The results showed the smaller bandwidth was required by using NRZ format, while better performance of the RZ format was obtained to withstand fiber non-linearity effects. The effects of amplified spontaneous emission in the networks with the RZ, the NRZ, and the CS-RZ modulation formats were evaluated by using an Erbium-doped fiber amplifier (EDFA). They reported that transmission distances of 400 km and 1200 km with bit rate of 40 Gb/s are feasible within the RZ- and the NRZ-modulation formats. Another comparison between the RZ and the NRZ modulation formats for 40-Gb/s time division multiplexing (TDM) system, showed that for upgrading the existing network to 40-Gb/s, the RZ-modulation format is superior compared to conventional NRZ-modulation. A comparison between the NRZ and the RZ data formats with respect to polarization mode dispersion (PMD)-induced system degradation showed the RZ performance better than the NRZ. The results showed the NRZ format had a similar tolerance to intersymbol interference due to the interaction of dispersion and nonlinearities as that of RZ and CS-RZ formats without FEC.
DATA COMPARISON ON MATLAB AND OPTISYSTEM CODE
Another study has been done to compare standard forward error code (FEC) in 40 Gb/s optical transmission systems with NRZ, RZ, and carrier-suppressed RZ (CS-RZ) modulation formats. The results showed that NRZ pulse shape was superior compared with RZ for duobinary transmission in all the cases that were studied including systems that are limited by amplified-spontaneous noise, fiber chromatic dispersion and self-phase modulation. In a study, the RZ and the NRZ techniques have been compared in an optical duobinary system. Also, while the NRZ is more economical, the RZ, on the other hand, is more tolerant to nonlinearity than the NRZ. In a simple comparison, the NRZ technique requires less bandwidth for transmission than the RZ and it is not sensitive to laser phase noise. Introduction Return to zero (RZ) and non-return to zero (NRZ) are the popular techniques, which are used to encode optical pulses in optical networks.
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