Characterization of TWTA nonlinearity by means of a time-domain correlation method

The use of advanced coding and modulation schemes devised by the DVB-S2 standard, together with the multi-carrier operation of the payload traveling-wave tube amplifiers (TWTAs) and the use of complex RF front-ends calls for a detailed assessment of nonlinearity effects on the end-to-end performances. In these scenarios, TWTAs saturation power and relevant operating points must be optimized according to the actual, operational scenario. For this purpose, we developed a simulator tool to analyze the impact of payload nonidealities on the end-to-end link performance. The impairments introduced by the payload in the reference signal are estimated by the Carrier-to-intermodulation ratio obtained by means of cross-correlation techniques. The modeling methodology has been applied to the TWTA characterization and optimization with respect to multicarrier DVB-S2 operation.