1. A method for receiving a digital stream by a receiver, the stream comprising frames, each frame having a body composed of a variable quantity c of symbols preceded by a header having a total quantity d of symbols, the header comprising at least one known field of which the receiver has a priori knowledge, and at least one unknown field of which the receiver does not have a priori knowledge, the at least one unknown field composed of a fixed quantity e of symbols and encoded such that the receiver has a priori knowledge of a first relationship between certain groups of the e symbols and of a second relationship between certain other groups of the e symbols, the method comprising: a) storing, by the receiver, at least one series of symbols of the digital stream including at least a portion of the d symbols of the header; b) performing, by the receiver, a first correlation computation on at least a portion of the at least one series of symbols, wherein the first correlation computation is based on the a priori knowledge of the first relationship between the certain groups of the e symbols; c) performing, by the receiver, a second correlation computation on at least a portion of the at least one series of symbols, wherein the second correlation computation is based on the a priori knowledge of the second relationship between the certain other groups of the e symbols; d) determining a correlation level based at least on a combination of results of the first and the second correlation computations; and e) comparing the correlation level against a threshold level and, based on a result of that comparison, determining frame synchronization for the at least one series of symbols.