Barcode Symbologies
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From: JosephKK on 3 Jun 2010 01:32 On Mon, 24 May 2010 17:32:19 -0700, D Yuniskis <not.going.to.be(a)seen.com> wrote: >Hi Tom, > >tlbs101 wrote: >> On May 24, 3:06 pm, tlbs101 <tlbs...(a)excite.com> wrote: >>> On May 24, 9:36 am, D Yuniskis <not.going.to...(a)seen.com> wrote: >>> >>>> I need to pick a barcode symbology that is unlinkey to be >>>> encountered in day-to-day items to minimize conflicts. E.g., >>>> UPC is non-starter. >>>> I only need 8 decimal digits so no need for the more complex >>>> codes. I prefer a 2 dimensional code as it increases the >>>> available choices for scanners. I'll probably add a few >>>> digits for my own checksum (above and beyond whatever the >>>> code itself supports). So, maybe 10-12 digits, total. >>>> I suspect ABC Codabar is probably the most obscure (at >>>> least the least likely to be encountered *on* something). >>>> I can even get sneaky and print multipart labels to >>>> be even *more* unique. >>>> But, I'd be open to other suggestions. [I can't roll my own >>>> code as I want to use COTS scanners.] >>>> Thanks! >>>> --don >>> I used code 93 on a military project, 16 years ago. 93 is linear, >>> not 2-D, but there were many scanners available at the time that we > >Yes, 2D was a typo on my part (OTOH, a 2D code would be far >less likely to give a false positive owing to its relative >scarcity -- at least some of them) > >>> (the team) could use. The database was written in FoxPro (not my >>> choice -- lol). > ><grin> I used Paradox for my first database. I've since moved >everything to PostgreSQL. Much more robust, capable and >extensible! > >> Or... just buy a scanner that supports multiple codes and let the >> scanner figure it out. > >The problem isn't the scanner -- as most scanners can be >configured to support a variety of codes. > >Rather, the problem is ensuring that the scanner doesn't >"hit" on a label that isn't "mine". I think you are barking up the wrong tree here, let the scanner spit out lots of invalid for you codes and you sort them out. It is not like they are spitting hundreds of codes per second. And use any 2D code, then your subset acceptable code space can have huge Hamming distances. Plus there is enough internal code space to put internal ECC in. > >For (ridiculous) example, if I adopt UPC as the symbology, then >there will be lots of "false positives" that I'll have to >worry about as so many products carry UPC labels -- I can't >prevent UPC labels from being in the facility! > >This is true of many symbologies. So, my question was to >try to identify a symbology that is so *infrequently* used >that it would be unlikely to "hit" on a label using that >symbology that wasn't placed there by *me*. > >If I use a proprietary scanner and/or code, I can do this >quite well (design a code that is incompatible with existing >codes). But, that should be largely unnecessary if I exercise >care in choosing an appropriate symbology as "mine". > >I can do this in certain special cases but not without >constraining the "grammar" that defines valid symbols too >much. > >So far, it seems like Codabar fits the bill in terms of >being recognizable by OTS scanners, rare enough that it is >unlikely to "pop up" out of pure coincidence *and* tweakable >enough that I can further minimize the chance of false positives >by "abusing" certain features of the code. :-/ > >I'll configure the scanner to tag the data with the code >used and parse that in addition to the data. I.e., if the >data isn't in the expected symbology, then it can't be >"one of my labels".
From: JosephKK on 3 Jun 2010 01:34 On Mon, 24 May 2010 18:30:15 -0700, D Yuniskis <not.going.to.be(a)seen.com> wrote: >Greegor wrote: > >>> I'll configure the scanner to tag the data with the code >>> used and parse that in addition to the data. I.e., if the >>> data isn't in the expected symbology, then it can't be >>> "one of my labels". >> >> Gonna use a Zebra printer? >> >> http://www.zebra.com/id/zebra/na/en/index/products/printers/industrial_commercial/zm400.html > >No. Just print using a laser printer. Print sheets of consecutive >labels. Peel label off, slap onto "whatever". Describe that >"whatever". Move on to the next label. > >(there are some cases where you print a specific label but those >are exceptions -- old label was damaged, etc.) Yep, and there are label printers for doing just that.
From: D Yuniskis on 3 Jun 2010 14:08
Hi Joseph, JosephKK wrote: >> No. Just print using a laser printer. Print sheets of consecutive >> labels. Peel label off, slap onto "whatever". Describe that >> "whatever". Move on to the next label. >> >> (there are some cases where you print a specific label but those >> are exceptions -- old label was damaged, etc.) > > Yep, and there are label printers for doing just that. The problem with those is they allow you to print *any* label "at will" (i.e., without the "system" being aware of the label being issued). They also tend to be thermal (dye transfer) so supplies are more costly. (I've a pile of portable and small desktop thermal label printers getting ready for the recycle bin) As well as the hassle of recharging batteries, etc. And, you need "another" general purpose printer to print your "non barcode" items (i.e., now you have to stock supplies for two different printers). For non-contact scanners at reduced density, easier to use a conventional printer to do that "double duty". |