mmarized in Table 6.15 for 315 km of SSMF fiber SO that the total system length results to be 355 km. For this system, the draft design estimates an SN, of 17.7 dB. The summary of the penalties analysis is reported in Table 6.16 requiring an SNo of 16.7 dB, in good agreement with the simulation estimate. At the end, it is possible to conclude that the system is feasible and its reach is 355 km, versus the 320 km achieved with IM-DD. Two main observations can be done comparing this example with that of the previous section: the first is that the sensitivity advantage of the DPSK is almost all counterbalanced by the bigger losses at the receiver, while the use of NRZ instead of RZ has allowed reduc- ing significantly the noise contribution. TABLE 6.15 Results of the Draft Design of the All Raman Single Span Differential Phase Shift Keying System Maximum transmitted power per channel 15 mW Pump 1 power-receiver 480 mW Pump 2 power-receiver 370 mW Pump 1 power-transmitter 470 mW Pump 2 power-transmitter 360 mW Pump 1 power-SSMF 650 mW Pump 2 power-transmitter 500mW DCF length transmitter DCF length receiver Total length traveled by pumps in SSMF Equivalent amplifier length in SSMF Raman gain transmitter Raman gain receiver Telecommunication Networks TABLE 6.16 Penalty Analysis of the All Raman Single Span Differential Phase Shift Keying System All Raman Single Span System at 10 Gbit/s with DPSK and SSMF Pumping 10 Gbit/s Notes Channel number Extended C band Channel spacing Modulation format DPSK modulation Ideal SN (dB) Required SNo (dB) Impairment Penalty (dB) Notes APD receiver noise This is mainly the avalanche noise (see Equation 5.29), due to the low power on the APD (-20 dBm per channel) Signal dynamic range Lithium niobate modulator-Phase modulation eliminates Raman dynamic compression Linear crosstalk AWG multistage, signal spectrum Gaussian with spread of 10 GHz, Gaussian optical filter with 15 GHz width, see Figure 6.16 Nonlinear crosstalk (FWM XPM) Wide spacing (100GHz) and use of an SSMF Residue chromatic