Instead of transmitting control surface positions over a standard RC link, the LRC base digitizes the control signals and sends them to the autopilot, where the autopilot turns them into signals that the servos can use.
The LRC transmits RC control information over two radio modems so that you can still control your UAV in the event that one of the datalinks fails or is blocked by another user on the same frequency. Even frequency-hopping transmitters can take some time to hop to a different frequency in the event of interference.
Both the 2x28LRC and the 2128LRC allow eight channels. The autopilot can control 16 additional channels 8 of which are set up to control servos, and the final 8 are set up as on/off switches with high-side drivers.