ed. The required SNo results to be 20 dB before FEC operation, smaller than the 24 dB result- ing from the draft design. This gap generally exists in long-haul systems since it is used to allocate other components in the gap between the stages of in-line amplifiers, like OADMs. Just to do an example, let us image that we have to place in four of the intermediate sites one OADM for branching that introduces a loss of dB. This loss has to be balanced by a greater gain of the EDFAs SO generating more noise. Carrying out the draft design, by introducing these new components, we see that the SNo deriving from this new analysis is equal to 21.9 c thus getting much nearer to the bottom line for the system working. 6.3.2.1.5 Erbium-Doped Optical Fiber Amplifier Amplified Systems Design: Simulation The system design coming out from the considerations of Table 6.4 has been simulated using two different simulation programs. Telecommunication Networks TABLE 6.4 Realistic Penalty Analysis for Long-Haul 10 Gbit/s Dense Wavelength Division Multiplexing System Long-Haul 10 Gbit/s DWDM System System length 3500 km Channel speed 10 Gbit/s Suitable EDFAs, span length 60 km, RS(255,239) FEC Channel spacing 50 GHz Extended C band, 38 nm in the third window, that is 4560 GHz, 90 channels @ 10 Gbit/s Ideal SN (dB) (Be=2R) NRZ modulation Optical to electrical Main contribution two Gaussian AWG with a unilateral bandwidth ratio passband of 20 GHz (bilateral 40GHz 2 0.33nm @ 1.55 um) Ideal SN, (dB) Penalty in dB Transmitter dynamic SFF MSA using tunable CW laser and LiNbO3 modulator range APD diode noise + shot noise Linear crosstalk Gaussian selection filter (AWG), Bo = 4R Channel spacing Af=5R=50GHz (see Figure 6.16) Nonlinear crosstalk Use of SSMF to thwart FWM, post-compensation with DCF From Equations 6.44 and 6.45 adapted to this case SPM and chromatic Under compensation of chromatic dispersion at 98% dispersion interplay NRZ modulation Aging System margin Polarization effects PDL, connectors misalignments, etc. Total SN post code 2