“Performance Investigation of NRZ-DQPSK, CSRZ-DQPSK and MDRZ-DQPSK Modulation Techniques for 450 Channel UD-WDM System for Long Haul Communication: ANALYSIS OF MODULATION TECHNIQUES FOR LONG HAUL UD-WDM SYSTEM”. 2023. Journal of Scientific & Industrial Research (JSIR) 82 (08): 870-84. https://doi.org/10.56042/jsir.v82i08.1053.