Abstract :
Bandwidth and power are limited resources to satellite communication systems. Satellite communication systems also have two different polarizations: vertical polarization and horizontal polarization. These polarizing differences will result in Cross Polarization Interference (CPI) resulting in a decrease in transmission signal quality. CPI occurs due to pointing antenna errors or satellite position shifts. Therefore, it is necessary to pay attention to the pointing stage of the antenna so that there is not a large enough interference that results in a copy to another transponder link. This can be done by keeping prisoners in isolation between vertical polarization and horizontal polarization worth ≥30dB. In the research analysis of optimization stages in the Cross Polarization process aims to determine the influence of CPI values obtained on the main carrier based on changes in the stages of cross polarization and selection of QPSK, 8PSK and 16 QAM on transponders that are reviewed in terms of Bandwidth and power in order to be efficient to the percentage of usage. The method in this study was determined by the parameters Energy Bit Noise to Ratio (Eb/No), Carrier to Noise Density Ratio Total (C/N)Total and Carrier to Interference Ratio Total (C/I)Total in the state before and after optimization. Based on the results of the analysis, 8PSK modulation techniques with Forward Error Correction (FEC) 7/8 resulted in the most optimal percentage of power and Bandwidth usage of 4,85% for power expansion and 4.76% for Bandwidth usage. The result of cross polarization optimalization conducted using 8PSK modulation technique with FEC 7/8, C/N value produced by 20.26 dB, Eb/No 16,28 dB and BER 5,59x10-9 . Keywords: Optimization, Bandwidth, Power, Cross Polarization, Satellite.