How CRC code is calculated & meaning of common divisor?

Asked By lizgriffinn 10 points N/A Posted on - 08/01/2011

How CRC code is calculated? What is mean by a common divisor?

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Answered By James20 5 points N/A #96463

How CRC code is calculated & meaning of common divisor?

Solution:-The CRC code is calculated as is follow.. The common divisor is set by the agreement of both the sender and receiver. When we divide the data by a common divisor, the remainder is termed as CRC code. p;

Common Divisor:- A combination of binary digits, that is set by both sender and receiver by an agreement. Both the receiver and sender have an agreement on it. At the sender's end the data plus some additional or extra bits, is divided by a common divisor and at the receiver's end, common divisor divide data plus the CRC code and if the result becomes zero, then the data is accepted else it is rejected.

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Answered By henjobeth 0 points N/A #96465

How CRC code is calculated & meaning of common divisor?

 

Hi good day,

• I want to share with you, just a little bit of what I know about your question as it talks about the computation of CRC.
• To compute an n-bit binary CRC, line the bits representing the input, in a row and position the (n+1)- bit pattern representing the CRC’s divisor (called a “polynomial”) underneath the left-hand end of the row. Here is the first calculation for computing a 3-bit CRC:
• 11011011101100  < — Input
• 1011                   < — Input     (4 Bits)
• ————–
• 01100011101100 < — result
• If the input bit above the leftmost divisor bit is 0,  do nothing and move the divisor to the right, by one bit. If the input bit above the left most divisor bit is 1, the divisor is exclusive –  Ored into the input (in the other words, the divisor is then shifted one bit to the right, and the process is repeated, until the divisor reaches the right-hand end of the input row.
• Here is the last calculation:
• 0000000000001110 < — result of multiplication calculation
• 1011 < — divisor
• ————–
• 00000000000101 < — remainder (3 bits)
• Since the leftmost divisor bit zeroed every input bit it touched, when this process ends, the only bits in the input row that can be non zero are the n bits in the right-hand, end of the row. These nbits are the remainder of the division step, and will also be the value of the CRC function (unless the chosen CRC specification calls for some post processing).
• This is all I know my friend. I hope you will get the point.

Thank you.

 

Regards;

 

henjobeth

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