Performance of hybrid multichannel AM/256-QAM video lightwave transmission systems

We report experimental results on the performance of a multichannel hybrid AM/256-QAM video lightwave transmission system. Performance limitations due to impulse noise using a directly-modulated DFB laser transmitter and an externally-modulated YAG laser transmitter are presented. We also compared the BER characteristics of 256-QAM versus 64-QAM signals with either CW carriers or modulated video signals in such a hybrid system. Our results indicate that 64-QAM signal performance is more robust than that of 256-QA as expected. Significant 256-QAM BER degradation is observed with modulated AM-VSB video signals, making it necessary to use forward-error-correction code for robust 256-QAM transmission.<
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