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ckcov_c

Table of contents
Procedure
Abstract
Required_Reading
Keywords
Brief_I/O
Detailed_Input
Detailed_Output
Parameters
Exceptions
Files
Particulars
Examples
Restrictions
Literature_References
Author_and_Institution
Version
Index_Entries

Procedure

   ckcov_c ( CK coverage ) 

   void ckcov_c ( ConstSpiceChar    * ckfnm,
                  SpiceInt            idcode,
                  SpiceBoolean        needav,
                  ConstSpiceChar    * level,
                  SpiceDouble         tol,
                  ConstSpiceChar    * timsys,
                  SpiceCell         * cover   )

Abstract

   Find the coverage window for a specified object in a specified CK
   file.

Required_Reading

   CELLS
   DAF
   CK
   TIME
   WINDOWS

Keywords

   POINTING
   TIME
   UTILITY


Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   ckfnm      I   Name of CK file.
   idcode     I   ID code of object.
   needav     I   Flag indicating whether angular velocity is needed.
   level      I   Coverage level:  "SEGMENT" OR "INTERVAL".
   tol        I   Tolerance in ticks.
   timsys     I   Time system used to represent coverage.
   cover     I-O  Window giving coverage for `idcode'.

Detailed_Input

   ckfnm       is the name of a C-kernel.

   idcode      is the integer ID code of an object, normally a
               spacecraft structure or instrument, for which pointing
               data are expected to exist in the specified CK file.

   needav      is a logical variable indicating whether only segments having
               angular velocity are to be considered when determining
               coverage. When `needav' is SPICETRUE, segments without
               angular velocity don't contribute to the coverage window;
               when `needav' is SPICEFALSE, all segments for `idcode' may
               contribute to the coverage window.

   level       is the level (granularity) at which the coverage is
               examined. Allowed values and corresponding meanings are:

                  "SEGMENT"    The output coverage window contains
                               intervals defined by the start and stop
                               times of segments for the object
                               designated by `idcode'.

                  "INTERVAL"   The output coverage window contains
                               interpolation intervals of segments for
                               the object designated by `idcode'. For type
                               1 segments, which don't have
                               interpolation intervals, each epoch
                               associated with a pointing instance is
                               treated as a singleton interval; these
                               intervals are added to the coverage
                               window.

                               All interpolation intervals are
                               considered to lie within the segment
                               bounds for the purpose of this summary:
                               if an interpolation interval extends
                               beyond the segment coverage interval,
                               only its intersection with the segment
                               coverage interval is considered to
                               contribute to the total coverage.

   tol         is a tolerance value expressed in ticks of the spacecraft
               clock associated with `idcode'. Before each interval is
               inserted into the coverage window, the interval is
               intersected with the segment coverage interval, then if
               the intersection is non-empty, it is expanded by `tol': the
               left endpoint of the intersection interval is reduced by
               `tol' and the right endpoint is increased by `tol'. Adjusted
               interval endpoints, when expressed as encoded SCLK, never
               are less than zero ticks. Any intervals that overlap as a
               result of the expansion are merged.

               The coverage window returned when tol > 0 indicates the
               coverage provided by the file to the CK readers ckgpav_c
               and ckgp_c when that value of `tol' is passed to them as an
               input.

   timsys      is a string indicating the time system used in the output
               coverage window. `timsys' may have the values:

                   "SCLK"    Elements of `cover' are expressed in encoded
                             SCLK ("ticks"), where the clock is
                             associated with the object designated by
                             `idcode'.

                   "TDB"     Elements of `cover' are expressed as seconds
                             past J2000 TDB.


   cover       is an initialized SPICE window data structure. `cover'
               optionally may contain coverage data on input; on output,
               the data already present in `cover' will be combined with
               coverage found for the object designated by `idcode' in the
               file `ckfnm'.

               If `cover' contains no data on input, its size and
               cardinality still must be initialized.

               `cover' must be declared as a double precision SpiceCell.

