# finding the overhead and distance of an unknown code based on message making algorithm

for an information word M with m bits that is coded as following:

• M is coded into a word A using an unknown code that allows detection of not more than one error.
• the code word is the word obtained by a concatenation of A to itself. so A becomes AA and etc..

1)is it possible to know the overhead in the given code?

2)is it possible to know the distance of the code?

EDIT: I don't know how to solve it and i've tried several times and apparently i am going to the wrong directions. please solve it if you can so i can learn the correct way of approaching and solving this kind of questions.

thank you very much

my attempt:

after thinking on it again and rereading the text, i began to realize(hopefully i am right now) that the question is about parity bit and not hamming. so if it can detect not more than one error, there's a parity bit, i think. based on that thought i tried to solve it:

1)I began to realize it's not about hamming code. if we can only detect not more than one error, then it's about the parity bit. so i think that if we add a bit to each byte of message, then the overhead will be 9 bytes total. so it can be calculated, i think.

2)since this sub problem is about the concatenation of A to itself, then like @YuvalFilmus said, the minimal distance should be twice now.