Thanks to the message passing principle, turbo decoding is able to provide strong error correction near the theoretical (Shannon) limit. However, the minimum Hamming distance (MHD) of a Turbo Code may not be sufficient to prevent a detrimental change in the error rate vs. signal to noise ratio curve, the so-called flattening. Increasing the MHD of a Turbo Code may involve using component encoders with a large number of states, devising more sophisticated internal permutations, or increasing the

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... dimension of the Turbo Code, i.e. the number of component encoders. This paper addresses the latter option and proposes a modified Turbo Code, in which some of the parity bits stemming from the classical component encoders are encoded by a rate-1, third encoder. The result is a significantly increased MHD, which improves turbo decoder performance at low error rates, at the expense of a very small increase in complexity. In the paper, we compare the performance of the proposed Turbo Code with that of the DVB-RCS Turbo Code and the DVB-S2 LDPC code.