Abstract: A method and device for counting the number of consecutive data symbols in a stream of data bytes, the device comprising a main counter for maintaining a count which is incremented/decremented for each respective consecutive data byte of said stream and adjustment means for incrementing/decrementing the count of the main counter, after every occurrence of a predetermined number of consecutive data bytes, by an adjustment value determined according to the ratio of the number of bits in the bytes to the number of bits in the symbols, such that the count represents a count of data symbols and a method and device for generating a synchronization signal from a received MPEG data stream with a MAC message containing an Upstream Slot Marker Pointer, the device including the above counting device, a controller for starting main counter according to a received MPEG synchronization signal and synchronization means for generating the synchronization signal once the main counter has counted the number of symbols indicate