Investigation of nonlinear effects in the transmission of a QAM signal in fibre optic communication lines using different carrier pulses

We study the transmission of a quadrature amplitude modulation signal over a fibre-optic communication line for different carrier pulses forming a signal. It is shown that in using 'raised cosine' and 'root raised cosine' pulses, it is possible to further reduce the bit error rate by an order of magnitude with the help of a special modulation format.