With a satellite, facility, or GPS Satellite highlighted in the Object Browser, click the button or select Transponder from the Object Catalog to attach a transponder to the satellite. The following properties can be specified for a transponder:
|Type||Defines the type of ranging signals received and retransmitted
by the transponder. Choices are:
NOTE: A satellite can have multiple transponders to model the use of multiple ranging paths used in the tracking of the satellite. Each transponder can have its own constant bias and state estimate. In most cases, transponders are limited to one of each type. However multiple Relay transponders are allowed to support TDRS, and multiple SatToGround transponders are allowed to support Range and Doppler.
|TransponderID||Enter an integer representing a unique identification number for this transponder. See the special note below related to transponder ids on TDRS spacecraft.|
|EstimateBias||A correction to the constant transponder bias will be estimated by the filter if set to true and two-way range measurements are processed. Also controls whether transponder bias can be varied by the Simulator.|
Select TimeUnits or DistanceUnits and then set the BiasModel.
Choices for the BiasModel include:
|RFInfo||Information related to relay transponder selection and use.
Currently only used during the processing of TDOA and FDOA
|DefaultAntenna||If the transponder is attached to a satellite, to which one or more antennas are also attached, the name of each of those antennas will appear in a dropdown list. Select the antenna that you wish to designate as the default antenna for the transponder. The default antenna is always used for the simulation of measurements and for the processing of measurements when an antenna is not specified by the tracking data. If no default antenna is specified and no antenna is specified in the tracking data then no antenna processing will be applied in either the simulation or processing of measurements.|
|DefaultAntenna2||Available only if Type (above) = Relay. In the case of relay transponders, the first antenna is designated to be the ground link antenna while the second antenna is the space link antenna. Selection works the same way as for DefaultAntenna.|
Note: Specific transponder paths are identified in UTDF formatted tracking data for TDRS spacecraft. In order to model the commonly used signal paths properly during the processing of 4L Range and 4L BRTS Range observations, each TDRS satellite should be configured with eight transponders with the following transponder ids:
SA1 - SA1 = 11
SA2 - SA2 = 22
MA - MA - 1 = 331
MA - MA - 2 = 332
MA - MA - 3 = 333
MA - MA - 4 = 334
MA - MA - 5 = 335
MA - MA - 6 = 336
where the transponder ids are constructed from a combination of the forward path and the return path where: 1 corresponds to SA1, 2 corresponds to SA2 and 3 corresponds to MA. The final digit in the MA ids above reflects the fact that there are 6 separate transponder paths using the MA service. In all cases shown here, the forward and return paths are the same.