               CSPICE provides the following macro, which declares and
               initializes the cell

                  SPICEDOUBLE_CELL        ( cover, COVERSZ );

               where COVERSZ is the maximum capacity of `cover'.

Detailed_Output

   cover       is a SPICE window data structure which represents the
               merged coverage for `idcode'. When the coverage level is
               "INTERVAL", this is the set of time intervals for which
               data for `idcode' are present in the file `ckfnm', merged
               with the set of time intervals present in `cover' on input.
               The merged coverage is represented as the union of one or
               more disjoint time intervals. The window `cover' contains
               the pairs of endpoints of these intervals.

               When the coverage level is "SEGMENT", `cover' is computed
               in a manner similar to that described above, but the
               coverage intervals used in the computation are those of
               segments rather than interpolation intervals within
               segments.

               When `tol' is > 0, the intervals comprising the coverage
               window for `idcode' are expanded by `tol' and any intervals
               overlapping as a result are merged. The resulting window
               is returned in `cover'. The expanded window in no case
               extends beyond the segment bounds in either direction by
               more than `tol'.

               The interval endpoints contained in `cover' are encoded
               spacecraft clock times if `timsys' is "SCLK"; otherwise the
               times are converted from encoded spacecraft clock to
               seconds past J2000 TDB.

               See the -Examples section below for a complete example
               program showing how to retrieve the endpoints from `cover'.

Parameters

   None.

Exceptions

   1)  If the input file has transfer format, the error
       SPICE(INVALIDFORMAT) is signaled by a routine in the call tree
       of this routine.

   2)  If the input file is not a transfer file but has architecture
       other than DAF, the error SPICE(INVALIDARCHTYPE) is signaled
       by a routine in the call tree of this routine.

   3)  If the input file is a binary DAF file of type other than CK,
       the error SPICE(INVALIDFILETYPE) is signaled by a routine in
       the call tree of this routine.

   4)  If the CK file cannot be opened or read, an error is signaled
       by a routine in the call tree of this routine. The output
       window will not be modified.

   5)  If the size of the output window argument `cover' is
       insufficient to contain the actual number of intervals in the
       coverage window for `idcode', an error is signaled by a routine
       in the call tree of this routine.

   6)  If `tol' is negative, the error SPICE(VALUEOUTOFRANGE) is
       signaled by a routine in the call tree of this routine.

   7)  If `level' is not recognized, the error SPICE(INVALIDOPTION)
       is signaled by a routine in the call tree of this routine.

   8)  If `timsys' is not recognized, the error SPICE(NOTSUPPORTED)
       is signaled by a routine in the call tree of this routine.

   9)  If a time conversion error occurs, the error is signaled by a
       routine in the call tree of this routine.

   10) If the output time system is TDB, the CK subsystem must be
       able to map `idcode' to the ID code of the associated spacecraft
       clock. If this mapping cannot be performed, an error is
       signaled by a routine in the call tree of this routine.

   11) If the input CK type is not one of the supported CK types, the
       error SPICE(NOTSUPPORTED) is signaled by a routine in the call
       tree of this routine. This problem may indicate the version of
       the SPICE Toolkit being used is outdated and a new version is
       required.

   12) If any of the `ckfnm', `level' or `timsys' input string
       pointers is null, the error SPICE(NULLPOINTER) is signaled.

   13) If any of the `ckfnm', `level' or `timsys' input strings has
       zero length, the error SPICE(EMPTYSTRING) is signaled.

   14) If the `cover' cell argument has a type other than
       SpiceDouble, the error SPICE(TYPEMISMATCH) is signaled.

Files

   This routine reads a C-kernel.

   If the output time system is "TDB", then a leapseconds kernel
   and an SCLK kernel for the spacecraft clock associated with
   `idcode' must be loaded before this routine is called.

   If the ID code of the clock associated with `idcode' is not
   equal to

      idcode / 1000

   then the kernel variable

      CK_<idcode>_SCLK

   must be present in the kernel pool to identify the clock
   associated with `idcode'. This variable must contain the ID code
   to be used for conversion between SCLK and TDB. Normally this
   variable is provided in a text kernel loaded via furnsh_c.

