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!
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!
! SDDL Name:	ORBFIT_CONTROL.SDDL
!
! Purpose:      This file defines the "orbfit_control" relation. 
!
! Modification History:
!
!   Date       PR      Who                       Reason
! --------   -------   ---   -------------------------------------------------
! 09/09/99   33723     sss   Original Version
!
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!

LANGUAGE  C, SQL

INCLUDE  ZSPSS_USER_TYPES.SDDL

RECORD  orbfit_control_type

    DESCRIPTION         "This relation contains HST and TDRS ephemeris 
                         least squares fit parameters to control the 
                         fitting process.  The ORBFIT/CREATE program
                         uses these parameters to fit the HST/TDRS ephemeris
                         data into a curve loaded into relation fit_cat. 
                       
                         Columns 'arg_lat', 'orb_radius', 'ra_asc_node',
                         and 'inclination' define solve for flags (T=true,
                         F=false).  There are seven terms per column.
                         The first three terms are a Taylor series in time 
                         truncated at 2nd order. The last four are a Fourier 
                         expansion to 2nd order.
                         
                         The Taylor series will give the long term behavior 
                         of the fit (so-called 'secular' or aperiodic behavior),
                         while the Fourier terms give the effect of any 
                         repeating deviation of the ephemeris points from a 
                         circular orbit. An excellent degree of accuracy
                         can be obtained using a first order Taylor expansion
                         for the time varying orbital longitude (F1) and the 
                         longitude of the ascending node (F3) and a zeroth 
                         order Taylor expansion for the radius (F2) and the 
                         inclination (F4). Second order Taylor and all Fourier 
                         terms can be ignored.
                         
                         For more information on the fit model, see Appendix B, 
                         SE-06-02."
                         

    FIELD  name      
        DESCRIPTION     "Name of the fit control parameters.  This value
                         is specified in the ORBFIT/CREATE /CONTROL qualifier."
        TYPE            C*15
    END_FIELD


    FIELD  fit_rate
        DESCRIPTION     "Fit rate selects every N'th point for calculating 
                         the fit."
        TYPE            I*4
    END_FIELD


    FIELD  test_rate
        DESCRIPTION     "Test rate selects every N'th point for testing
                         a calculated point against the fit."
        TYPE            I*4
    END_FIELD
   

    FIELD  fit_model
        DESCRIPTION     "The Fit Model may = 'Q' for quadratic or 'L' for 
                         linear."
        TYPE            C*1
    END_FIELD
    

   FIELD  arg_lat      
        DESCRIPTION     "Seven solve for flags (T=True, F=False) for the
                         orbital longitude term (F1).  See the relation 
                         description for more information."
        TYPE            C*7
    END_FIELD
    

    FIELD  orbradius      
        DESCRIPTION     "Seven solve for flags (T=True, F=False) for the
                         orbital radius term (F2).  See the relation 
                         description for more information."
        TYPE            C*7
    END_FIELD


    FIELD  asc_node      
        DESCRIPTION     "Seven solve for flags (T=True, F=False) for the
                         right ascension of the ascending node term (F3).
                         See the relation description for more information."
        TYPE            C*7
    END_FIELD


    FIELD  incline      
        DESCRIPTION     "Seven solve for flags (T=True, F=False) for the
                         orbital inclination term (F4).  See the relation 
                         description for more information."
        TYPE            C*7
    END_FIELD

END_RECORD


RELATION  orbfit_control

    TYPE             orbfit_control_type

    DESCRIPTION      "ST and TDRS Ephemeris Fit Control Parameter Relation"

    SUBSYSTEM_USING  "SPSS"

    INDEX  orbfit_control_1
        TYPE         unique, clustered
        FIELDS       name
    END_INDEX

END_RELATION


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