Setting up an OD System

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FreeFlyer contains several different objects that have at least one property that can be estimated. For information on the configuration of these objects, see:


Spacecraft OD Setup

oGNSSReceiver Setup

oSensor Setup

oTransponder Setup

oTDRSTransponder Setup

GroundStation OD Setup

oGroundAntenna Setup

Thrust Event OD Setup

oImpulsiveBurn Setup

oFiniteBurn Setup

oOutgassingEvent Setup


The estimator forms the core of any OD process. It contains references to the objects to be estimated (as listed above) as well as references to all tracking data to be processed. FreeFlyer supports four kinds of estimators: Extended Kalman Filter, Square Root Information Filter, Unscented Kalman Filter, and Batch Least Squares. For more information, see:


Estimation Techniques

oSetting up a Batch Least Squares Estimator

oSetting up an Extended Kalman Filter

oSetting up a Square Root Information Filter

oSetting up an Unscented Kalman Filter

oSetting up a Smoother


After choosing your estimation technique, there are a few other areas that require some configuration. Additional items that you may need to set up include:


Defining A Priori States

Defining Measurement Model

Defining Thrust Events

Defining Properties to Estimate

Including Tracking Data in an Estimation Process


Once you have completed the initial setup of your OD system, continue to the Tracking Data and Performing State Estimation sections for information on how to use your configuration to generate results.