Table of Contents

1. GENERAL DESCRIPTION

1.1 PURPOSE OF INTERFACE

This Software Interface Specification (SIS) contains the description of the Light Time File.

1.2 SCOPE

The format and syntax specifications in this SIS apply to all phases of the mission.

1.3 APPLICABLE DOCUMENTS

    SFOC0038-01-09-01     1 May 90    SFOC-1-CDB-ANY-CATALOGUE2

    SFOC0099-01-00       13 Jun 90    Data Dictionary

    SFOC0038-00-08-01    26 Feb 88    SFOC-1-CDB-MGN-TIMESFILE

    SFOC0038-01-09-03     6 Feb 90    SFOC-2-SYS-ANY-TIMEFORMS

                  1 Oct 94    DPTRAJ-ODP User Reference Manual,
                      SOM Vol. 1 and Vol. 2

                  1 Oct 94    DPTRAJ and ODP Interfaces and File
                      Format Descriptions, SOM, Vol. 3

1.4 FUNCTIONAL DESCRIPTION

The Light Time file contains up and down-leg geocentric or topocentric light times for the spacecraft.

1.4.1 Data Source, Destinations, and Transfer Method

Light Time data shall be created on the Navigation computer system. Users of the Light Time File are identified on the cover sheet. Transfer shall be accomplished by making the Light Time file accessible to users within the Central Data Base (CDB). It will be transferred to the CDB via the MOSO LAN.

1.4.2 Pertinent Relationships with Other Interfaces

The generation of this file is dependent upon the spacecraft ephemeris file availability spanning the time over which the Light Time file is desired.

1.4.3 Labeling and Identification

Internal labeling of the Light Time file is accomplished with header records as defined in Section 4.2.

1.4.4 Assumptions and Constraints

N/A.

2. ENVIRONMENT

2.1 HARDWARE CHACTERISTICS AND LIMITATIONS

N/A.

2.2 INTERFACE MEDIUM AND CHARACTERISTICS

Navigation computer file or, at user option, magnetic tape. The MOSO project LAN shall be used as the medium for transmittal of the Light Time File to the Central Data Base (CDB).

2.3 INPUT/OUTPUT PROTOCOLS

N/A.

2.3.1 Device Addressing

N/A.

2.3.2 Operating System Protocols

N/A.

2.3.3 Deformatting

Users of the Light Time file will be required to have software to remove the SFDU data from the file retrieved from the CDB.

2.3.4 Calling Sequence

N/A.

2.4 FAILURE PROTECTION, DETECTION, RECOVERY FEATURES

2.4.1 Backup Requirements

The Navigation Subsystem shall keep the Light Time file in the NAV workstation until it is confirmed as stored within the CDB. Backups will be maintained through normal archiving procedures of the CDB.

Should the CDB malfunction or the network fail, customers of the Light Time File may obtain the file via the secondary method which is to receive the data in TBD form from the NAV Subsystem.

2.4.2 Security/Integrity Measures

Only CDB security/integrity measures will be in effect.

2.5 END-OF-FILE (OR MEDIUM) CONVENTIONS

The end of file is identified by an appropriate record as described in Section 4.2.

2.6 UTILITY PROGRAMS

The utility programs developed by MGSO shall be used to insert and remove the SFDU labels from the Light Time file.

3. DATA FLOW CHARACTERISTICS

3.1 OPERATIONAL CHARACTERISTICS

3.1.1 Generation Method and Frequency

The Light Time data shall be created using the NAV DPTRAJ program LITIME. The start and end dates and times, and the record frequency interval for a file are controlled by the User. Frequency of generation is a project procedural requirement.

3.1.2 Time Span of Product

The time span of the file is controlled by the span of the spacecraft ephemeris input to LITIME and by user input.

3.2 DATA VOLUME

The size of the file depends on the length of the trajectory and upon the user input data interval for which Light Time records are desired.

3.3 FLOW RATE

Flow rate will be limited by the data transfer rate of the MOSO project LAN.

4. DETAILED DATA OBJECT DEFINITION

4.1 STRUCTURE AND ORGANIZATION OVERVIEW

The Light Time File is an ASCII file which consists of the SFDU header, the Light Time File headers, and Light Time File data. Each will be described in the following sections.

4.2 DATA FORMAT AND DEFINITION

4.2.1 SFDU Data Description

The SFDU information and structure, for the Light Time file, (DDID = 0351) in diagramatic representation is as follows:

CCSD3ZS00001AAAAAAAANJPL3KS0L015BBBBBBBB
        MISSION_NAME=***;
        MISSION_ID=*;
        SPACECRAFT_NAME=***;
        SPACECRAFT_ID=**;
        DATA_SET_ID=LIGHTTIME;
        FILE_NAME=ltf.sfdu;
        PRODUCER_ID=NAV;
        APPLICABLE_START_TIME=1981-310T01:00:00.000;
        APPLICABLE_STOP_TIME=1981-312T04:49:00.000;
        PRODUCT_CREATION_TIME=1994-136T14:07:12;
    CCSD3RE00000BBBBBBBBNJPL3IS0****CCCCCCCC

  Substitution in the above is project-dependent as follows:
    Code    Description        Cassini        MGS
    ----    -----------        -------        ---
    *    Mission ID            7        5
    **    Spacecraft ID          82        94
    ***    Mission Name          CASSINI     MARS-GLOBAL-SURVEYOR
    ****     DDID            0351        0351
In the actual Light Time File, the following SFDU data is located at the end of the file, following the non-SFDU data which is described in Section 4.2.2.

