In this article a simulation environment for digital transmission systems is presented. Its application in digital transmission experimental learning is possible by allowing key parameters influence study through a graphical interface. It is possible to visualise some points of the system, modify structures and transmission parameters. Equivalent lowpass of BPSK and QPSK with limited Nyquist spectrum and nonlimited spectrum (finite time impulses) are considered. Fast BER curve estimation is obtained by a semi-analytical procedure.

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