Symbol Series 3100 Product Reference Manual page 68

Series 3100/3500 Product Reference Guide
Range
Any scanning device decodes well over a particular working range — minimum and
maximum distances from the bar code. This range varies according to bar code density
and scanning device optics.
Scanning within range brings quick and constant decodes; scanning too close or too far
away prevents decodes. You need to find the right working range for the bar codes you
are scanning. The best general advice is:
• The larger the symbol, the farther away you should hold the scanner.
• Move the scanner closer for symbols with bars that are close together.
• Start scanning at a distance from the bar code — not from direct contact. If the bar
code does not readily decode, move the scanner in closer.
However, the situation is complicated by the availability of multiple integrated
scanning elements, some with specialized capabilities like long-range or 2-D decode
capability. The best way to specify appropriate working range per bar code density is
through a chart called a decode zone for each scan module. A decode zone simply plots
working range as a function of minimum element widths of bar code symbols.
Decode zones for available integrated 1-D scan elements follow:
4-22