You can configure the Orbit Determination Properties for any GroundAntenna through FreeFlyer script or the Object Browser. There are two ways to navigate to the "Antenna Model" page under the Orbit Determination section of the GroundStation object editor:
1.Open the desired GroundStation's editor and navigate to the Antenna Model page under Orbit Determination
2.Highlight the desired GroundAntenna on the "Objects to Process" page of a Kalman Filter, Square Root Information Filter, Unscented Kalman Filter, or Batch Least Squares object editor and click the "Modify GroundAntenna Estimation Options" button
From this page, you can configure any of these options:
•The GroundAntenna ID, transmitter frequency, and receiver frequency
•The GroundAntenna properties that you want to ignore, estimate, or consider
oIgnore: Leave the property out of the estimated state.
oEstimate: Include the property in the estimated state and allow the estimator to update its value.
oConsider: Include the property in the estimated state, but do NOT allow the estimator to update its value. This means that the property gets included in the covariance, but is not directly estimated.
•The A Priori Bias, Sigma, and Process Noise for each of the properties
Different GroundAntenna properties can be estimated depending on whether you are processing Ground observations, TDRS observations, or BRTS observations.
GroundAntenna OD Properties
To define the GroundAntenna properties that you want to estimate or consider via FreeFlyer script, you will access the GroundAntenna's OD properties, as shown in the example below:
Canberra.Antenna.OD.TimeTagBias.ProcessAction = 0;
Canberra.Antenna.OD.GroundObservation.Range.Bias.ProcessAction = 0;
Canberra.Antenna.OD.GroundObservation.RangeRate.Bias.ProcessAction = 0;
Canberra.Antenna.OD.GroundObservation.Azimuth.Bias.ProcessAction = 0;
Canberra.Antenna.OD.GroundObservation.Elevation.Bias.ProcessAction = 0;
Canberra.Antenna.OD.GroundObservation.RightAscension.Bias.ProcessAction = 0;
Canberra.Antenna.OD.GroundObservation.Declination.Bias.ProcessAction = 0;
Canberra.Antenna.OD.TDRSObservation.OneWayDoppler.Bias.ProcessAction = 0;
Canberra.Antenna.OD.TDRSObservation.TwoWayDoppler.Bias.ProcessAction = 0;
Canberra.Antenna.OD.TDRSObservation.TwoWayRange.Bias.ProcessAction = 0;
Canberra.Antenna.OD.BRTSObservation.RemoteTransponderDelay.ProcessAction = 0;
Canberra.Antenna.OD.BRTSObservation.TwoWayDoppler.Bias.ProcessAction = 0;
Canberra.Antenna.OD.BRTSObservation.TwoWayRange.Bias.ProcessAction = 0;
Once the GroundAntenna has been configured, it can be used as an observing object or object being observed when simulating tracking data or including tracking data in an estimation process.
Ground Antenna Measurement Model
When the observer is a GroundAntenna, you can configure the measurement model (including the noise, maximum, and minimum values) for each of the following measurement types:
oOne Way Doppler
oTwo Way Doppler
oTwo Way Range
oTwo Way Doppler
oTwo Way Range
You can configure these values through the Object Browser by double-clicking on the desired GroundStation and navigating to the "Measurement Model" page under the Orbit Determination section, as shown in the image below:
The GroundStation Measurement Model Editor
You can also configure these options through FreeFlyer script, by accessing various properties of the GroundAntenna object:
// Ground Observation Antenna Properties
Canberra.Antenna.OD.GroundObservation.Range.Noise = 0.02;
Canberra.Antenna.OD.GroundObservation.RangeRate.Noise = 0.0001;
Canberra.Antenna.OD.GroundObservation.Azimuth.Noise = 0.1;
Canberra.Antenna.OD.GroundObservation.Elevation.Noise = 0.1;
Canberra.Antenna.OD.GroundObservation.RightAscension.Noise = 0.1;
Canberra.Antenna.OD.GroundObservation.Declination.Noise = 0.1;
// TDRS Observation Antenna Properties
Canberra.Antenna.OD.TDRSObservation.OneWayDoppler.Noise = 2;
Canberra.Antenna.OD.TDRSObservation.TwoWayDoppler.Noise = 2;
Canberra.Antenna.OD.TDRSObservation.TwoWayRange.Noise = 0.005;
// BRTS Observation Antenna Properties
Canberra.Antenna.OD.BRTSObservation.TwoWayDoppler.Noise = 2;
Canberra.Antenna.OD.BRTSObservation.TwoWayRange.Noise = 0.005;
You can also configure the troposphere model used for each GroundAntenna by specifying the Mean Surface Refractivity based on each month of the year. This is used for determining tropospheric time/range bias. The monthly refractivity can thus be configured to set different tropospheric correction values for simulating measurements vs. when processing.
You can configure these values through the Object Browser by double-clicking on the desired GroundStation and navigating to the "Troposphere Model" page under the Orbit Determination section, as shown in the image below, or through FreeFlyer script.
The GroundStation Troposphere Model Editor