Digital Communications 2

7Study of a QPSK Modem Under MATLAB, Simulink, Communications and DSP

7.1. Objective

The objective of this lab work is the study, then the simulation under MATLAB, Simulink, Communications and DSP of a QPSK digital transmission modem (modulator and demodulator).

The complexity of telecommunications and signal processing systems has grown enormously in the last two decades.

The evaluation of performance on “hardware” prototypes is of course the best method to validate a concept, a structure or system. However, this approach is usually very time-consuming and expensive in terms of equipment. It is therefore understandable why the implementation phase intervenes only at the end of the development cycle.

The role of simulation is precisely to perform all these tests, at a lower cost both in terms of time and equipment.

The objective here is the study and the complete simulation of the proposed QPSK modem (see the block diagram in the Appendix).

The QPSK modem in question uses the following software modules, MATLAB, SIMULINK, COMMUNICATIONS and DSP:

• – MATLAB:
  • - analysis, design, optimization;
  • - off-line data processing;
• – Simulink:
  • - block diagram modeling;
  • - off-line simulation;
• – Communications Toolbox (uses: SIMULINK and MATLAB): modeling and simulation of all the components of a digital or analog communication system “commlib”;
• – DSP Blockset (uses: MATLAB, SIMULINK, SIGNAL PROCESSING TOOLBOX): set of libraries specific to signal processing. They are used by SIMULINK ...