The full form of LRC is Longitudinal Redundancy Check.
Longitudinal Redundancy Check (LRC) Explained
LRC is a type of error detection method used in data transmission and storage. It's a form of redundancy check, applied to parallel bit streams. Think of it as adding an extra layer of verification to ensure the data's integrity.
How LRC Works
In telecommunication, Longitudinal Redundancy Check (LRC), also sometimes called Horizontal Redundancy Check, works by:
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Calculating a parity bit for each bit position across a block of data. This is different from a standard parity check, which calculates a parity bit for each byte or character.
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These parity bits are then assembled into an LRC character, which is appended to the end of the data block.
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The receiver performs the same calculation on the received data and compares its LRC character with the received LRC character. If they match, it indicates that the data was likely transmitted without errors.
Example
Imagine you are sending the following data:
Byte 1: 10110010
Byte 2: 01011001
Byte 3: 11000111For each bit position (from left to right), you'd calculate the parity. Let's assume we are using even parity:
- Bit 1: 1 + 0 + 1 = 2 (Even) -> LRC Bit 1 = 0
- Bit 2: 0 + 1 + 1 = 2 (Even) -> LRC Bit 2 = 0
- Bit 3: 1 + 0 + 0 = 1 (Odd) -> LRC Bit 3 = 1
- Bit 4: 1 + 1 + 0 = 2 (Even) -> LRC Bit 4 = 0
- Bit 5: 0 + 1 + 0 = 1 (Odd) -> LRC Bit 5 = 1
- Bit 6: 0 + 0 + 1 = 1 (Odd) -> LRC Bit 6 = 1
- Bit 7: 1 + 0 + 1 = 2 (Even) -> LRC Bit 7 = 0
- Bit 8: 0 + 1 + 1 = 2 (Even) -> LRC Bit 8 = 0
Therefore, the LRC byte would be: 00101100
This LRC byte is then appended to the original data.
Advantages and Disadvantages
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Advantage: Simple to implement.
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Disadvantage: Not as robust as more advanced error detection methods like CRC (Cyclic Redundancy Check). It can miss errors if an even number of bits are flipped in the same bit position across multiple bytes.