Particulars

   This routine provides an API via which applications can determine
   the coverage a specified CK file provides for a specified
   object.

Examples

   The numerical results shown for these examples may differ across
   platforms. The results depend on the SPICE kernels used as
   input, the compiler and supporting libraries, and the machine
   specific arithmetic implementation.

   1) Display the interval-level coverage for each object in a
      specified CK file. Use tolerance of zero ticks. Do not
      request angular velocity. Express the results in the TDB time
      system.

      Find the set of objects in the file. Loop over the contents
      of the ID code set: find the coverage for each item in the
      set and display the coverage.


      Example code begins here.


      /.
         Program ckcov_ex1
      ./
      #include <stdio.h>
      #include "SpiceUsr.h"

      int main()
      {

         /.
         Local parameters
         ./
         #define  FILSIZ         256
         #define  MAXIV          100000
         #define  WINSIZ         ( 2 * MAXIV )
         #define  TIMLEN         51
         #define  MAXOBJ         1000

         /.
         Local variables
         ./
         SPICEDOUBLE_CELL        ( cover, WINSIZ );
         SPICEINT_CELL           ( ids,   MAXOBJ );

         SpiceChar               ckfnm   [ FILSIZ ];
         SpiceChar               lsk     [ FILSIZ ];
         SpiceChar               sclk    [ FILSIZ ];
         SpiceChar               timstr  [ TIMLEN ];

         SpiceDouble             b;
         SpiceDouble             e;

         SpiceInt                i;
         SpiceInt                j;
         SpiceInt                niv;
         SpiceInt                obj;


         /.
         Load a leapseconds kernel and SCLK kernel for output time
         conversion.  Note that we assume a single spacecraft clock is
         associated with all of the objects in the CK.
         ./
         prompt_c ( "Name of leapseconds kernel > ", FILSIZ, lsk );
         furnsh_c ( lsk );

         prompt_c ( "Name of SCLK kernel        > ", FILSIZ, sclk );
         furnsh_c ( sclk );

         /.
         Get name of CK file.
         ./
         prompt_c ( "Name of CK file            > ", FILSIZ, ckfnm );

         /.
         Find the set of objects in the CK file.
         ./
         ckobj_c ( ckfnm, &ids );

         /.
         We want to display the coverage for each object. Loop over
         the contents of the ID code set, find the coverage for
         each item in the set, and display the coverage.
         ./
         for ( i = 0;  i < card_c( &ids );  i++  )
         {
            /.
            Find the coverage window for the current object.
            Empty the coverage window each time so we don't
            include data for the previous object.
            ./
            obj  =  SPICE_CELL_ELEM_I( &ids, i );

            scard_c ( 0,  &cover );
            ckcov_c ( ckfnm,       obj,  SPICEFALSE,
                      "INTERVAL",  0.0,  "TDB",       &cover );

            /.
            Get the number of intervals in the coverage window.
            ./
            niv = wncard_c( &cover );

            /.
            Display a simple banner.
            ./
            printf ( "%s\n", "========================================" );

            printf ( "Coverage for object %d\n", (int)obj );

            /.
            Convert the coverage interval start and stop times to TDB
            calendar strings.
            ./
            for ( j = 0;  j < niv;  j++  )
            {
               /.
               Get the endpoints of the jth interval.
               ./
               wnfetd_c ( &cover, j, &b, &e );

               /.
               Convert the endpoints to TDB calendar
               format time strings and display them.
               ./
               timout_c ( b,
                          "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                          TIMLEN,
                          timstr                                    );

               printf ( "\n"
                        "Interval:  %d\n"
                        "Start:     %s\n",
                        (int)j,
                        timstr            );

               timout_c ( e,
                          "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                          TIMLEN,
                          timstr                                    );
               printf ( "Stop:      %s\n", timstr );

            }
            printf ( "%s\n", "========================================" );

         }
         return ( 0 );
      }


      When this program was executed on a Mac/Intel/cc/64-bit
      platform, using the LSK file named naif0010.tls, the SCLK file
      named cas00145.tsc and the CK file named 08052_08057ra.bc, the
      output was:


      Name of leapseconds kernel > naif0010.tls
      Name of SCLK kernel        > cas00145.tsc
      Name of CK file            > 08052_08057ra.bc
      ========================================
      Coverage for object -82000

      Interval:  0
      Start:     2008 FEB 21 00:01:07.771186 (TDB)
      Stop:      2008 FEB 23 22:53:30.001738 (TDB)

      Interval:  1
      Start:     2008 FEB 23 22:58:13.999732 (TDB)
      Stop:      2008 FEB 24 02:22:25.913175 (TDB)

      Interval:  2
      Start:     2008 FEB 24 02:27:49.910886 (TDB)
      Stop:      2008 FEB 24 19:46:33.470587 (TDB)

      Interval:  3
      Start:     2008 FEB 24 19:49:33.469315 (TDB)
      Stop:      2008 FEB 25 04:25:21.250677 (TDB)

      Interval:  4
      Start:     2008 FEB 25 04:29:33.248897 (TDB)
      Stop:      2008 FEB 25 15:23:44.971594 (TDB)

      Interval:  5
      Start:     2008 FEB 25 15:24:12.971396 (TDB)
      Stop:      2008 FEB 25 20:25:04.843864 (TDB)

      Interval:  6
      Start:     2008 FEB 25 20:25:48.843553 (TDB)
      Stop:      2008 FEB 26 00:01:04.752306 (TDB)
      ========================================


   2) Find the segment-level coverage for the object designated by
      `idcode' provided by the set of CK files loaded via a
      metakernel. (The metakernel must also specify leapseconds and
      SCLK kernels.) Use tolerance of zero ticks. Do not request
      angular velocity. Express the results in the TDB time system.

      Use the meta-kernel shown below to load the required SPICE
      kernels.


         KPL/MK

         File name: ckcov_ex2.tm

         This meta-kernel is intended to support operation of SPICE
         example programs. The kernels shown here should not be
         assumed to contain adequate or correct versions of data
         required by SPICE-based user applications.

         In order for an application to use this meta-kernel, the
         kernels referenced here must be present in the user's
         current working directory.

         The names and contents of the kernels referenced
         by this meta-kernel are as follows:

           File name                      Contents
           ---------                      --------
           naif0010.tls                   Leapseconds
           cas00145.tsc                   Cassini SCLK
           08052_08057ra.bc               Orientation for Cassini

         \begindata

           KERNELS_TO_LOAD = ( 'naif0010.tls'
                               'cas00145.tsc'
                               '08052_08057ra.bc')

         \begintext

         End of meta-kernel


      Example code begins here.


      /.
         Program ckcov_ex2
      ./
      #include <stdio.h>
      #include "SpiceUsr.h"

      int main()
      {

         /.
         Local parameters
         ./
         #define  FILSIZ         256
         #define  LNSIZE         81
         #define  MAXCOV         100000
         #define  WINSIZ         ( 2 * MAXCOV )
         #define  TIMLEN         51

         /.
         Local variables
         ./
         SPICEDOUBLE_CELL        ( cover, WINSIZ );

         SpiceBoolean            found;

         SpiceChar               file    [ FILSIZ ];
         SpiceChar               idch    [ LNSIZE ];
         SpiceChar               meta    [ FILSIZ ];
         SpiceChar               source  [ FILSIZ ];
         SpiceChar               timstr  [ TIMLEN ];
         SpiceChar               type    [ LNSIZE ];

         SpiceDouble             b;
         SpiceDouble             e;

         SpiceInt                count;
         SpiceInt                handle;
         SpiceInt                i;
         SpiceInt                idcode;
         SpiceInt                niv;


         /.
         Prompt for the metakernel name; load the metakernel.
         The metakernel lists the CK files whose coverage
         for `idcode' we'd like to determine.  The metakernel
         must also specify a leapseconds kernel and an SCLK
         kernel for the clock associated with `idcode'.
         ./
         prompt_c ( "Name of metakernel > ", FILSIZ, meta );
         furnsh_c ( meta );

