Long-Distance Transmission of Directly Modulated 1550nm AM-VSB CATV Systems

Abstract

This study presents a directly modulated 1550 nm NTSC AM-VSB 74-channel Wber optical CATV long-distance (over 100 km) transmission system. In this system, 1550 nm analog distributed feedback (DFB) laser diodes, push-pull preampliWer, half-split-band, wavelength-division-multiplexing (WDM), and in-line erbiumdoped Wber ampliWers (EDFAs) were used. Performances of carrier-to-noise ratio (CNR) of ¶ 49 dB, compositie second order (CSO) of ¶ 70 dB, and composite triple beat (CTB) of ¶ 65 dB were obtained over 100 km of standard single-mode Wber (SMF) transmission. This proposed directly modulated transmission system is simpler and more cost-eVective than conventionally externally modulated 1550 nm transmission systems.For long-distance AM video transmission in ® ber optical CATV systems, the maximum ® ber link length using cascaded in-line erbium-doped ® ber ampli® ers (EDFAs) is limited by AM-VSB video system RF parameters such as carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple beat (CTB) at the end of the ® ber link. These parameters are seriously degraded by stimulated Brillouin scattering (SBS) and ® ber chromatic dispersion eOE ect in 1550 nm AM-VSB ® ber optical CATV systems [1,2]. Several ways have been proposed to improve system performances such as using diOE erential detection at the receiver site [3] or using dispersion compensation ® ber (DCF) within the link [4]. However, for the former one, an additional set of an expensive externally modulated transmitter, a ® ber link, and an optical receiver are required, while poor CNR quality may be induced in the latter one due to high loss characteristics of the DCF. Moreover, it is di cult to obtain good CNR, CSO, and CTB performances for the full channel loading simultaneously. In this study, a directly modulated NTSC AM-VSB 74-channel system 279 Fiber and Integrated Optics, 20:279± 285, 2001

Simultaneous Transmission of AM-VSB CATV and Internet Access Signals over the Existing Multimode Fibers in the Campus

“…This improvement results from to the use of 1 channel transmission. There will be without any CSO and CTB product counts exist in any in-band channel (CH3), and the off-band CSO and CTB product counts will have no influence on other channels [5]. Therefore, by using am optical receiver was > 1.71 and > -1.34 dBm, respectively.…”

350 km Transmission of 15-Channel 256-QAM Signals

“…Extending the transmission distance is the goal of the fiber optical CATV system operators, however, the maximum fiber link length (-150 km) using cascaded inline erbium-doped fiber amplifiers (EDFAs) is limited by AM-VSB video system RF parameters such as carrierto-noise ratio (CNR), composite second order (CSO) and composite triple beat (CTB) at the end of the fiber link [1][2]. If the fiber optical CATV system operators want to extend the transmission distance, conventionally they must use video codec equipment to transmit the video signals in a digital lightwave network [3].…”