What is Parity ?
Parity is a bit in form of 0 and 1 and use for detect the errors in signal. It only detects single bit not more than single bit.
What is Parity Bit ?
It is a single bit or extra bit send with original data and it tell total number of 1's present in the signal. We send a bit stream and also an extra bit, it tells total number of 1's in transmitted signal.
Types of Parity :
- Even Parity : In this each set of transmitted bits has an even number of bits. If the total number of ones in the data plus the parity bit is an even number of ones, it is called even parity.
- Odd Parity : In this each set of transmitted bits has an odd number of bits. If the total number of ones in the data plus the parity bit is an odd number of ones, it is called odd parity.
What is an error ?
- Error is a condition when the output information does not match with the input information.
- During transmission, digital signals suffer from noise that can introduce errors in the binary bits travelling from one system to other.
- That means a 0 bit may change to 1 or a 1 bit may change to 0.
How to detect errors ?
- Now we are using even parity in this the receiver can detect the presence of an error if the parity of the receiver signal is different from the expected parity.
- That means, if it is known that the parity of the transmitted signal is always going to be "even" and if the received signal has an odd parity, then the receiver can conclude that the received signal is not correct.
- If an error is detected, then the receiver will ignore the received byte and request for retransmission of the same byte to the transmitter.