Starting in STK 9, the Comm Connect commands, including Environment, were enhanced to make use of attributes and to simplify the format required to use these commands. The Environment Connect commands now enable you to get and set attribute values using the following formats:
To get attribute values and information from the scenario's RF Environment properties:
Environment_RM <ScenarioPath> GetValue [<AttributePath>]
To set attribute values for the scenario's RF Environment:
Environment <ScenarioPath> SetValue <AttributePath> <Value> [<Unit>]
The new Comm Connect commands use an attribute path to identify the location - within the RF Environment properties - of the targeted attribute. The exact syntax and length of the attribute path depends upon the individual attribute. Each part of the attribute path must be separated by a period (.), including the attribute itself.
Further descriptions of the command syntax can be found here: Environment and Environment_RM.
Related Commands
The following command examples show how to switch over to the new Environment command format from the old STK 8 format.
Example 1
To use the ITU-R P.618-5 rain model in calculations, set the surface temperature (in degC) and the rain outage (in %).
In STK 8, use the Environment command:
Environment * RainModel On ITU_P618_5 28.6
Environment * RainOutage 0.03
In STK 9 or later, you can first use the Environment_RM GetValue command to get the names and current settings of the RF Environment's attributes. Numeric values are displayed in internal units. "Read-only" attributes can not be changed.
Environment_RM * GetValue
UserComment = STK RF Environment
PropagationChannel = RF_Propagation_Channel
PropagationChannel.UserComment = RF Propagation Channel
PropagationChannel.UseCloudFogModel = false
PropagationChannel.CloudFogModel = ITU_840-3 (Read-only)
PropagationChannel.CloudFogModel.UserComment = ITU 840-3 (Read-only)
PropagationChannel.CloudFogModel.CloudCeiling = 3000.00000000 m (Read-only)
PropagationChannel.CloudFogModel.CloudLayerThickness = 500.00000000 m (Read-only)
PropagationChannel.CloudFogModel.CloudTemp = 273.15000000 K (Read-only)
PropagationChannel.CloudFogModel.CloudLiqWaterDensity = 7.50000000 g*m^-3 (Read-only)
PropagationChannel.UseTropoScintModel = false
PropagationChannel.TropoScintModel = ITU_618-8_Scintillation (Read-only)
PropagationChannel.TropoScintModel.UserComment = ITU 618-8 Scintillation (Read-only)
PropagationChannel.TropoScintModel.ComputeDeepFade = false (Read-only)
PropagationChannel.TropoScintModel.FadeOutage = 0.00100000 unitValue (Read-only)
PropagationChannel.TropoScintModel.PercentTimeRefracGrad = 0.10000000 unitValue (Read-only)
PropagationChannel.TropoScintModel.SurfaceTemperature = 273.15000000 K (Read-only)
PropagationChannel.UseRainModel = false
PropagationChannel.RainModel = ITU-R_P618-10 (Read-only)
PropagationChannel.RainModel.UserComment = ITU-R P618-10 rain model (Read-only)
PropagationChannel.RainModel.SurfaceTemperature = 273.15000000 K (Read-only)
PropagationChannel.UseAtmosAbsorptionModel = false
PropagationChannel.AtmosAbsorptionModel = Simple_Satcom (Read-only)
PropagationChannel.AtmosAbsorptionModel.UserComment = Simple Satcom gaseous absorption model (Read-only)
PropagationChannel.AtmosAbsorptionModel.SurfaceTemperature = 293.15000000 K (Read-only)
PropagationChannel.AtmosAbsorptionModel.WaterVaporConcentration = 7.50000000 g*m^-3 (Read-only)
PropagationChannel.UseUrbanTerresPropLossModel = false
PropagationChannel.UrbanTerresPropLossModel = Two_Ray (Read-only)
