An AGC strategy for adaptive digital modems in frequency hopping applications

A novel AGC (automatic gain control) procedure is proposed for adaptive digital modems operating in the frequency-hopping mode. The proposed technique provides an effective solution to the AGC amplitude transient problem. When it is combined with amplitude- and phase-correction capabilities of the modem receiver equalizer, the digital HF modem receiver performance can be significantly improved. Simulation results demonstrate the performance of the AGC procedure in an arbitrary test setup, as well as in a simulated HF environment with frequency hopping. The results also suggest a wide variety of potential application areas in which the proposed AGC scheme can be applied with success, the only requirement being the establishment of some form of synchronization to mark the approximate location of the amplitude discontinuities