Defining Measurement Model

The Measurement model configuration necessary for your Orbit Determination system depends on the type of Observations you are working with. For each Observation type, different observing objects or objects being observed will be used, as discussed on the Simulating Tracking Data page. The objects used by each Observation type, as well as the object properties that will affect the Observation, are shown in the table below.

Follow the links to each object type to learn more about how to edit the properties used by each Observation.

Observation Type	Objects Used	Corrections Used - Biases	Measurement Noise
BRTS Observations	GroundAntenna	Two-way Range Bias Two-way Doppler Bias TimeTag Bias	Two-way Range Noise Two-way Doppler Noise
BRTS Observations	TDRSTransponder	Transponder Delay	None
Custom Observations	User-Specified	User-Specified	User-Specified
DSN Observations	GroundStation	Latitude Bias Longitude Bias Height Bias	None
	GroundAntenna[2]	Range Bias Range Rate Bias TimeTag Bias	Range Noise Range Rate Noise
	Transponder (Optional)	Transponder Delay	None
GNSS Observations	GNSSReceiver	Clock Bias Clock Drift GalileoInterSystemBias	Receiver Noise
Ground Station Observations[1]	GroundStation	Latitude Bias Longitude Bias Height Bias	None
	GroundAntenna	Range Bias Range Rate Bias Azimuth Bias Elevation Bias Right Ascension Bias Declination Bias TimeTag Bias	Range Noise Range Rate Noise Azimuth Noise Elevation Noise Right Ascension Noise Declination Noise
	Transponder (optional)	Transponder Delay	None
Point Solution Observations	GNSSReceiver	TimeTag Bias X Bias Y Bias Z Bias VX Bias VY Bias VZ Bias	X Noise Y Noise Z Noise VX Noise VY Noise VZ Noise
Spacecraft Observations	Sensor	Range Bias Range Rate Bias Azimuth Bias Elevation Bias Right Ascension Bias Declination Bias TimeTag Bias	Range Noise Range Rate Noise Azimuth Noise Elevation Noise Right Ascension Noise Declination Noise
Spacecraft Observations	Transponder (optional)	Transponder Delay	None
TDRS Observations	GroundStation	Latitude Bias Longitude Bias Height Bias	None
	GroundAntenna	Two-way Range Bias Two-way Doppler Bias One-way Doppler Bias TimeTag Bias	Two-way Range Noise Two-way Doppler Noise One-way Doppler Noise
	TDRSTransponder	Transponder Delay	None
	Transponder (optional)	Transponder Delay	None

[2] Note: DSN observations are derived from Ground Station observations, and therefore have all the same biases and measurement noise options available. Because of the long range nature of DSN observations, angular data is not generally very informative, so Azimuth, Elevation, Right Ascension, and Declination measurements are not used by default, and therefore their associated biases/noises are not included in this table.