Posted by: atri | January 24, 2012

## Lect 3: More on Parity and Repetition Codes

On Monday, we studied the error correctability (and detectability) of the parity and repetition codes. We also looked at some ways of modeling noise. The material was from Sec 1.3 in the book.

A reminder that tomorrow, Jesse will present the lecture. He will talk about the distance parameter of a code.

## Responses

1. I couldn’t understand the part which states the relation between the error pattern and size of the alphabet in section 1.3.1

//
If the error pattern is (1,0,1,0,0,0) and alphabet is {0,1} then it has 2 errors. if alphabet is {0,1}3 then it has only one error.
//

• HI Praveen,

Hopefully the binary part is clear: if you look at the vector $(1,0,1,0,0,0)$ then it has two non-zero values and hence has 2 errors. However, if we think of the vector as $((1,0,1),(0,0,0))$— i.e. the vector only has two symbols each from $\{0,1\}^3$, then this vector has only one non-zero symbols and hence, has one error.

Does the above make more sense?

2. Hello Professor,

Now, I understood it completely .Thank you

• OK, great. You’re welcome.