6. An apparatus as claimed in claim 5, the sync word generator means being adapted to generate the following sync words: TBL ______________________________________ 1 11100011111110 6 2 10100011111110 6 3 01100011111110 6 4 01011100000001 1 5 10011100000001 1 6 00011100000001 1 7 11000100000001 1 ______________________________________ where the value in the first column indicates the coding state after having converted the information word directly preceding the sync word to be added, the bit sequence in the second column indicates the sync word generated in response to said coding state and the value in the third column indicates the coding state required to obtain the codeword directly following the sync word.
6. An apparatus as claimed in claim 5, the sync word generator means being adapted to generate the following sync words: TBL ______________________________________ 1 11100011111110 6 2 10100011111110 6 3 01100011111110 6 4 01011100000001 1 5 10011100000001 1 6 00011100000001 1 7 11000100000001 1 ______________________________________ where the value in the first column indicates the coding state after having converted the information word directly preceding the sync word to be added, the bit sequence in the second column indicates the sync word generated in response to said coding state and the value in the third column indicates the coding state required to obtain the codeword directly following the sync word. 18. An apparatus as claimed in claim 6, wherein the sets of code words belonging to each pair of coding states of the first type are disjunct.