Rx2 Automatic Gain Control (AGC) mode select. If in AGC RF Level mode, the AGC control loop will adjust the RF gain to maintain a constant RF power output If in AGC RLL (Received Light Level) mode, the receiver will attempt to compensate for the optical loss by adjusting the modules RF gain, and the AGC Target is not used (instead the SGC gain setting may be used to set a module gain target)