光ケーブルテレビシステムにおけるクリッピング歪の持続時間特性とディジタル伝送特性に与える影響(<論文小特集>ディジタル伝送)

概要

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In a hybrid analog(AM-VSB)/digital(QAM)sub-carrier multiplexed(SCM)optical cable TV system, clipping-induced impulsive distortion occurs when the SCM signal's amplitude drops below the laser-diode(LD)threshold. This distortion may induce bursts of bit errors in digital channels. We have investigated the duration of clipping-induced distortion and its effect on the BER performance of QAM signals. As a result, we found that the frequency accuracy of the analog sub-carriers is one of the main factors that characterize the clipping-induced impulsive distortion which affects the performance of the digital channel. The more accurately the frequencies of the analog sub-carriers are set, the longer the duration of the clipping-induced distortions becomes, If the duration exceeds the ability of the forward error correction (FEC) system, the FEC system will not work well because of the error bursts. This factor has not been considered in previous approaches.
社団法人映像情報メディア学会の論文
1998-11-20