Operational and Performance Aspects of a Turn-Around Tracking System

Abstract

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.

Performance Assessment of a Turn Around Ranging in Communication Satellite Orbit Determination

“…Measat operational experience shows that TAR orbit determination accuracy is similar to classical ranging station performance. TAR makes ground station operations simplified [1].…”

“…Technical properties and utilization type of the station influence orbit estimation accuracy. Satellite operators prefer reliable, highperformance, and cost-effective station solutions [1], [2].…”

“…Single station tracking is the most frequently used ground station system for orbit determination of a communication satellite. Satellite operators alternatively select other types of tracking systems, such as turn around range measurement or four-way range measurement systems for NSSK and EWSK operations [13]. When selecting a system, the satellite operator's target is to improve orbit determination accuracy and decrease the system's operational complexity and cost.…”

Determination of the Ground Station Locations for both Dual-Site Ranging and Site-Diversity at Q/V-band Satellite Communication for an Intersatellite System Scenario

“…One of them is to use a single antenna, with azimuth, elevation and range between the antenna and the GEO satellite information. Another method is to use multiple antennas by 2-way or 4-way range information between two physically separated antennas to the GEO satellite that is named as TAR [12,14]. If the ranging measurements have better accuracy, the angle (azimuth, elevation) information of the antennas are of secondary importance as they are relatively less accurate compared to the ranging [12].…”