An intelligent gain controller (IGC) for an on-frequency repeater implements a method for identifying a desired narrow band signal within a broadband RF signal. Thus, a candidate narrow band signal within the broadband signal is isolated. The isolated narrow band signal is then processed to detect repeating features of the narrow band signal. The detected repeating features are then analyzed to identify the signal type of the isolated narrow band signal. System gain of the in-frequency repeater can be controlled based on the power level of the identified narrow band signal.