PropagationChannel.UrbanTerresPropLossModel.UserComment = Two Ray (Fourth Power Law) atmospheric absorption model (Read-only)
PropagationChannel.UrbanTerresPropLossModel.SurfaceTemperature = 273.15000000 K (Read-only)
PropagationChannel.UrbanTerresPropLossModel.LossFactor = 1.000000 (Read-only)
PropagationChannel.UseCustomA = false
PropagationChannel.CustomA = Script_Plugin (Read-only)
PropagationChannel.CustomA.UserComment = Atmospheric model script plugin (Read-only)
PropagationChannel.CustomA.AtmosAbsorpScriptFile = <empty> (Read-only)
PropagationChannel.UseCustomB = false
PropagationChannel.CustomB = Script_Plugin (Read-only)
PropagationChannel.CustomB.UserComment = Atmospheric model script plugin (Read-only)
PropagationChannel.CustomB.AtmosAbsorpScriptFile = <empty> (Read-only)
PropagationChannel.UseCustomC = false
PropagationChannel.CustomC = Script_Plugin (Read-only)
PropagationChannel.CustomC.UserComment = Atmospheric model script plugin (Read-only)
PropagationChannel.CustomC.AtmosAbsorpScriptFile = <empty> (Read-only)
EarthTemperature = 290.00000000 K
RainOutagePercent = 0.100000
ActiveCommSystem = None
Use the Environment SetValue command to enable use of the rain model, select a model type, and define surface temperature and rain outage attributes:
Environment * SetValue PropagationChannel.UseRainModel true
Environment * SetValue PropagationChannel.RainModel ITU-R_P618-5
Environment * SetValue PropagationChannel.RainModel.SurfaceTemperature 28.6 degC
Environment * SetValue RainOutagePercent 0.03
Example 2
To use the ITU-R P.676-5 atmospheric absorption model in calculations.
In STK 8, use the Environment command to enable the absorption model, select a model type, and use the fast approximation method but not the season and latitude-dependent model:
Environment * Absorption On "ITU-R P.676-5" UseFastOn UseSeasonOff
In STK 9 or later, first use the Environment_RM GetValue command to get the Choices for Absorption model:
Environment_RM * GetValue PropagationChannel.AtmosAbsorptionModel:Choices
ITU-R_P676-5
Script_Plugin
Simple_Satcom
TIREM_3.31
ITU-R_P676-3
TIREM_3.10
TIREM_3.16
TIREM_3.20
Set the RF Enviroment Atmospheric Absorption Model and attributes:
Environment * SetValue PropagationChannel.UseAtmosAbsorptionModel true
Environment * SetValue PropagationChannel.AtmosAbsorptionModel ITU-R_P676-5
Environment * SetValue PropagationChannel.AtmosAbsorptionModel.UseApproxMethod true
Environment * SetValue PropagationChannel.AtmosAbsorptionModel.UseSeasonalRegional false
Example 3
To turn on computing of cloud and fog fade, set the cloud ceiling to 8000 m, and set the cloud liquid water density to 1.25e7 kg/km^3:
In STK 8, use the Environment command:
Environment * CloudFog Compute On Ceiling 8000.0 Density 1.25e7
In STK 9 or later, use the Environment SetValue command:
Environment * SetValue PropagationChannel.UseCloudFogModel true
Environment * SetValue PropagationChannel.CloudFogModel.CloudCeiling 8.0 km
Environment * SetValue PropagationChannel.CloudFogModel.CloudLiqWaterDensity 12.5 g/m^3
Use the Environment_RM GetValue command to view the result:
Environment_RM * GetValue PropagationChannel.CloudFogModel
PropagationChannel.CloudFogModel = ITU_840-3
PropagationChannel.CloudFogModel.UserComment = ITU 840-3
PropagationChannel.CloudFogModel.CloudCeiling = 8000.00000000 m
PropagationChannel.CloudFogModel.CloudLayerThickness = 500.00000000 m
PropagationChannel.CloudFogModel.CloudTemp = 273.15000000 K
PropagationChannel.CloudFogModel.CloudLiqWaterDensity = 12.50000000 g*m^-3
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