# Cmput: 2D parity error detection scheme

1. Dec 12, 2007

### hkstyles

Question Details:
The following blocks have been encoded using the two-dimensional parity error detection scheme. That is, the rows have been encoded using odd parity and the last row holds the parity bits of the columns which have also been encoded using odd parity. There are two possible interpretations of the corner parity bit in the last block – it can either check the row or column parity. In this example, it has been used to check the column parity.

a) Is an error detected?

b) If there is an error (or more than one errors) detected: are there conditions where the error or errors can be corrected? If there is no error detected, could there have been errors that were not detected?

c) How many overhead bits are there in this example?

1 0 1 1 1 0 0 1
0 1 0 0 1 1 0 0
0 0 0 0 0 1 1 1
1 1 1 0 0 0 0 0
1 1 1 0 1 1 0 1

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also.. :
The following message bits are to be transmitted: 11010001010001001010. It is decided to split this message into blocks of 5 bits and apply the two-dimensional parity error detection scheme using even parity. Show the encoded blocks that would be transmitted.

2. Dec 13, 2007

### l46kok

You have to show your work if you want to receive detailed help.

Here's something to start you off. Recall the definition of odd parity. The parity bit is set to 0 if you have an odd numbers of ones and it is set to 0 if you have an even number of ones.

In your case, the last row (bottom) and the last column (to the right) are the parity bits. Compare each row and column and see if you find any contradictions. If you do, then t here has been an error in the transmission.