         /.
         Get the ID code of interest.
         ./
         prompt_c ( "Enter ID code      > ", LNSIZE, idch );
         prsint_c ( idch,  &idcode );

         /.
         Find out how many kernels are loaded.  Loop over the
         kernels:  for each loaded CK file, add its coverage
         for `idcode', if any, to the coverage window.
         ./
         ktotal_c ( "CK", &count );

         for ( i = 0;  i < count;  i++  )
         {
            kdata_c  ( i,           "CK",     FILSIZ,
                       LNSIZE,      FILSIZ,   file,
                       type,        source,   &handle,     &found );

            ckcov_c  ( file,        idcode,   SPICEFALSE,
                       "SEGMENT",   0.0,      "TDB",       &cover );
         }

         /.
         Display results.

         Get the number of intervals in the coverage window.
         ./
         niv = wncard_c( &cover );

         /.
         Display a simple banner.
         ./
         printf ( "\nCoverage for object %d\n", (int)idcode );

         /.
         Convert the coverage interval start and stop times to TDB
         calendar strings.
         ./
         for ( i = 0;  i < niv;  i++  )
         {
            /.
            Get the endpoints of the ith interval.
            ./
            wnfetd_c ( &cover, i, &b, &e );

            /.
            Convert the endpoints to TDB calendar
            format time strings and display them.
            ./
            timout_c ( b,
                       "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                       TIMLEN,
                       timstr                                  );

            printf ( "\n"
                     "Interval:  %d\n"
                     "Start:     %s\n",
                     (int)i,
                     timstr            );

            timout_c ( e,
                       "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                       TIMLEN,
                       timstr                                  );
            printf ( "Stop:      %s\n", timstr );

         }
         return ( 0 );
      }


      When this program was executed on a Mac/Intel/cc/64-bit
      platform, using the meta-kernel file named ckcov_ex2.tm and
      the NAIF ID "-82000" (Cassini spacecraft bus), the output was:


      Name of metakernel > ckcov_ex2.tm
      Enter ID code      > -82000

      Coverage for object -82000

      Interval:  0
      Start:     2008 FEB 21 00:01:07.771186 (TDB)
      Stop:      2008 FEB 26 00:01:04.752306 (TDB)

Restrictions

   1)  When this routine is used to accumulate coverage for `idcode'
       provided by multiple CK files, the inputs `needav', `level', `tol',
       and `timsys'  must have the same values for all files in order
       for the result to be meaningful.

Literature_References

   None.

Author_and_Institution

   N.J. Bachman        (JPL)
   J. Diaz del Rio     (ODC Space)
   E.D. Wright         (JPL)

Version

   -CSPICE Version 1.0.4, 25-AUG-2021 (JDR)

       Changed input argument name "ck" to "ckfnm" for consistency
       with other routines.

       Edited the header to comply with NAIF standard. Added solutions using
       CASSINI data.

       Extended description of argument "cover" in -Detailed_Input to include
       type and preferred declaration method.

       Added entry #11 and updated entry #2, #3 and #8's short error message in
       -Exceptions section.

   -CSPICE Version 1.0.3, 12-JUL-2016 (EDW)

       Edit to example program to use "%d" with explicit casts
       to int for printing SpiceInts with printf.

   -CSPICE Version 1.0.2, 01-JUL-2014 (NJB)

       Updated index entries.

   -CSPICE Version 1.0.1, 30-NOV-2007 (NJB)

       Corrected bug in first example program in header:
       program now empties result window prior to collecting
       data for each object. Updated examples to use wncard_c
       rather than card_c. Updated second example to demonstrate
       segment-level summary capability.

   -CSPICE Version 1.0.0, 07-JAN-2005 (NJB)

Index_Entries

   get coverage window for ck_object
   get coverage start and stop time for ck_object
   get coverage start and stop time for CK frame
   get coverage start and stop time for CK instrument
Fri Dec 31 18:41:02 2021