RunEstimator — Ingests navigation measurements and generates an estimated state vector
The RunEstimator command ingests navigation measurements and generates an estimated state vector according to the specifications of the input BatchEstimatorInv resource.
See Also: BatchEstimatorInv
How GMAT generates “Computed (C)” DSN data
As part of the estimation process, GMAT must calculate the so-called observation residual, “O-C,” where “C” is the “Computed” measurement. As discussed in the RunSimulator help, GMAT calculates the DSN range “C” measurement as
and GMAT calculates the DSN Doppler measurement as
The value of C and M2 used to calculate the computed range or Doppler measurement depends upon the data type and whether the data being ingested is ramped or non-ramped according to the table below. The value of the transmit frequency used to calculate the computed measurement depends upon whether or not the data being ingested is ramped or non-ramped.
|Data Type||Value of C (Range) or M2 (Doppler) used to calculate “Computed” measurement||Value of transmit frequency used to calculate “Computed” measurement|
|Estimate Range without ramp table||
|Estimate Range with ramp table||
|Estimate Doppler without ramp table||
|Estimate Doppler with ramp table||
Earth Nutation Update Interval
If you want the estimator to calculate a Doppler or range rate type of measurement (e.g., DSN_TCP and RangeRate) residual precisely, you will need to set the Earth nutation update interval to 0 as shown below.
Earth.NutationUpdateInterval = 0
It is good general practice to set the Earth nutation update interval to zero for all measurement types.
Run batch estimator.
Create BatchEstimatorInv myBatchEstimator BeginMissionSequence RunEstimator myBatchEstimator
For a comprehensive example of reading in measurements and running the estimator, see the Chapter 14, Orbit Estimation using DSN Range and Doppler Data tutorial.