    CCSD3RE00000CCCCCCCC
CCSD3RE00000AAAAAAAA

4.2.2 Non-SFDU Data Description

Following is a description of each text record on the file. The Type Flag indicates whether each item is required (R) or optional (O).

Header Record 1

Header record 1 identifies file type/delimits start of header.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
  1-2      "$$"          Control characters signifying        R
                         major control card

   3-6      Mission ID   Key Word - identifies the beginning  R
                         of a file - user input mission code

  13-27     File Header  Identifies the MSS file (default     R
                         is "LIGHT TIME FILE" - IHEAD)

  80       "1"           Record Sequence number               O

Header Record 2

Header record 2 identifies file element name.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-7     File type      Key Word - record type (default      R
                         "LITIME" - IWORLD)    

  13-21     File name      Per file naming conventions        R

    80       "2"           Record Sequence number             O

Header Record 3

Header record 3 specifies name and extension of person preparing file.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-7      "PREP"        Key Word - identifies record type    R

 13-21    Name/ext.      Name and extension of preparer       O

  80       "3"           Record Sequence number               O

Header Record 4

Header record 4 specifies the title of the LITIME File.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-6     "TITLE"        Key Word - identifies record type    R

 13-72    Title          Any alphanumeric characters          O

  80       "4"           Record Sequence number               O

Header Record 5

Header record 5 specifies the spacecraft ID.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-5     "SCID"         Key Word - identifies record type    R

  13      S/C ID         Single alphanumeric character        O

  80       "5"           Record Sequence number               O

Header Record 6

Header record 6 specifies the run ID of the program creating the file.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1      "*"            Header character                     R

  2-5     "RUNID"        Key Word - identifies record type    R

 13-18    RUN ID         Run ID of generating program         O

  80      "6"            Record Sequence number               O

Header Record 7

Header record 7 specifies the JPL local file creation time.

Column    Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-9     "CREATION"     Key Word - identifies record type    R

 13-15    "JPL"          Defines time base                    O

 17-18     Year          Last two digits of the year          O

  19      "-"            Separator                            O

 20-22    Day of year    Integer                              O

  23       "/"           Separator                            O

 24-25     Hours         Integer (24-hour clock)              O

  26      ":"            Separator                            O

 27-28    Minutes        Integer                              O

  29       ":"           Separator                            O

 30-31     Seconds       Integer                              O

  80       "7"           Record Sequence number               O

Header Record 8

Header record 8 specifies the SCE and ERT start time of file coverage.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-6     "BEGIN"        Key Word - identifies record type    R

 13-15    "SCE"          Defines time base (UTC)              R

 17-18     Year          Last two digits of the year          R

  19      "-"            Separator                            R

 20-22    Day of year    Integer                              R

  23       "/"           Separator                            R

 24-25     Hours         Integer (24-hour clock)              R

  26      ":"            Separator                            R

 27-28    Minutes        Integer                              R

  29       ":"           Separator                            R

 30-35     Seconds       Seconds (Decimal with fractions      R
                         to millisecond precision)

 38-40    "ERT"          Defines time base (ET)               R

 42-60    ERT time       Time in same format as columns 17-35 R

   80     "8"            Record Sequence number               O

Header Record 9

Header record 9 specifies the SCE cutoff time of file coverage.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-7     "CUTOFF"       Key Word - identifies record type    R

  13-35   See record 8   SCE time (UTC)                       R

  80      "9"            Record Sequence number               O

Header Record 10

Header record 10 specifies the trajectory data base for the run.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "*"           Header character                     R

  2-6     "PFILE"        Key Word - identifies record type    R

 13-24    Trajectory     A TED identifier                     R

 79-80    10             Record Sequence number               O

Header Record 11 to N

Header records 11 to N are additional optional records provided to
permit for user header comments (N<14).

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
   1       "'"           Header character                     R

  2-72    Comments       Any alphanumeric data                O

 73-80    RSN            Record Sequence number               O

Last Header Record

The last header record delimits the end of the header/start of data records .

