Appendix D Decode Zone Decode Zone
The decode zone for the SD Scan Card 3E is shown below. The decode
zone is a function of various symbol characteristics including density, print
contrast, wide-to-narrow ratio, and edge acuity. The minimum element
width (also known as the “X Dimension”, “size” or “symbol density” of a
bar code) is the width in thousandths of an inch (or ‘mils’) of the narrowest
element (bar or space) in the bar code. The figures shown are the typical
scanning distances (Depth of Field) for selected bar code sizes.
For example, the SD Scan Card 3E should be able to scan a 10 mil bar code
when the bar code is positioned between 1.25 and 7.5 inches from the nose
of the scanner.
The maximum readable length of a bar code symbol (Width of Field) at any
given range is also shown. In the example above, the maximum length of a
10 mil bar code scanned at a distance of 7.5 inches is approximately 8
inches including the quiet zone.
36 | APPENDIX D: DECODE ZONE