Question

Consider the message 110010 is represented by the polynomial generator polynomial g(x) = 13 + x211.+l4.M(x) = 15 + *4 +x and the calculate the crc.

Answer 1

The General CRC Generator block generates cyclic redundancy code (CRC) bits for each input data frame and appends them to the frame. This block accepts a binary column vector input signal.

You specify the generator polynomial for the CRC algorithm using the Generator polynomial parameter. This block is general in the sense that the degree of the polynomial does not need to be a power of two. You represent the polynomial in one of these ways:

As a polynomial character vector such as 'x^3 + x^2 + 1'.

As a binary row vector containing the coefficients in descending order of powers. For example, [1 1 0 1] represents the polynomial x3 + x2 + 1.

As an integer row vector containing the powers of nonzero terms in the polynomial, in descending order. For example, [3 2 0] represents the polynomial x3 + x2 + 1.

You specify the initial state of the internal shift register by the Initial states parameter. The Initial states parameter is either a scalar or a binary row vector of length equal to the degree of the generator polynomial. A scalar value is expanded to a row vector of length equal to the degree of the generator polynomial. For example, the default initial state of [0] is expanded to a row vector of all zeros.

You specify the number of checksums that the block calculates for each input frame by the Checksums per frame parameter. The Checksums per frame value must evenly divide the size of the input frame. If the value of Checksums per frame is k, the block does the following:

Divides each input frame into k subframes of equal size

Prefixes the Initial states vector to each of the k subframes

Applies the CRC algorithm to each augmented subframe

Appends the resulting checksums at the end of each subframe

Outputs concatenated subframes

If the size of the input frame is m and the degree of the generator polynomial is r, the output frame has size m + k * r.

This block supports double and boolean data types. The block inherits the output data type from the input signal.