The RangingMethod attribute may apply to a satellite based tracking insturment or facility object. In the case of a satellite based tracking instrument, the ranging method is applied to space based tracking where one satellite produces measurements of another satellite. Ranging method options reflect the difference between cooperative and surveillance tracking.
Currently only one constant ranging bias/delay value can be applied to the ranging model. In the case of facility, RangingMethod selects whether the transponder bias, the retroreflector delay, or neither (skin-track), is applied to the modeled range from that facility. The RangingMethod is used when processing Range-type measurements to determine whether to apply and estimate the transponder bias, the retroreflector bias, or neither. Note that when processing NP Range, which is the normal point laser range type, the ranging method is ignored and by default any available retroreflector biases are applied and allowed to be estimated (if the retroreflector object is configured to estimate bias).
| Ranging Method Options | ||
|---|---|---|
| Option | Tracking Type | Description |
| Transponder | Cooperative (Active) |
Indicates a tracking station such as SGLS that generates tracking data only through an active transponder on the spacecraft. For this option a transponder bias can be assigned as a filter state, and the transponder bias estimate is used in the range and Doppler measurement models. |
| Retroreflector | Cooperative (Passive) |
Indicates a ground-based tracking facility, such as an ILRS station, that generates tracking data only through a passive retroreflector on a spacecraft. A retroreflector delay can be assigned as a filter state, and the retroreflector delay estimate is used in the range measurement models. |
| SkinTrack | Surveillance | Indicates a surveillance tracking station, either radar or optical, that does not actively use the satellite transponder or retroreflector (e.g. in surveillance of enemy satellites). For this option, the transponder or retroreflector delay is not used in the range and Doppler measurements. |