CRC-N Generator (Communications Blockset)

Generate cyclic redundancy check (CRC) bits, according to the selected CRC method, and append them to input data frames

Library

CRC sublibrary of Error Detection and Correction

Description

The CRC-N Generator block generates cyclic redundancy code (CRC) bits for each input data frame and appends them to the end of the frame. The CRC-N Generator block is a simplified version of the General CRC Generator block. With the CRC-N Generator block, you can select the generator polynomial for the CRC algorithm from a list of commonly used polynomials, given in the CRC-N method field in the block's mask. The value of N is degree of the generator polynomial. The table below lists the options for the generator polynomial.

CRC Method
Generator Polynomial
Number of Bits

CRC-32
x³²+x²⁶+x²³+x²²+x¹⁶+x¹²+x¹¹+x¹⁰+x⁸+x⁷+x⁵+x⁴+x²+x+1
32

CRC-24
x²⁴+x²³+x¹⁴+x¹²+x⁸+1
24

CRC-16
x¹⁶+x¹⁵+x²+1
16

Reversed CRC-16
x¹⁶+x¹⁴+x+1
16

CRC-8
x⁸+x⁷+x⁶+x⁴+x²+1
8

CRC-4
x⁴+x³+x²+x+1
4

CRC Method	Generator Polynomial	Number of Bits
CRC-32	x³²+x²⁶+x²³+x²²+x¹⁶+x¹²+x¹¹+x¹⁰+x⁸+x⁷+x⁵+x⁴+x²+x+1	32
CRC-24	x²⁴+x²³+x¹⁴+x¹²+x⁸+1	24
CRC-16	x¹⁶+x¹⁵+x²+1	16
Reversed CRC-16	x¹⁶+x¹⁴+x+1	16
CRC-8	x⁸+x⁷+x⁶+x⁴+x²+1	8
CRC-4	x⁴+x³+x²+x+1	4

For a more detailed description of the CRC algorithm, see the section "Cyclic Redundancy Check Coding."

You specify the initial state of the internal shift register by the Initial states parameter in block's mask. You specify the number of checksums that the block calculates for each input frame by the Checksums per frame parameter. For more detailed information, see the reference page for the General CRC Generator block.

Signal Attributes

The General CRC Generator block has one input port and one output port. Both ports allow frame based binary column vectors only.

Dialog Box

CRC-N method: The generator polynomial for the CRC algorithm.
Initial states: A binary scalar or a binary row vector of length equal to the degree of the generator polynomial, specifying the initial state of the internal shift register.
Checksums per frame: A positive integer specifying the number of checksums the block calculates for each input frame.

Pair Block

CRC-N Syndrome Detector

CPM Modulator Passband CRC-N Syndrome Detector