Simulator Scope Functions

The Simulator attribute scope contains functions that enable you to interact with a Simulator object.

CAgAttr ClearIntervals(string satName, string trkName)

This function clears simulation intervals for either a given satellite or tracker or both. STKIntFileTool and LoadSimulationIntervals HTML pages call this function.

Parameters

satName string Enter the string name of the satellite. An empty string ("") is interpreted to mean any object.
trkName string Enter the string name of the tracker. An empty string ("") is interpreted to mean any object.

Return Value

CAgAttr A Boolean indicating whether or not it performed any action

Example VBS:

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bFlag = sc.Simulator(0).CustomDataEditing.ClearIntervals("","BOSS-A")

CAgAttr GetStateContents()

This previews which states the simulator will use. 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.Simulator(0).GetStateContents

bool Go()

Use this to run the simulator.

Return Value

CAgAttr A Boolean that is true if there are no errors initiating the simulator

Example VBS:

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bSuccess = sc.Simulator(0).Go

CAgAttr ImportIntervals(string filename, double dt, string satName, string trkName)

Use this to import intervals from an STK Intervals File, which will add or append entries in the simulator's CustomTrackingIntervals Schedule. The STKIntFileTool and LoadSimulationIntervals HTML pages call this function.

Parameters

filename string The file path containing the intervals
dt double The time step, in seconds
satName string Can be a specific satellite or "All Satellites", or use "" to get the satellite names from the interval file
trkName string Can be a specific tracker or "All Trackers", or use "" to get the tracker names from the interval file

Return Value

CAgAttr A Boolean indicating success or not

Example VBS:

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intervals = sc.Simulator(0).CustomTrackingIntervals
bSuccess = intervals.ImportIntervals("c:\tmp\StkIntervals.int", 15.0, _
                                     "All Satellites", "All Trackers")

CAgAttr SimulateDeltaDOR(const string& startString, const string& stopString, int numDDOR, double slewTime, double interSeqTime, const string& facility1String, const string& facility2String, const string& satelliteString, int quasarID, double quasarDirTol, const string& refEphFileName, const string& observationFileName, const string& detailsFileName, bool addToScenarioMeasFilesList)

This function generates simulated Differenced One-way Range (DOR) and Quasar Differenced One-Way Range (QuasarDOR) measurements, based on a specified reference ephemeris, and writes them to a generic observation format file (.gobs). You can then read the DOR and QuasarDOR measurements back into the ODTK application to create DeltaDOR measurements for use in estimation. The first specified tracking station must contain measurement statistics for DOR and QuasarDOR measurement types. The function uses the white noise settings for the DOR and QuasarDOR measurement types in the generation of random variation to the computed measurement values based on the Simulator object setting for inclusion of white noise. The function will not generate or include time-correlated measurement biases based on the stochastic model definition in the reported measurement values. The number of measurements written will appear in the message viewer.

The function generates observations in sequences. A sequence contains an odd number of observations and takes the form Q-S-Q-S-Q-S-Q, where Q designates a QuasarDOR measurement and S designates a DOR measurement. The function generates one sequence during a viewing opportunity.

The Facility1 object must contain the appropriate measurement statistics for the DOR and QuasarDOR measurement types for simulation to be successful. Facility1 must also contain DeltaDOR measurement statistics in order to process measurements.

Parameters

startString string Enter the time to start simulated observation generation.
stopString string Enter the time to stop simulated observation generation.
numDDOR int Enter the desired number of DeltaDOR observations that the function can generate from an observation sequence. For example, the function can use a Q-S-Q-S-Q-S-Q to generated three DeltaDOR observations, one from each Q-S-Q combination.
slewTime double Specify the time between spacecraft and quasar observations inside an observation sequence, in seconds.
interSeqTime double Specify the minimum time between observation sequences, in seconds.
facility1String string Enter the name of the facility object containing the measurement statistics for the DOR and QuasarDOR measurements.
facility2String string Enter the name of the second facility object in the DOR baseline.
satelliteString string Enter the name of the satellite.
quasarID int Enter the integer ID for a quasar that the function will use in the generation of the QuasarDOR measurements. IDs must be resolvable by the information in the file identified by the QuasarDatabaseFilename in the scenario properties. You can specify the quasar ID as zero to have ODTK processing automatically select a quasar near the line of sight to the spacecraft for each observation sequence.
quasarDirTol double Enter the quasar direction tolerance, given in degrees. It sets the maximum angle for how far off the line of the sight to the spacecraft to a quasar can be for the function to include it in the generation of QuasarDOR measurements. The function uses this when quasarID is set to zero.
refEphFileName string Enter the path of the ephemeris file in STK format (.e) that contains the trajectory of the satellite.
observationFileName string Enter the path of the output observation file, (.gobs) format, into which the function writes the generated DOR and QuasarDOR observations.
detailsFileName string Enter the path of an optional text file to which the function writes details about the measurement generation, including the quasar IDs. You can omit this or specify it as an empty string if you do not want this file.
addToScenarioMeasFileList bool (Optional) Provide a Boolean indicating if the function should add the generated measurement file to the list of measurement files in the Scenario properties. The default is true.

