Digital radio link: Comparison of the resistance of two different 4-phase modulation forms to multipath propagation

Two 4-phase modulation forms were compared with respect to the resistance to frequency selective fading generated by simulated multipath propagation. As wave propagation model for digital microwave radio link exposed to tropospheric anomalies, a simplified three-way model was chosen. The validity of the model was confirmed by spectrum measurements on existing linkhops. The comparison between the different modulation forms focuses on different measures which characterizes the accessibility of the systems during periods of frequency selective fading.