AGC strategy for adaptive digital modems employing cyclic channel estimation in an HF frequency hopping scenario

An automatic gain control (AGC) strategy is proposed for modems employing adaptive cyclic channel estimation to facilitate high-speed (2400 bit/s) digital communications in HF frequency hopping (HF-FH) applications. The technique effectively eliminates signal amplitude variations which may occur at the transitions between successive hops as a result of the different fading characteristics of typical HF channels in frequency slots separated by more than the correlation bandwidth of the channel. Simulation results are presented to demonstrate the AGC procedure in an idealised test setup, as well as in a simulated HF environment with FH. The results suggest the possibility of applying the technique to a variety of applications which exhibit similar amplitude transient phenomena.<>