Long Distance Scanning in Your Distribution Center

By Bob Giammarco, Universal Label Technologies

You have pallet racking and bulk storage in your warehouse and now you want to bring in a warehouse management system using barcoding.  But, how in the world are you going to scan those upper levels and bulk storage areas?  You do remember someone talking about retro-reflective labels and how they can scan from long distances, but do they really work and will they work for you?  The answer to those last questions are yes and yes…well, with a few important caveats to keep in mind.

While, the retro-reflective label material is indeed manufactured to facilitate long distance scans, it is not the material alone that makes that happen.  In order to get that long distance scan, you must have the appropriate scanner AND barcode printed on the label.   Here is why:

THE CORRECT SCANNER

Barcode scanners have come a long way over the years.  Many scanners have engines within them that can scan both long and short range, however, there are still scanners available that can only scan from short ranges.  There is a misconception in the industry that as long as the labels are made using reflective material, then you will be able to scan from long distances.  This just isn’t true.  If your scanners are not engineered to scan from long distances, it is impossible to scan from outside the maximum range regardless of the material used for the labels. 

So, with that being said, if you will be labeling upper level racks or hanging signs above your bulk storage locations, make sure you have the appropriate, long range scanner.

THE CORRECT BARCODE

Now that you have the correct scanner, you should be able to scan your reflective labels from any distance, right?  Not quite.   The scanner and material alone will not allow you to scan from long distances.   You have to have the appropriate barcode as well to get that long distance scan.  To understand what the appropriate barcode is, you first need to know a little about what comprises a barcode.

A barcode is a series of thin and thick black lines and white spaces, configured in such a way that when read by the scanner is deciphered and translated into characters that we recognize (numbers, letters, ASCII, etc).  The thin bar of the barcode is also called the X-dimension.  The X-dimension is measured in thousands of an inch (mils).  This X-dimension determines the size of the thick elements of the barcode as well in the form of a size ratio larger than the X-dimension.   So, if an X-dimension is 10 mils, then the larger lines can be anywhere from 20-30 mils depending on which barcode symbology is being used.   The size of X-dimension is what also dictates how far of a distance you can scan your label from.   It would stand to reason that the thicker the bars, the further away the scanner can read.  Just like the human eye, the larger the print, the further away we can read.

The typical scanner will require an X-dimension of anywhere from 70 mil to 100 mil in order to get a long distance scan from 15’-25’ or further. Most scanners come with a depth of field chart showing you how long they can scan when using the appropriate X-dimension of the barcode.  Review your scanner’s documentation and find this chart to avoid any surprises after you’ve installed your retro-reflective labels.

THE SIDE EFFECT

One very important piece of information to keep in mind when planning for long range scanning is to remember that your barcode is going to be very large and therefore your label needs to be as well.  Many people go into a project of this type thinking they can put their barcodes on any size labels and still get the long distance scan.  This is a common error.  The reality is that depending on how many characters are included in your data string, you may end up with a label that is 15”-20” long because you will need to use a very large X-dimension in conjunction with your data string.  I’ve seen too many people think they are going to get long distance scans by using a 4x6 reflective label and then printing a 20 mil X-dimension in order to make it fit.  IT WON’T WORK!  That is wasted money and when using retro-reflective material you are talking about far more money than your typical label material.

START SCANNING

Ultimately, when you put all these pieces together, you should have the luxury of getting long distance scans in your facility.  However, if one of these components is incorrect (scanner, X-dimension or of course, material), you will be disappointed, frustrated and over budget because you won’t get the type of result you were looking for. 

Here is a review of the things to keep in mind for a successful long distance scanning project:

• Use the appropriate long range scanner
• Maximize the X-dimension of your barcode
• Use the appropriate size label to fit your larger barcode
• Use retro-reflective material