Re: bar code bit encoding.

From: <Adechert_at_aol_dot_com>
Date: Wed Sep 17 2003 - 10:35:06 CDT

I agree, absolutely. The scanning has to be totally reliable.

I will receive my shipment of CueCats (ultra cheap hand-held scanners -- paid
$1 ea on eBay) today or maybe tomorrow. So, we'll be able to start testing
this soon.

Alan D.

In a message dated 9/17/03 3:45:21 AM Pacific Daylight Time, jan@it.uu.se
writes:

> On Tue, 16 Sep 2003, Chris Schaefer wrote:
>
> > At this point our primary goal is to get a working demo running. For
> > this demo it's not super important which encoding we use since we all
> > agree that alot of this code will need to be completely rewritten
> > before we have a real system. So from the perspective of readability
> > during debugging in the demo the encoding technique is not that
> > important. Whatever makes the developer's job easier ( you, I think,
> > right ? )
> >
> > However, I believe there may be one reason to consider an bit
> > encoding technique will different from the 116 bit vector. And this
> > has to do with reliability of scanning in the final demo. We will
> > be using inexpensive scanners. It makes sense to me ( and I have
> > little experience with barcodes other than supermarket shopping) that
> > the shorter the code is, the more likely it will be to read reliably.
> > If this is true, then if we can have with fewer bits than 116 then
> > wouldn't our reliability go up even in the face of using cheap
> > scanners? You have far more experience than me in this area. I'd be
> > curious of your opinions here!!!
> >
>
> Yes, that is exactly what I'm after: to get as small bar code as
> possible, i.e as few digits as possible in the huge decimal number.
> There was some mentioning in another mail of a 60-digit number, and
> I am afraid that may be too long do reliable scanning at the demo.
> Just converting a 116-bit binary to decimal aught to work, as I
> suggested. Otherwise it doesn't matter at all to me how data is
> represented internally. So, either this or some compression would
> be enough as I see it.
>
> When having long messages, there is a tradeoff between using a
> small font size and getting a long bar code. In the first case,
> (cheap) scanner may fail reading the code (can also happen if the
> printer has too low resolution), and in the second case it may be
> hard to follow the entire bar code with a scanner that reads by
> moving it over the bar code. In the demo it would look bad if we
> repeatedly fail to scan a bar code, even if we say that other
> equipment will be used in a real system.
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Received on Tue Sep 30 23:17:06 2003

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