Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 15

A 3B4B code converts blocks of 3 bits to blocks of 4 bits according to the rules given in Table 4.3. When there are two or more consecutive blocks of three zeros, the coded binary blocks 0010 and 1101 are used alternately. Similarly, the coded blocks 1011 and 0100 are used alternately for consecutive blocks of three ones.
( a ) Using these translation rules, find the coded bit stream for the data input 01000 1111111101000000001111110.
( b ) What is the maximum number of con­secutive identical bits in the coded pattern