Communications Blockset™

CRC-N Syndrome Detector

Detect errors in input data frames according to selected CRC method

Library

CRC sublibrary of Error Detection and Correction

Description

The CRC-N Syndrome Detector block computes checksums for its entire input frame. The block's second output is a vector whose size is the number of checksums, and whose entries are 0 if the checksum computation yields a zero value, and 1 otherwise. The block's first output is the set of message words with the checksums removed.

The CRC-N Syndrome Detector block is a simplified version of the General CRC Syndrome Detector 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 dialog. N is the degree of the generator polynomial. The reference page for the CRC-N Generator block contains a list of the options for the generator polynomial.

The parameter settings for the CRC-N Syndrome Detector block should match those of the CRC-N Generator block.

You specify the initial state of the internal shift register by the Initial states parameter. 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 Syndrome Detector block.

This block supports double and boolean data types. The output data type is inherited from the input.

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.

Algorithm

For a description of the CRC algorithm as implemented by this block, see Cyclic Redundancy Check Coding in Communications Blockset™ User's Guide.

References

[1] Sklar, Bernard. Digital Communications: Fundamentals and Applications. Englewood Cliffs, N.J., Prentice-Hall, 1988.

[2] Wicker, Stephen B., Error Control Systems for Digital Communication and Storage, Upper Saddle River, N.J., Prentice Hall, 1995.

Pair Block

CRC-N Generator