Each letter of the alphabet is coded thus: it is first represented in 3-bit mod 4 so that A=000, B=001, C=002, D=003, E=010……Z=121 and space = 122. Each 2 is then replaced by and each 3 by a . 0 and 1 remain unchanged so now for example, D= and Z= . The string for each letter then has two check digits put on the end using your matrix in 5.

I have to do this question but i confuse and i do know what to do please someone help me??????