87
Each bar\space pair consists of one information bit. A zero bit
consists of a narrow bar followed by a wide space, while one bit
consist of a wide bar followed by a narrow bar. The zero bit is one
unit bar followed by a two-unit space and the one bit is a two-
unit bar followed by a one unit space. The primary application for
the MSI Plessey code is marking of retail shelves and subsequent
scanning with portable devices for inventory purposes.
Nominal
The exact (or ideal) intended value for a specifi ed parameter.
Tolerances are specifi ed as positive and negative deviations from
this value.
Nominal Size
Standard size for a bar code symbol. Most UPC/EAN codes can
be used over a range of magnifi cations (e.g., from 0.80 to 2.00 of
nominal).
NOTIS Editing
An option that strips the start and stop characters from a decoded
Codabar symbol.
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 refl ectance factor of the background and RD the refl ectance
factor of the dark bars.
Programming Mode
The state in which a scanner is confi gured 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.
Random Access
Memory (RAM)
Memory devices where any location in memory can be accessed as
quickly as any other location.
Refl ectance
Amount of light returned from an illuminated surface.
Resolution
The narrowest element dimension which can be distinguished by a
particular reading device or printed with a particular device or
method.
RTS
Request to send.
RxD
Received data.
Summary of Contents for Speechmike 6294
Page 79: ...79 Numeric Bar Codes cont d 4 5 6 7 ...
Page 81: ...81 ...
Page 82: ...82 ...
Page 90: ......
Page 91: ......
