Communications System
The Communications System page enables you to define any number of communications systems via the frequency band and the system type such as receiver, transmitter, or both. The communication systems can also be linked to sensor objects on the satellite. This provides you with the ability to enable pulsing on the selected STK object when the transmitter is powered.
Properties
Clicking on a particular communications system in the Communications Systems list activates the modeling attributes for that system. Each system contains the following common attributes:
| Parameter/Control | Description |
|---|---|
| Name | Name of the communications system |
| Link to STK satellite object | Associates the payload to a sensor object on the STK satellite. |
| Receiver | If selected, indicates that there is a receiver part to the communications system. When selected, the receiver tab is available. |
| Transmitter | If selected, indicates that there is a transmitter part to the communications system. When selected, the transmitter tab is available. |
The type of system you choose dictates what other parameters are available.
Receiver
| Parameter/Control | Description | Units |
|---|---|---|
| Data Rate | Data rate for the receiver | User-Specified |
| Overhead | Percentage of overhead subtracted from the data rate; used to simulate packet / framing overhead | % |
| Power Consumption | Power consumption of the receiver when in the "On" state | W |
| Standby Power | Power consumption of the receiver when in the "Standby" state | W |
Transmitter
| Parameter/Control | Description | Units |
|---|---|---|
| Data Rate | Data rate for the transmitter | User-Specified |
| Overhead | Percentage of overhead subtracted from the data rate; used to simulate packet / framing overhead | % |
| Power Consumption | Power consumption of the transmitter when in the On state | W |
| Standby Power | Power consumption of the transmitter when in the Standby state | W |
Antenna
| Parameter/Control | Description | Units |
|---|---|---|
| Omni-Directional | If selected, indicates that the antenna is not directional | N/A |
| Boresight | Pointing direction unit vector for the antenna | N/A |
| Field-of-View | Half angle field-of-view for the antenna | deg |
Modeling
Data rate units
Communication data rates are expressed in multiples of bits per second (bit/sec). To convert between these units, use the binary system, for example, 1 Gbit/sec translates to 230 bit/sec, 220 kbit/sec, and 210 Mbit/sec.
Power
Receivers and transmitters have three possible states: Off, On, and Standby. These states determine the power consumed by the comm system based on user-specified values. A system in the Off state will always consume no power. To include the power consumption of the comm systems, ensure Communications Power is selected in the Add Variable Loads section of the Power tab on the Power/Thermal page.
Data
The receiver model can be used to form a coarse understanding of sending data to the spacecraft. Data received via this method does not add to the state of the data recorder.
The transmitter model is connected to the data recorder and will reduce the amount of data in the recorder based on the specified data rate and overhead. For example, a 10 Mbps transmitter with 10% overhead will reduce the data in the recorder by 9 Mbps.