Description
A GroundStation is a tracking station used for determining line of sight contact with a Spacecraft. GroundStation Objects can be placed on any built-in or custom Celestial Body Objects. It is used to compute contact duration, antenna pointing, acquisition of signal (AOS), and loss of signal (LOS) information with a Spacecraft. See the Coverage and Contact Analysis guide for more information. You can assign GroundStation objects using the = operator. This will equalize the GroundStations' properties, but not the properties of the attached GroundAntenna objects.
Inheritance Hierarchy: ObjectàGroundStation
Available In Editions:
Engineer
Mission
Timing Precision Mode
This page describes functionality in millisecond timing precision mode.
Name
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Description
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Antenna
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The Antenna property is used to define the characteristics of tracking data being provided from the ground station. See the Orbit Determination Guide for more information.
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CentralBody
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The name of the CelestialObject on which the GroundStation is located.
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CentralBodyObject
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The CelestialObject on which the GroundStation is located.
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Color
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The color of the GroundStation when visualized in a Mission View. The color can be overridden for an individual view using the ViewWindow.SetObjectColor() method.
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ConeElevation
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If the MaskShape value is set to 'Cone', this property defines the constant elevation horizon of the groundstation. When MaskShape is 'None' or 'Points', this property is ignored for calculations, but is used for representing the groundstation in the Mission View.
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DeclaredName
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The name of the object as declared.
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DrawMethod
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Determines how the GroundStation will be rendered in a Mission View. The draw method can be overridden for an individual view using ViewWindow.SetGroundStationDrawMethod() method.
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FixedPosition
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Reports the object's position components (X, Y, Z) referenced to the Body Fixed coordinate system of its central body.
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GeodeticsFilename
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The GroundStation geodetic data file name. The Geodetics file is used for GroundStations with Earth as their central body.
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Height
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The height of the ground station above the reference ellipsoid. The Earth uses the WGS 84 (World Geodetic System 1984) reference ellipsoid.
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InterpolationMode
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The Method used to interpolate between defined points of the groundstation mask when the MaskShape is 'points'.
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Latitude
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The planetodetic latitude of the ground station measured from the equator.
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LHCPolarizationSupport
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This is a customer requested property. It has no effect on simulation. It is merely a value holder.
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LINPolarizationSupport
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This is a customer requested property. It has no effect on simulation. It is merely a value holder.
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Longitude
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The longitude of the ground station east of the prime meridian.
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MaskAzimuth
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When MaskShape is set to 'Points', the MaskAzimuth value for each of the 'n' points can be set. The array index (i.e., 'n') starts at 0 and goes up to NumberOfPoints - 1.
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MaskElevation
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When MaskShape is set to 'Points', the MaskElevation value for each of the 'n' points can be set. The array index (i.e., 'n') starts at 0 and goes up to NumberOfPoints - 1.
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MaskShape
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The type of horizon mask for the ground station. The mask can be defined as a cone, as a series of azimuth and elevation angles, or you can select not to use a mask, in which case the GroundStation can "see" to the horizon.
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MonthlyRefractivity
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Mean Surface Refractivity (N) based on month of year. These values are used in the 'RC (tick Refraction Correction) model. This refraction setting is only used to determine the tropospheric time/range bias in the Orbit Determination system. Tropospheric corrections are only applied when the Earth is the central body for the GroundStation. This refraction setting is not applied when computing any other contact or visibility methods.
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Name
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The name displayed for this object in output windows such as views, plots, and reports.
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NumberOfPoints
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When MaskShape is set to 'Points', this property defines the number points that comprise the masking profile.
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ObjectId
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The unique identifier for the object.
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ObjectType
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The type of the object.
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OD
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This property contains the OD settings for all the GroundStation properties that can be estimated.
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Opacity
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The opacity of the GroundStation when visualized in a Mission View. This does not apply to the GroundStation outline.The opacity can be overridden for an individual view using ViewWindow.SetObjectOpacity() method.
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ReceiverGainTemperature
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The receiver gain temperature.
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RefractionModelType
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Refraction model to use. Refraction can only be computed when the Earth is the central body of the GroundStation. The selected refraction model will be used to compute refracted elevation from this GroundStation, affecting the following methods: GroundStation.ElevationR, GroundStation.CommZAspectAngle, GroundStation.TrackingInterference, Spacecraft.Contact, Spacecraft.ContactTimes, and Spacecraft.PassData. The following refraction models are available:
- None.
- Analytic - Chapman. This Earth refraction model is based on analytic Chapman theory.
- Analytic - Interpolation Table. This model is the same as the VisibilitySegment "Analytic - TRORD" model. This Earth refraction model is based on the TRORD refraction model documented in the "Software Requirements Specification for Tracking and Orbit Determination (TRORD) CPCI 202 of the Command and Control Segment Math Appendix", September 1992. This is a troposphere-only refraction model; ionospheric refraction is not modeled. This model uses the local-mean coefficients for each month specified by the GroundStation.RefractivityNs property.
To access additional refraction models, visibility methods, and observer/target object types, use the VisibilityCalculator and VisibilitySegment objects.
