EXtrinsic Information Transfer (EXIT) charts are useful for characterizing the convergence properties and the performance of turbo receivers. Turbo receivers are generally constructed from two or more Soft Input Soft Output (SISO) modules. By simulating a single SISO module, the transfer characteristic of the SISO module can be obtained using the EXIT class. The transfer characteristics of two SISO modules represented on the same figure by switching the axes give the EXIT diagram.