Results obtained using operational four-way TAR data are analyzed and compared to results obtained with both 2-station range measurements and 1-station range and angle measurements. Four-way turn around ranging (TAR) is currently in use operationally by Measat for their new satellite, M-3a (formerly M-1R). The orbital accuracies being obtained for the TAR are similar to ones obtained using classical 2-station ranging when the same two stations used for the TAR are compared. TAR does not make the satellite operations more complex however there are slightly different calibrations that need to be performed. Several cases are considered, including free space propagation and maneuver estimation, both with solar radiation pressure scale factor estimation. The test cases were analyzed using GMV's focusGEO software. The tracking scenario using the full set of tracking measurement including TAR, range, and angles yields the baseline for orbital accuracies used for comparison to the other TAR scenarios. The TAR only orbit determination produces an orbit determination that is on par with the full measurement set solution as does the TAR plus range case. Therefore the use of TAR measurements in place of more costly scenarios is a viable option for GEO satellites. The test case demonstrate focusGEO's ability to consistently mix tracking data types while estimating dynamic parameters and produce a reliable orbit determination solution from TAR measurements independent of the ground stations producing the raw measurements.

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