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RefractivityNs
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Local-mean coefficients for each month used with the analytic interpolation table refraction model. If the GroundStation.RefractionModelType is set to "Analytic - Interpolation Table", this array of refraction coefficients is used to compute the refracted elevation from this GroundStation, affecting the following methods: GroundStation.ElevationR, GroundStation.CommZAspectAngle, GroundStation.TrackingInterference, Spacecraft.Contact, Spacecraft.ContactTimes, and Spacecraft.PassData. These refraction coefficients are also used with the VisibilityCalculator and VisibilitySegment objects if this GroundStation is the observer for a Segment and the Segment.RefractionModelType is set to "Analytic - TRORD".
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RHCPolarizationSupport
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This is a customer requested property. It has no effect on simulation. It is merely a value holder.
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SgfStation
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An acronym that corresponds to a station in the Station Geodetics file. This property should contain an alpha/numeric string of four characters. The Geodetics file is used for GroundStations with Earth as their central body.
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TrackingStationId
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A numeric ID which matches the ID within tracking data file(s) associated with this ground station. Note: This property is used in association with Orbit Determination.
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TransmitterEIRP
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The transmitter EIRP.
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Name
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Description
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Azimuth
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Returns the azimuth angle of the argument as seen from the reference object. The definition of azimuth depends on the reference object and the passed arguments.
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CelestialObjectWidth
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Returns the angular width of the provided CelestialObject as observed from the GroundStation position.
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ClearSavedStates
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Clears previous saved states for this object.
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Elevation
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Returns the elevation angle of the argument as seen from the reference object.
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ElevationR
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Returns the elevation angle of the argument as seen from the reference object.
The ElevationR method will account for refraction if refraction modeling is turned on using the GroundStation.RefractionModelType property; otherwise the values returned by the ElevationR method will equal those returned by the Elevation method.
To access additional refraction models, visibility methods, and observer/target object types, use the VisibilityCalculator and VisibilitySegment objects.
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FixedVectorToObject
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Returns an Array containing the components of the vector originating at the location of the prefix object and terminating at the location of the argument object, in the body fixed coordinate frame of the prefix object.
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GetElevationAtAzimuth
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Returns the elevation of the ground station mask at the specified azimuth.
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GetFromFile
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Load the object state from the specified FreeFlyer object file.
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GetFromString
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Load the object state from the specified string.
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GetHeight
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Returns the bodydetic height. Objects below the surface will return a negative height.
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GetPositionAtEpoch
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Reports the GroundStation's position components (X, Y, Z) at the specified epoch in the Mean J2000 Earth Equator frame.
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InShadow
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Returns an integer value indicating whether the GroundStation is in shadow. A value of 1 is returned when the GroundStation is in shadow, and a 0 is returned if it is not. If the GroundStation is below the surface, it will be treated as if it is on the surface.
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LoadFromStationGeodeticsFile
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Loads a GroundStation configuration from a station geodetics file.
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PutToFile
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Convert the object state to FreeFlyer object xml and write to a file.
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PutToString
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Convert the object state to FreeFlyer object xml and return as a string.
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Range
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Returns the distance between two Vehicles, a Vehicle and a GroundStation, or a Vehicle and a CelestialObject. The Range method requires a single argument, either a Vehicle, a CelestialObject, a CelestialObject BodyID, or a GroundStation object.
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RangeRate
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Returns the time rate of change of a Spacecraft's range from either a GroundStation or another Spacecraft.
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ReferenceEquals
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Returns 1 if the argument refers to the calling object and 0 otherwise.
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ResetMethodStates
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Resets any method states associated with the calling object.
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Restore
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Restore an object's state from a previously saved state.
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Save
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Save the object's state so that it can be restored later.
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SetCentralBody
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Sets the body of the calling object.
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SetFixedPosition
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Sets the object's position components (X, Y, Z) referenced to the Body Fixed coordinate system of its central body.
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SetHeight
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Set the object's height.
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TrackingInterference
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Provides detailed information on the times when a GroundStation tracking a Spacecraft is interfered with by a Star, Celestial Object, or another Spacecraft. Interference occurs when the tracked Spacecraft is visible to the GroundStation, but an interfering object(s) lies within a user-specified cone about the GroundStation-to-Spacecraft vector.
FreeFlyer calculates interference based on the times when the center of the interfering object is within the cone. If you want to model a non-zero angular width for an interfering object, you can add half the angular width of that object (as seen from the GroundStation) to the desired interference half-angle to get the total cone half-angle.
Note: When more than one interfering object is specified, ALL of these objects (as opposed to ANY) must lie within the interference cone for the tracking to be considered interfered.
The TrackingInterference method will account for refraction if refraction modeling is turned on using the GroundStation.RefractionModelType property.
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VectorToObject
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Returns an Array containing the components of the vector originating at the location of the prefix object and terminating at the location of the argument object, in MJ2000 Earth Equator coordinates.
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Name
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Description
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StationType
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The type of groundstation.
This property has been Deprecated. This property is part of the legacy Orbit Determination architecture, which is maintained only for backwards compatibility for some operational customers. Please use the new Orbit Determination architecture instead. See the Help File Guide on Orbit Determination for more information.
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See also
Coverage and Contact Analysis Guide
GroundStations Guide
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