Improvement eye diagram opening by base band pre-distortion over nonlinear channel in DVB-RCS transmitter

This paper presents the design procedure and laboratory results for a baseband pre-distortion method. This design consists of 32QAM modulation in nonlinear satellite channel for DVB-RCS Earth Station Transmitters. It is concluded that by predistorion of modulation constellation in transmitters, we will be able to get an undistorted constellation at the output of satellite TWTA. We compare the BER performance of 32-QAM Modulation in predistotion and non predistortion cases. By utilizing the proposed method in a saturated TWTA, there is only 4dB difference between theory and simulated results. The simulation results of proposed method show that the eye diagram using PD is opened as 5 times. The laboratory results show 4-times improvement in the rate of opening eye diagrams for proposed method.