Turbo-codes are error-correcting codes used in power­ful digital transmission systems to ensure a low binary error rate. This paper presents different approaches aimed at recovering a convolutional encoder in a non-cooperative context like in military interception or cognitive-radio applications. In this context, the intercepted data are the only known information. It also explains the residual inde­termination due to “equivalent” coders and it gives the link between an NRNSC encoder and its RSC equivalent form. Furthermore, it reports on a new approach developed to recover the interleaved version of the second encoder of a Turbo-code when its systematic outputs are punctured.