Return Value

The function returns a CAgAttr object containing the following properties:

Succeed CAgAttrBool This returns true if successful.
Messages CAgAttrString This provides informational or error messages to display in the status line.
QuasarID CAgAttrInt This returns the ID of the quasar used in the first observation sequence.
NumSequencesGenerated CAgAttrInt This returns the number of QDOR/DOR sequences generated.
NumObservationsGenerated CAgAttrInt This returns the number of QDOR + DOR observations generated.
NumTripletsGenerated CAgAttrInt This returns the number of Q-S-Q triplets generated. The function converts each triple to one DeltaDOR measurement during estimation.

Example VBS:

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Dim Sim
Sim result
set Sim = ODTK.Scenario(0).Simulator("Simulator_DOR_QDOR")
startDate = "18 Aug 2020 00:00:00.000"
stopDate = "20 Aug 2020 00:00:00.000"
numDDOR = 3
slewTime = 60.0
interSeqTime = 7000.0
satName = "MMO"
quasarID = 0
quasarDirTolerance = 10.0
ephFile = "C:\MarsSat_Truth.e"
detailsFile = "C:\MarsSat_DOR_Details.txt"
fac1Name = "DSS65"
fac2Name = "DSS34"
satName = "MarsSat"
obsFile = "C:\MarsSat_DOR_QDOR.gobs"
set result = Sim.SimulateDeltaDOR (startDate, stopDate, numDDOR, _
                                   slewTime, interSeqTime, fac1Name, _
                                   fac2Name, satName, quasarID, _
                                   quasarDirTolerance, ephFile, obsFile, _
                                   detailsFile)
msgbox result.succeed
msgbox result.messages
msgbox result.numsequencesgenerated
msgbox result.numtripletsgenerated
msgbox result.numobservationsgenerated

CAgAttr SimulateLandmarkOpNav(const string& startString, const string& stopString, const string& targetBodyString, const string& satelliteString, const string& trackingInstrumentString, const string& scheduleFileName, const string& referenceSimrun, const string& observationFileName, const string& detailsFileName, bool addToScenarioMeasFileList)

Generates simulated Optical Navigation (OpNav) landmark measurements based on a specified reference simulation run (.simrun) to a tracking data file in either generic observation format (.gobs) or OpNav format (.opnav). ODTK can then use the resulting OpNav Landmark Right Ascension and OpNav Landmark Declination measurements for estimation. The simulator uses the following data to complete the measurement generation:

  • Landmark locations from the file identified by the LandmarkFilename setting in the Scenario.CentralBodiesList for the identified target body
  • White noise settings based on the Simulator object setting for inclusion of white noise, applying these to the OpNav Landmark measurement types in the generation of random variations to the computed measurement values
  • Visibility constraints associated with collection of landmark OpNav measurements, such as the minimum elevation angle of the satellite and of the Sun relative to the landmark centroid, from the settings on the specified TrackingInstrument
  • The reference simulation run, which generates a time history of spacecraft and relevant bias states, which the simulator uses during the generation of OpNav Landmark measurements
  • Time-correlated measurement system biases based on the stochastic model definitions in the OpNavCamera setting of the TrackingInstrument, used in the generation of the time history of these biases in the reference simulation run, subject to related ErrorModeling settings in the Simulator, and incorporated during measurement modeling during the generation of OpNav landmark measurments

You can choose to have the landmarks automatically selected or you can specify them via a specially formatted interval file. If you choose auto-selection, the simulator will select the landmark that sees the satellite at the highest elevation angle. If you set the OpNavCamera.CameraPointingMethod to “FixedInSatelliteBodyFrame”, then the simulator will add a constraint that landmarks must be within the field of view of the camera. The message viewer will display the number of measurements written and the number of unique landmarks used.

