Least Squares Scope Functions

CAgAttr GetStateContents()

This function previews which states will be used by a least squares process. For least squares processes with multiple stages, this will reflect the states for the first stage. The StateContent tool calls this function.

Return Value

CAgAttr

A list of states (as a list of strings) applicable to the simulator

Example VBS:

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Set stateList = sc. Satellite("Sat1").LeastSquares("LS1").GetStateContents

bool Go()

Use this to run the Least Squares process.

Return Value

bool

Always true

Example VBS:

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bSuccess = sc.Satellite(0).LeastSquares(0).Go

It also returns a flag indicating if the LeastSquares ran and if the subsequent ephemeris prediction propagated to the requested stop time. To distinguish between the LeastSquares run itself and the ephemeris prediction, you can inspect the following attributes with detailed status/error information:

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LeastSquares.RunResults.NumMeasProcessed = <int>
LeastSquares.RunResults.NumMeasRejected = <int>
LeastSquares.RunResults.NumMeasSkipped = <int>
LeastSquares.RunResults.SetupSuccess = <bool>
LeastSquares.RunResults.RunSuccess = <bool>
LeastSquares.RunResults.RunCanceled = <bool>
LeastSquares.RunResults.MaxIterationsExhausted = <bool>
LeastSquares.RunResults.PropagatorError = <bool>
LeastSquares.RunResults.EphemerisPredictPropagatorError = <bool>
LeastSquares.RunResults.PropagatorAltitudeError = <bool>
LeastSquares.RunResults.PropagatorVelocityError = <bool>
LeastSquares.RunResults.PropagatorStateVectorError = <bool>
LeastSquares.RunResults.PropagatorErrorSatelliteName = <string>
LeastSquares.RunResults.PropagatorErrorTime = <time>
LeastSquares.RunResults.FinalRMS
LeastSquares.RunResults.DivergenceDetected

bool SetEditedResiduals(string inputs, string date, integer ntype, double dvalue)

This is a helper function for the graphical residual editing capability. It enables graphical residual editing to work properly in cases where multiple observations of the same type from the same sensor exist for the same satellite at identical times. This function updates the ResidualEditing Schedule.

Parameters

inputs string

Contains the following items separated by spaces:

  • emitter ID (-1 if not set)

  • strand

  • tracker

  • satellite

  • measurement type
date string The date string with units
ntype int The type of measurement
dvalue double The measurement value

Return Value

bool

A Boolean indicating whether or not an entry is valid

Example VBS:

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inputs = "-1 TrackingSystem1.Facility1 - * TrackingSystem1.Facility1 Satellite1 Range "
dString = "01 Jul 2008 13:44:00 UTCG"
nype = 1
double_value = 1420193.763369
bSuccess = sc.Filter(0).SetEditedResiduals(inputs, dString, ntype, double_value)

bool Stop()

Use this to stop the current running Least Squares process.

Return Value

bool Always true

Example VBS:

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bResult = sc.Satellite(0).LeastSquares(0).Stop

bool Transfer()

Use this to transfer the Least Squares solution to the parent satellite.

Return Value

bool False if there is no solution to be transferred

Example VBS:

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bResult = sc.Satellite(0).LeastSquares(0).Transfer

bool IODLS(double longRange, double longStep, double Initiala, double Initiale, double Initialu, douible Initiali, double InitialO, double Initialw, string reportFilename)

This is a helper function to the GEO_IODLS utility, which performs GEO initial orbit determination (IOD) using a Least Squares (LS) search algorithm. It makes a one-dimensional search in GEO Mean Longitude until it achieves LS convergence with an orbit estimate that falls within the GEO orbit class. To use this utility/function, you need a scenario containing the GEO satellite of interest, a Least Squares object attached to the GEO, and tracking system information. You should set up the scenario just as if you were running a LS on the GEO, including setting up of the LS stage data. The only difference is that the white panel satellite initial orbit estimate is ignored and replaced by the initial estimates input in the calling list. However, the white panel satellite state epoch time is used as the epoch for the initial conditions.

Parameters

longRange double

Specify the positive/negative range for the mean longitude search. If you enter 10000 for Initialu, then the range of the longitude search will be computed based on tracker locations.
longStep double Specify the mean longitude search step. Let L0 be initial mean longitude for the search. Then the search order will be L0, L0 + longStep, ,L0 - longStep, L0 + 2*longStep, ... until either n*longStep > longRange or convergence is achieved.
Initiala double Enter the initial semimajor axis estimate in kilometers.
Initiale double Enter the initial eccentricity estimate.
Initialu double Enter the initial argument of latitude estimate in deg. If you enter 10000, then an initial argument of latitude estimate is computed based on tracker locations.
Initiali double Enter the initial inclination estimate in degrees.
InitialO double Enter the initial node estimate in degrees.
Initialw double Enter the initial argument of perigee estimate in degrees.
reportFilename string Provide the path to the IODLS file.

Return Value

bool

A Boolean indicating whether or not an entry is valid

Example VBS:

In this example, IODLS computes a starting true argument of latitude based on tracker locations:

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filename = "c:\tmp\iodls.txt"
ls = sc.Satellite("GEOSatellite1").LeastSquares("LeastSquares1")
bResult = ls.IODLS(90, 10, 42164, 0.005, 10000, 0, 0, 0, filename)

Example VBS:

In this example, inputs for the initial true argument of latitude estimate are from the user:

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filename = "c:\tmp\iodls.txt"
ls = sc.Satellite("GEOSatellite1").LeastSquares("LeastSquares1")
bResult = ls.IODLS(90, 10, 42164, 0.005, 80, 0, 0, 0, filename)