User manual

HS-51/HS-51X Wireless Handheld Reader User Manual A-21
Appendices
Appendix G — Glossary of Terms
AGC — See Automatic Gain Control.
Ambient Light — Light which is present in the environment of the front end of a
reader
and generated from outside sources. This light, unless used for actual illumination,
will be
treated as background noise by the reader.
Automatic Gain Control (AGC) — Adjustment to signal strength that seeks to maintain a
constant level regardless of the distance between a reader and symbol.
Baud Rate — The number of discrete signal events per second; bits per second.
Check Character — A Modulus 43 or Modulus 10 character that is added to encoded
symbol data for additional data integrity.
Connector — A plug or socket on a device or cable providing in/out connectivity for various
circuits and pins.
Decode — A Good Read. The successful interpretation and output of the information
encoded in a symbol.
Default — Restores ROM or flash settings and initializes serial commands.
Delimited — A delimited command or field is bracketed by predefined characters.
Decode Rate — The number of good reads per second ahieved by a reader.
Depth-of-Field — The in-focus range of a reader. Measured from the distance behind an
object to the distance in front of the object with all objects appearing in focus.
End of Read Cycle — The time or condition at which the reader stops expecting symbol
information to decode.
Firmware — Software hard-coded in non-volatile memory (ROM), and closely tied to
specific pieces of hardware.
Fixed Symbol Length — Increases data integrity by ensuring that only a symbol length
will be accepted.
Focal Distance — In optics, the distance from the lens to the focal plane.
Focal Plane — Usually found at the image sensor, it is a plane perpendicular to the lens
axis at the point of focus (–).
Focus — Any given point in an image at which light converges; the focal point.
Good Read — A decode. The successful scanning and decoding of the information
encoded in a bar code symbol.
Host — A computer or other device that is used to execute commands and process data
and discrete signals.
Image Sensor — A device that converts a visual image to an electrical signal; a CMOS,
for example.
Initialize — Implement serial configuration commands into the reader’s active memory.
Input — A channel or communications line. Decoded data or a discrete signal that is
received by a device.
LED (Light-Emitting Diode) — A device that emits light when conducting current.
Lens — A transparent piece of material with curved surfaces which either converge or
diverge light rays.