Environment Model Prioritization

In STK, you can set RF and Laser Environment propagation model types (rain, tropospheric scintillation, etc.) at all three levels: scenario, platform (facilities, places, targets, and all vehicles except satellites), and sub-object (transmitter, receiver, radar, and antenna). This topic explains the priority ordering that STK uses to delineate which model selections take precedence when you enable more than one of the same model type on different levels and objects. For example, if you enable the ITU-R P676-9 atmospheric absorption model on the scenario properties and the VOACAP atmospheric absorption model on a receiver, STK will use the VOACAP model for all communication links with that receiver.

The following prioritization goes from highest to lowest.

  1. Receive-side communication or radar object – If you enable a propagation model on the receive side communication or radar object, STK will use that model as a factor in the total propagation loss. The receive-side object could be a receiver or a radar.
  2. Receive-side linked antenna object – This only applies to receiver and radar models that allow linking to the antenna object. For instance, in Communications, the Complex Receiver model allows you to link to an antenna object. If you do not enable the propagation model on the receiver itself but enable it on the antenna object, STK will use the antenna object's propagation model to factor into the total propagation loss.
  3. Transmit-side communication or radar object – Model selection at this level takes precedence if you enable the propagation model on the transmit-side communications or radar object and do not enable a model on the receive-side object (or linked antenna object, if applicable). STK will then use this model to factor into the total propagation loss of the link.
  4. Transmit-side linked antenna object – This only applies to transmitter and radar models that allow linking to the antenna object. For instance, in Communications, the Complex Transmitter model allows you to link to an antenna object. If you do not enable the propagation model on the receive-side nor on the transmitter itself but enable it on the transmitter antenna object, STK will use the antenna object's propagation model to factor into the total propagation loss.
  5. Receive-side parent platform object – If you do not enable the propagation model on either the transmit or receive side of the link at the sub-object level, then STK will use the receive-side parent-platform propagation model to factor into the total propagation loss.
  6. Transmit-side parent platform object – This applies when you do not enable the propagation model on either the transmit or receive side of the link at the sub-object level, and you do not enable the model on the receive platform. STK will then use the transmit-side parent-platform propagation model to factor into the total propagation loss.
  7. Scenario – This applies when you do not enable the propagation model on either the receive or transmit side of the link, both at the sub-object and platform levels. If you enable the model for the scenario, STK will use that model to factor into the total propagation loss.