From Newtec Senior Engineer Guido Verfaillie –

“The DVB-S2 standard as described in ETSI EN 302 307 is based on powerful error correcting codes, a wide range of code rates, 4 constellations and 3 roll-off factors. The QPSK and 8PSK modulation schemes can be operated close to or at saturation, but 16- and 32APSK modulated signals show larger envelope variations and are more sensitive to channel impairments due to non-linearities present in the chain. The power efficiency of the latter modulations can be improved by introducing predistortion on the transmit data and avoiding large IBO/OBO values in this way. Linear distortions caused by amplitude and group delay variations over the signal bandwidth can be minimised by equalising.”

Please download the complete White Paper here – White_paper_Improving_the_transponder_utilisation_February2008

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