Abstract: In a method of synchronizing synchronous digital bit streams each comprising bits each having the same duration, one of the bit streams is taken as a reference. This provides a basis for defining successive reference time intervals each equal to the bit duration. A plurality of timing windows are defined within each reference time interval. A second bit stream is subjected to a time-delay that can have a null or zero value. One of the windows is taken as a reference window on the basis of a required phase relationship between the reference bit stream and this second bit stream. The phases of the reference bit stream and the second bit stream are compared to determine a window containing the beginning of each bit of the second bit stream. The time-delay, if any, to be applied to the second bit stream is determined on the basis of this window.