Abstract

Today, a mode of digital compressed-video transmission is expected to be adapted to optical video distribution systems. From this perspective, digital modulation methods have been widely considered. On the whole, M-ary quadrature amplitude modulation M-QAM seems promising because of its high bit-rate efficiency per unit bandwidth.¹ However, there has been exposed a certain limitation on bit error rate (BER) arising from the laser-diode (LD) clipping distortion. Instead, quadrature phase-shift keying (QPSK) was studied in terms of its application to digital modulation. This paper presents an experimental study of the BER characteristics of 6-Mbit/s QPSK signals, subject to various CTBs induced by multichannel virtual- sideband-AM (VSB-AM) optical transmission.

© 1994 Optical Society of America