostat = ierr )
* iyr, ida, ihr, imin, isec, iten, rgrav
read ( ifilgrv, cfmtgrv2, iostat = ierr )
* iyr, ida, ihr, imin, isec, iten, rgrav
read ( ifilnav, cfmtnav, iostat = ierr )
* iyr, ida, ihr, imin, isec, iten, rlat, rlong, reotvos,
* rcourse, rspeed
|
| Writes |
write ( ifilout, cfmtout, iostat = ierr )
* iyr, ida, ihr, imin, isec, iten,
* eotvos, grv, theogrv, faa
|
| Calls |
call openem ( 3, 1 )
call yesno ('Y[N]', AddEot)
call getmeter ( imtrid )
call getlandtie
* ( imtrid, itmcntrl, grvcntrl, icntrlcntrl, lvalidmtr )
call getoffset ( imtrid, ioffset )
call getgravity ( imtrid, ioffset, igrvcnt, itmgrv, grv,
* ierr, lendfile )
call getnav ( inavcnt, itmnewnav, eotnew, course,
* speed, xlatnew, xlonnew, ierr, lendfile, iyr )
call adjustgrv
* ( imtrid, igrvcnt, grv, lvalidgrv, rconst )
call converttime ('EXPAND', ida, ihr,
* imin, isec,
* iten, itmgrv, ErrorFlag)
call forerror ( ierr )
call percentage ( 0 )
call forerror ( ierr )
call converttime ('COMPRESS', kda, khr, kmin, ksec,
* kten, itime ( icount ), ErrorFlag )
call converttime ('COMPRESS', 366, 23, 59, 59, 9,
* itime ( 2 ), ErrorFlag )
call percentage ( ifilgrv )
call forerror ( ierr )
call converttime ( 'COMPRESS', ida, ihr, imin,
* isec, iten, itime, ErrorFlag)
call forerror ( ierr )
call converttime ( 'COMPRESS', ida, ihr, imin,
* isec, iten, itime, ErrorFlag)
|
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