Inter-Satellite Links Tutorial
Complexity: | High |
---|---|
Payloads: | 2 satellites with ISL & SABERTOOTH |
Windows: | LEASE_ISL & PAYLOAD_SABERTOOTH |
Inter-Satellite Links (ISL) are enabled for some satellites. ISL links can be made between a single pair of satellites following the same orbit so that they can be in contact at any time, where there is little relative motion between them. Satellites that are in intermittent contact (i.e. when their orbits overlap) may also be used for ISL contacts, so long as their direction is similar enough for meaningful contact time as well as low doppler-shift.
To simplify calculating when to schedule the windows, for this example we will be assuming that the satellites are in synchronous orbit.
Prerequisites
All tutorials require the steps outlined in the Getting Started Guide. Additionally the zfec
python module must be installed on the payload. See the In-Orbit Python Environment Setup
instructions for more information.
Scripts
deploy
- run by the user on the ground to uploadisl_tx_demo
&isl_rx_demo
, and schedule them to execute in aPAYLOAD_SABERTOOTH
windowisl_tx_demo
- Runs on the transmitting payload/satellite to send dataisl_rx_demo
- Runs on the receiving payload/satellite to receive data
Upload & Deploy
The deploy
script is run by the user and performs the following steps:
- Uploads
isl_tx_demo
&isl_rx_demo
scripts to the respective satellites - Schedules an ISL between 2 satellites in 24 hours
- Schedules a
PAYLOAD_SABERTOOTH
window to run on the transmitting satellite to send data - Schedule a
PAYLOAD_SABERTOOTH
window to run on the receiving satellite to listen for & downlink data
$ ./deploy "[AUTH_TOKEN]" [SAT_ID_TX] [SAT_ID_RX]
Schedule LEASE_ISL
The LEASE_ISL
is used to configure a one-way Inter-Satellite-Link using the S-BAND radio, providing a simplex IP link between the satellites. In this example UDP is used for data transfer as the protocol has no return acknowledgment and ideal for simplex links.
A single call to the Tasking API creates a LEASE_ISL
in both satellites. For this example satellites FM1
and FM2
are scheduled for 5 minutes. Everything is scheduled 24 hours out when there are no conflicts with existing down-link contact windows.
Review
Once the window has completed and enough time has passed for the log to download, it can be reviewed in AWS S3 (see Hello World tutorial).