The TrackingInstrument object must contain the appropriate measurement statistics for the OpNav Landmark Right Ascension and OpNav Landmark Declination measurement types for simulation to be successful.

You can view a sample of an interval file containing a variety of interval description strings including one for specifying a landmark in (1) your install folder at <install_folder>\AGI\STK_ODTK 13\Help\STK\Content\stk\example_intervalList3.htm, and (2) here

Parameters

startString string Enter the time to start generating simulated observations.
stopString string Enter the time to stop generating simulated observations.
targetBodyString string Enter the name of the target central body on which the landmarks are located (e.g., Moon). The simulator will pull landmark locations from the file identified by the LandmarkFilename setting in the Scenario.CentralBodiesList for the identified target body.
satelliteString string Enter the name of the Satellite object hosting the Tracking Instrument that models the OpNav camera.
trackingInstrumentString string Enter the name of the Tracking Instrument that models the OpNav camera.
scheduleFileName string

Enter the fully qualified file name for the interval file containing the observation schedule. You must indicate landmarks on each interval line in the file. Specify the string “AUTO” instead of a file name to indicate to ODTK processing that the simulator should select, at each simulation time step, the landmark that sees the satellite at the highest elevation angle. The argument "maxSimultaneousTargets", which has a default value of 1, controls the number of landmarks for which the simulator generates measurements in AUTO mode.

The simulator ignores the DTSEC keyword since the generation of OpNav landmark measurements is restricted to conform to the time grid created during the reference simulation run.
referenceSimrun string Enter the fully qualified file name for the reference simulation run that establishes the time grid and state history used in the generation of the OpNav landmark measurements.
satelliteString string Enter the name of the output observation file, (.gobs) or (.opnav) format, into which the simulator writes the generated OpNav landmark observations.
observationFileName string (Optional) Enter the path of a text file to which the simulator writes details about the measurement generation. the name of an optional text file to which the simulator writes details about the measurement generation.
detailsFileName string (Optional) Enter the path of a text file to which the simulator writes details about the measurement generation.
addToScenarioMeasFileList bool (Optional) Enter a Boolean indicating if the function should add the generated measurement file to the list of measurement files in the Scenario properties. The default setting is true.
maxSimultaneousTargets integer (Optional) Enter an integer indicating the maximum number of simultaneous targets for which the simulator generates observations when in AUTO select mode. The default setting is 1. You must specify addToScenarioMeasFileList to have the simulator use maxSimultaneousTargets.
overrideVisibilityChecks bool (Optional) Enter a Boolean that, if set to true, will override the result of visibility checks for the generation of measurements when you are using a custom schedule. Using a setting of true places the onus on yourself to make sure that the custom schedule contains valid measurement collection times. The default setting is false.

Return Value

Succeed CAgAttrBool This returns true if successful.
Messages CAgAttrString This provides informational or error messages to display in the status line.
NumObservationsGenerated CAgAttrInt This returns the number of QDOR + DOR observations generated.
NumLandmarksUsed CAgAttrInt This returns the number of Q-S-Q triplets generated. The function converts each triple to one DeltaDOR measurement during estimation.

Example VBS:

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Dim Sim
Dim result
set Sim = ODTK.Scenario(0).Simulator("Simulate_Landmark_OpNav")
startDate = "18 Aug 2024 00:00:00.000"
stopDate = "20 Aug 2024 00:00:00.000"
targetBody = “Moon”
satName = "LunarOrbiter"
trackingInstrument = “OpNavCamera”
scheduleFile = “AUTO”
simrun = Sim.Output.DataArchive.Filename
obsFile = "C:\OpNavCam_Landmark_Observations.gobs"
detailsFile = "C:\OpNavCam_Landmark_Details.txt"

set result = Sim. SimulateLandmarkOpNav (startDate, stopDate, targetBody, _
                                         satName, trackingInstrument, _
                                         scheduleFile, simrun, obsFile, _
                                         detailsFile)

msgbox result.Succeed
msgbox result.Messages
msgbox result.NumObservationsGenerated
msgbox result.NumLandmarksUsed

bool Stop()

Use this to stop the execution of the simulator.

Return Value

bool Always true

Example VBS:

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bSuccess = sc.Simulator(0).Stop