Methods of synchronization for an unknown signal sequence by learning procedure, which computes a posteriori probabilities for the signal location, are presented. First, to avoid the difficulties of the interference between successive intervals, a signal sequence with ample guard spaces for getting rid of the interference is treated. Next, the case without guard space is treated. To the nonsupervised case, some methods are applied. The methods proposed in this paper have a form of double learning with respect to the unknown signal form and the signal location. Also some results of computer simulation are presented.