Two problems concerning synchronization for DS1 extended superframe format digital transmission are analyzed. The first problem is to determine how long it will be before synchronization is perceived as being lost given the probability of a bit being in error. The second problem is a special case of the first problem in reverse: given that a synchronization failure has been detected, how long ago did the synchronization really fail? It is shown that a critical parameter for both of the problems is window size, i.e., the number of framing bits that are used to track synchronization. Numerical results and a possible application of the first problem are discussed.>