Datalinks

Datalinks represent the RF or optical equipment and antenna to downlink data to Earth, directly from satellite to a ground station or via a Data Relay Satellite. Each satellite can be modelled with several data links.

The definition of datalinks is optional. If no datalinks are defined SaVoir will still be able to calculate timelines of satellite to antenna and satellite to satellite visibility contacts, based on simple geometrical visibility contact without consideration of horizon masks or link type.

A datalink has the following properties:

Bit rate: The throughput bit rate of the datalink , used to estimate the duration of downlink data dumps.
EIRP: Defines the Equivalent Isotropic Radiated Power emitted by this data link.
Gain: Defines de antenna transmission gain, in dB
Frequency: Defines the transmission frequency, needed to calculate the free space losses.
Link type: Two types are considered
- VIA DRS: For communications via Data Relay Satellite. It implements the link via another satellite.
- DIRECT: For direct communications with a ground station antenna.

Horizon mask: It defines the minimum elevation at which data contact is possible. The horizon mask is optional, and is defined as a string of [Azimuth, Elevation] pairs separated with semicolons, e.g. 0.00, 0.20 ;5.00, 0.20 ;10.00, 0.20 ;15.00, 0.30 ;20.00, 0.40.
Constraints: A datalink may be subject to the following constraints:
- Duration: to constraint the duration of every single communication event
- Exclusive group: to avoid simultaneous dumps on different datalinks for the same satellite
- Gap: to constraint the gap between consecutive dumps.
- Quota: to implement quotas of usage a each datalink
- Transitions: to constraint the transition times between activation of datalinks.
Restrictions: It allows defining a subset of ground station antennas that can operate with the datalinks.

Creating and editing datalinks

Datalinks horizon masks

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