SkyNet sends instructions to your drone via the internet or SMS.
How it works
Each drone has a "Chain of Command" with higher priority commands overriding lower priority commands.
A typical drone Chain of Command, with highest priority at the top:
SkyNet gives the APM new instructions. The APM decides to execute the new function.
From an internet location a user sends SKYNET_LAND to their drone.
SkyNet picks up the instruction and sends it to the APM unit via MavLink
The APM agrees and sends back current GPS coordinates to MavLink.
The SkyNet device picks up the GPS coordinates and sends them back to the user over the internet.
User->Internet -> SkyNet -> APM ->SkyNet->Internet->User
The SkyNet Transceiver
The SkyNet transceiver can be connected directly to the APM via a DroneLink cable, or via a Telemetry groundstation link in the vicinity;
Each SkyNet transceiver can both receive and transmit data, and is usually a mobile phone type device with integrated GPS, GSM, messaging system.
The SkyNet app forwards user instructions to other SkyNet Transceivers until the instruction receives the targeted Drone. The instructions can be direct input, SMS, or via radio telemetry link connected to the device.