Appendix K
Operator
’s Guide
RJS, Minneapolis, MN
002-7858
56
Scanners and verifiers perceive the narrower bars and spaces to have less intensity than wider
bars and spaces; the comparison of this diminished intensity of narrow elements to wide ele-
ments is called modulation. This condition is affected by aperture size.
Note: Since
“ink spread” will reduce the width and intensity of single module space within a symbol, this
is one thing to check in seeking to correct a low modulation grade
Module
The narrowest expected bar or space width.
Moving Beam Scanner
A laser device that dynamically searches for a bar code pattern by sweeping a moving optical
beam through a field of view.
N (wide to narrow ratio)
In symbologies with two element widths, the wide to narrow ratio of elements is calculated by
summing the average wide bar width and average wide space width and dividing the sum by 2
times Z. Inter-character gaps, if applicable, are not included.
N = (avg.wide bar + avg. wide space) / (2*Z)
Nanometer (nm)
A unit of measure used to define the wavelength of light, equal to 10-9 meter.
Nominal
The intended value for a specific parameter. Tolerances are generally specified as positive and
negative deviations from this value.
No-Read (Non-read, Non-scan)
The absence of data at the scanner output after an attempted scan because of no code, defec-
tive
code or operator error.
Nominal Size
The target size for a specific element or group of elements.
Numeric
A character set that contains only numbers.
Omni-directional
The ability to read a bar code symbol from any angle as long as the bar code passes across the
scanner window.
Opacity
The property of a material that minimizes the show-through of printing from the back side or the
next sheet.
Overhead
The number of characters in a symbol required for start, stop and checking.
Over-laminate
A coating or material adhered to the scanning surface of a bar code symbol.