Computer Interfacing
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Why is this the error detection and CORRECTION forum?

I thought CRC was just about detecting errors, not correcting them


 

       Computer Interfacing Forum Index -> Error detection and correction
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saccam
New User



Joined: 03 Apr 2007
Posts: 1


Apr 03, 2007 4:58 am

Just a quick question. I came to this forum via the link on the CRC calculation page of this site. Now this forum is called the error detection and correction forum, but IMHO CRC calculation is only about detection of errors.

Please explain
lammert
Site Admin



Joined: 13 Mar 2007
Posts: 145
Location: Netherlands and Kazakhstan

Apr 14, 2007 1:17 am

saccam, first of all Welcome to the Computer Interfacing forums!

You are right, CRC calculation is about error detection. But without a mechanism to correct the information after an error is detected, error detection wouldn't be of much use. Error correction is not deeply covered yet on the site, but it will be in the near future.

In many communication applications where error detection and correction is needed, the receiver simply rejects an incomming data packet where the CRC or checksum check doesn't match. After a specified timeout time, the sender resends the packet, in the hope it will be received without problems this time. This is for example what happens on a TCP/IP network if a packet gets lost or damaged.

This timeout and resend system is useful with point-to-point connections. But when a data stream is picked up by many receivers without an acknowledge of each received item this simple error detection and resend mechanism doesn't work anymore. Broadcast systems with digital data and multiple receivers are becomming extremely popular, think for example on digital television broadcasting via satellites. Therefore error-correction mechanisms where the datastream contains redundant information to rebuild damaged data when needed are more and more used in digital communications.
Woolmer
New User



Joined: 26 Mar 2015
Posts: 1


Mar 26, 2015 10:42 am

I needed the CRC-CCITT-algorithm for checking of Digital Audio "Dynamic Labels"
in a Python program. Other algos should be as easy to copy from lib_crc.




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kaleem

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