LRC - Longitudinal Redundancy Checking
Adds an additional character (instead of a bit)
- Block Check Character (BCC) to each block of data
- Determined like parity but, but counting longitudinally through the message (as well as vertically)
- Calculations are based on the 1st bit, 2nd bit, etc. (of all characters) in the block
- 1st bit of BCC ? number of 1’s in the 1st bit of characters
- 2nd bit of BCC ?number of 1’s in the 2ndt bit of characters
Major improvement over parity checking
- 98% error detection rate for burst errors ( > 10 bits)
- Less capable of detecting single bit errors