Hybrid AM-VSB/M-QAM multichannel video transmission over 120 km of standard single-mode fiber with cascaded erbium-doped fiber amplifiers

A 120-km standard single-mode fiber, multichannel hybrid AM-VSB/64- and 256-QAM video lightwave trunking system, which employed an externally modulated DFB laser transmitter with built-in erbium-doped fiber amplifier (EDFA) and two in-line cascaded EDFAs with a total link budget of 35 dB, has been demonstrated. With the in-line EDFAs operating in deep saturation a simultaneous transmission of 79 AM channels with CNR >49 dB with negligible CSO and CTB distortion degradation, and four 256-QAM channels with low bit-error rate (BER <10/sup -9/), has been achieved. In addition, unlike the 64-QAM case, the use of a forward error-correction code in the 256-QAM modems is essential in a fully loaded 750-MHz (79 AM and 33 256-QAM channels) video lightwave trunking system.