Re: cyclic redundancy check 4-bit



Dave Hansen wrote:


Any standard implementation?
I need to send 4-bit messages over a very slow and noisy link, I
cannot afford 8-bit crc.
thank you.

The Hamming code 7.4 or 8.4 is what you need.


Well, maybe.

But if the link is very slow, or the noise is bursty, a single-bit ECC
code that doubles the required bandwidth isn't going to help him much.
Then again, a 4-bit CRC isn't going to help much more than a simple
checksum, either...

The Hamming code is a perfect code; no other scheme can have better performance with the same number of data and redundancy bits.

If Hamming 8.4 will be used for the error detection, it will detect all possible combinations of up to three errors, and all error bursts with the length of up to 4 bits.


Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com
.

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