Symbol Technologies MK1000 User Manual

Page 205

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Glossary-7

Glossary

Nominal Size

Standard size for a bar code symbol. Most UPC/EAN codes are used
over a range of magnifications (e.g., from 0.80 to 2.00 of nominal).

Parameter

A variable that can have different values assigned to it.

Percent Decode

The average probability that a single scan of a bar code would result
in a successful decode. In a well-designed bar code scanning system,
that probability should approach near 100%.

Print Contrast
Signal (PCS)

Measurement of the contrast (brightness difference) between the bars
and spaces of a symbol. A minimum PCS value is needed for a bar
code symbol to be scannable. PCS = (RL - RD) / RL, where RL is the
reflectance factor of the background and RD the reflectance factor of
the dark bars.

Programming Mode The state in which a scanner is configured for parameter values. See

SCANNING MODE.

Quiet Zone

A clear space, containing no dark marks, which precedes the start
character of a bar code symbol and follows the stop character.

Reflectance

Amount of light returned from an illuminated surface.

Resolution

The narrowest element dimension which is distinguished by a
particular reading device or printed with a particular device or method.

Scan Area

Area intended to contain a symbol.

Scanner

An electronic device used to scan bar code symbols and produce a
digitized pattern that corresponds to the bars and spaces of the
symbol. Its three main components are:

1. Light source (laser or photoelectric cell) - illuminates a bar code.

2. Photodetector - registers the difference in reflected light (more light
reflected from spaces).

3. Signal conditioning circuit - transforms optical detector output into a
digitized bar pattern.

Scanning Mode

The scanner is energized, programmed, and ready to read a bar code.

Scanning Sequence A method of programming or configuring parameters for a bar code

reading system by scanning bar code menus.

Self-Checking Code A symbology that uses a checking algorithm to detect encoding errors

within the characters of a bar code symbol.

Space

The lighter element of a bar code formed by the background between
bars.

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