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
 1-2       "$$"          Characters signifying major          R
                         control card

 3-5      "EOS"          Key Word - identifies end of header  R

 73-80    RSN            Record Sequence number               O

Data Records

Data records specifies the SCE time and the corresponding upleg and downleg.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
 1-2       Year          Last two digits of the year          R

  3       "-"            Separator                            R

 4-6      Day of year    Integer                              R

  7        "/"           Separator                            R

 8-9      Hours          Integer (24-hour clock)              R

 10       ":"            Separator                            R

11-12     Minutes        Integer                              R

 13       ":"            Separator                            R

14-15     Seconds        Integer                              R

30-39     Downleg        Decimal seconds (millisecond         R
          (DLT)          precision, right justified,
                         blank filled)

45-54     Upleg          Decimal seconds (millisecond         R
          (ULT)          precision, right justified,
                         blank filled

57-58     Station #      DSN Station number for this record   R
                         (03 for geocentric)

60-71     Run Time       Run time of run which created record O

 72       S/C ID         Single alphanumeric character        O

73-80     RSN            Record Sequence number               O

Last File Record

The last file record delimits the end of file.

Columns   Content        Description                       Type Flag
--------------------------------------------------------------------
 1-2      "$$"           Characters signifying                R
                         major control card

 3-5      "EOF"          Key Word - identifies end of file    R

 73-80    RSN            Record Sequence number               O

Appendix: SAMPLE WRAPPED FILE

A sample wrapped Light Time File is provided in order to show the expected format of the data. The user should not code specifically to the real numbers as printed.

CCSD3ZS00001AAAAAAAANJPL3KS0L015BBBBBBBB
MISSION_NAME=CASSINI;
MISSION_ID=7;
SPACECRAFT_NAME=CASSINI;
SPACECRAFT_ID=82;
DATA_SET_ID=LIGHTTIME;
FILE_NAME=litime.sfdu;
PRODUCER_ID=NAV;
APPLICABLE_START_TIME=1981-310T01:00:00.000;
APPLICABLE_STOP_TIME=1981-312T04:49:00.000;
PRODUCT_CREATION_TIME=1994-136T14:07:12;
CCSD3RE00000BBBBBBBBNJPL3IS00351CCCCCCCC
$$PIONEER   LIGHT TIME FILE                                                    1
*LITIME     OWLTP(  )                                                          2
*PREP       John E. Ekelund                                                    3
*TITLE      Light Time File for S/W Testing                                    4
*SCID       82                                                                 5
*RUNID      Enter LITIME 16-MAY-1994 14:07:12 linked 15-NOV-1993 14:1          6
*CREATION   JPL 94-136/14:07:12                                                7
*BEGIN      SCE 81-310/01:00:00.000  ERT 81-310/01:06:44.167                   8
*CUTOFF     SCE 81-312/04:49:00.000                                            9
*PFILE                                                                        10
'P file is [JEE.CASES]P016J2A.NIO                                             11
'     SCE                     DOWN-LEG        UP-LEG         RUN TIME  S      12
$$EOS                                                                         13
81-310/01:00:00                 351.977        351.926  14 940516140712P      14
81-310/01:00:00                 351.971        351.921  43 940516140712P      15
81-310/01:00:00                 352.003        351.952  63 940516140712P      16
81-310/07:00:00                 350.973        350.922  14 940516140712P      17
81-310/07:00:00                 350.940        350.889  43 940516140712P      18
81-310/07:00:00                 350.973        350.923  63 940516140712P      19
81-310/13:00:00                 350.007        349.957  14 940516140712P      20
81-310/13:00:00                 349.990        349.939  43 940516140712P      21
81-310/13:00:00                 349.982        349.932  63 940516140712P      22
81-310/19:00:00                 349.059        349.009  14 940516140712P      23
81-310/19:00:00                 349.070        349.020  43 940516140712P      24
81-310/19:00:00                 349.060        349.009  63 940516140712P      25
81-311/01:00:00                 348.183        348.133  14 940516140712P      26
81-311/01:00:00                 348.177        348.128  43 940516140712P      27
81-311/01:00:00                 348.209        348.158  63 940516140712P      28
81-311/07:00:00                 347.181        347.131  14 940516140712P      29
81-311/07:00:00                 347.148        347.098  43 940516140712P      30
81-311/07:00:00                 347.181        347.132  63 940516140712P      31
81-311/13:00:00                 346.216        346.167  14 940516140712P      32
81-311/13:00:00                 346.200        346.149  43 940516140712P      33
81-311/13:00:00                 346.192        346.142  63 940516140712P      34
81-311/19:00:00                 345.268        345.219  14 940516140712P      35
81-311/19:00:00                 345.279        345.230  43 940516140712P      36
81-311/19:00:00                 345.269        345.219  63 940516140712P      37
81-312/01:00:00                 344.390        344.340  14 940516140712P      38
81-312/01:00:00                 344.384        344.335  43 940516140712P      39
81-312/01:00:00                 344.415        344.365  63 940516140712P      40
$$EOF                                                                         41
CCSD3RE00000CCCCCCCCCCSD3RE00000AAAAAAAA

Revision date: 15 April 1996

For information about this on-line document, contact Vic Legerton
For information about the file described by this document, contact John Ekelund