An STK Communications receiver models output as follows:
The received Doppler shifted frequency is:
where:
fIn is the transmitted frequency
c is the speed of light
is the relative velocity between the transmitter and receiver
The received isotropic power and flux density are calculated using:
where:
EIRP is the transmitter EIRP
c is the speed of light
Lprop is the total propagation losses between the transmitter and receiver
f is the received frequency
The manner in which receiver g/T is handled differs depending on the type and model of receiver. Radar receivers are equivalent to complex Comm receivers for this purpose.
Receiver g/T output
| Type and Model | Manner in Which g/T is Handled |
|---|---|
| Comm - Simple | User input. |
| Comm - Medium | Gain is user input, with an option to calculate system temperature. |
| Comm - Complex Radar |
Gain and system temperature can be calculated. |
For radars and complex receivers, the Sun and Earth antenna temperatures are calculated by integrating the antenna pattern over the noise source. For medium receivers, the full noise source temperature is produced by determining if the receiver loss intersects the noise source disk.