Tropospheric Scintillation Models

ITU-R P618-8 Model

This ITU Tropospheric Scintillation model is included for backward compatibility and is superseded by ITU-R P618-12.

Parameter	Description
Surface Temperature	Enter the surface temperature value.
Tropo Fade Outage	Enter the Tropospheric Fade Outage as a percentage. STK computes the loss in dB that occurs for the percentage time not exceeding the specified limit.
Percent Time Refractivity Gradient < -100 N units/km	The percentage of time that the reflectivity gradient in the lowest 100 meters of the atmosphere is less than -100 N units/km.

As of STK 12.7, the model decides whether to calculate deep fade or shallow fade depending on the link elevation angle. In previous versions of STK, you could select a Compute Deep Fade check box to force a deep fade calculation. For older scenarios with this check box selected, STK 12.7 and later will ignore this selection.