Cyclic redundancy check, transcription

Cyclic redundancy check, transcription Cyclic redundancy check, transcription

Add an FCS (frame checksequence, frame check sequence) to each data block (called frame) for the transmit/receive unit to compare frames correctly or not

Cyclic redundancy check: CRC (cycli redundancy check)

1. M represents the transmitted data
   
2. K indicates the length of the transmitted data
   
3. N-bit redundancy code, can be obtained with M * 2^n
   
4. The number (N+K) is divided by the divisor P of the length (n+1) Bits agreed between the receiving and transmitting parties, and the remainder (not the mathematical remainder) is calculated.
   
5. This remainder becomes the frame test sequence FCS (frame check sequence)
   

For example
Suppose M = 101001 is the transmitted data, K is the length of the data is 6
Set n = 3
The sequence of the composition is 101001000.
Suppose the divisor P is 1101 (n+1) bit

1101/101001000

Send end frame test sequence FCS generation and robbery means the CRC test is done by the hardware, processing quickly

CRC unresolved transmission problems: frame loss, frame repetition, frame out of sequence

Note: crc32-computes a crc32 polynomial of a string

Cyclic redundancy check, transcription