Directly modulated CATV transmission systems using half-split-band and wavelength-division-multiplexing techniques

We present a directly modulated NTSC AM-VSB 80-channel fiber optical CATV long-distance (over 80 km) transmission systems by using 1550-nm digital distributed-feedback laser diodes, half-split-band, wavelength division multiplexing and erbium-doped fiber amplifier-repeated techniques. Good performances of carrier-to-noise ratio (/spl ges/50 dB), composite second-order (/spl ges/68 dB), and composite triple beat (/spl ges/63 dB) are obtained after 80-km standard single-mode fiber transmission. The proposed directly modulated transmission systems are simpler and lower cost than conventional externally modulated transmission systems.