My suggestion would be based on the importance/consequences of errors.

If you must be able to detect errors to a very high probability, then the
more complex CRC is possibly the better way to go. If the error rate is
likely to be low anyway, and the consequences of an error are not too bad -
then I'd use a simple checksum - sending (say) the 4 (or less) lsb only.

My guess - based on the small amount of data - 2 or 4 bit checksum.

Richard

> -----Original Message-----
> From: James Cameron [mailto:quozl@US.NETREK.ORG]
> Sent: Tuesday, August 24, 1999 2:33 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [OT] CRCs on short packets
>
>
> Assuming I'm going to be generating between two to eight
> words of twelve
> bits each in a data stream over a remote control UHF link,
> what sort of
> checksum or CRC is appropriate?
>
> I get the impression that calculating a checksum or a CRC on
> such small
> data streams might be ineffective, because of the probabilities
> involved.
>
> For example; sending 24 bits of data followed by a 12 bit arithmetic
> checksum ... the chances of corruption affecting one of the
> 24 bits and
> then also one of the 12 bits of checksum to mask the
> corruption seem to
> be higher.
>
> I'm not exactly sure how to express this ... but is there a concern?
>
> --
> James Cameron
> (quozl@us.netrek.org)
>
> Linux, Firewalls, OpenVMS, Software Engineering, CGI, HTTP,
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>
> "Specialisation is for insects." -- Robert Heinlein.
>