Adaptive equalization of troposcatter channels with FSK modulation: Part 1. Theory and computer simulation

The basic concept of an adaptive equalizer particularly suited for troposcatter channels with FSK modulation is presented. The three main features of the equalizer are: (1) a new error criterion which needs no explicit carrier synchronization; (2) a new nonlinear feedback branch for improving the equalizer performance and (3) a transversal filter structure, which uses only real coefficients for bandpass signals. The theoretical background of these features is sketched. The performance characteristics of the new equalizer are demonstrated and compared with the performance of conventional equalizers by discussing some simulation results for a data rate of 8.448 Mbit/s.