A new approach to QPSK: mechanism, simulation and implementation

The work reported in this paper serves two purposes. First, an alternative comprehensive approach is proposed for the understanding of the mechanism behind QPSK. This focuses on how a QPSK modulator decides to represent each pair of bits to be transmitted, by which of its four possible phase shifts. This approach is based entirely on the analysis of phasors and is completely mathematics-less. The second part of this work proposes a method by which complex modulation schemes, like QPSK, can be implemented using only first degree components in Simulink, avoiding all the hurdles of mathematically complicated blocks. The implementation, in the second part, confirms the viability of the approach in the first part of this work. Results show that the data received on the other end of a noiseless channel exactly matches the data sent despite a slight unavoidable delay. The proposed method for implementing QPSK can be used directly as a laboratory exercise for undergraduate students new to digi