V
All contents are Copyright © 1992–2007 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information.
Page
V
Design Guide
Appendix B: Glossary
A
Alert
A message sent to security personnel indicating the location and nature of an
emergency or threat.
Attenuation
A decrease or loss of signal. Within a fiber or coaxial-cabled surveillance system, this
causes degradation in the video image (e.g. jitter, noise, loss of signal).
C
Camera
An optical device capable of viewing a given area and translating that view into an
electronic signal.
Central Station
A remote location that is designed to monitor signals from physical security systems.
Channel
A single video signal.
Closed-Circuit Television (CCTV)
A television system in which signals are distributed via cables to a closed network of
monitors. This system is most often used for security surveillance in small, closed areas
like buildings or parking garages.
Coaxial Cable
(aka, Coax). A type of cable that is capable of passing a range of frequencies with low
loss. It consists of a hollow metallic shield in which one or more center conductors are
put in place and isolated from one another and from the shield.
Common Intermediate Format
(CIF)
The term CIF is used to mean specific video resolution: 352x288 in PAL 352x240 in
NTSC. CIF is 1/4th of "full resolution" TV, also called D1
Console (CCTV)
The part of a monitoring station an operator uses to control surveillance cameras.
Usually consists of a joystick for PTZ control and a set of numbered buttons allowing
the operator to switch cameras displayed on an attached monitor. It may also refer to
the entire structure at a monitoring station that houses the keyboards, joysticks,
monitors, phones, etc. for controlling the physical security system.
Contrast
The ratio of light to dark portions of a video image.
D
Day and Night
Refers to a video camera’s ability to provide images in both lighted and dark conditions
by changing the imaging format from color to black-and-white, respectively.
Decoder
A hardware or software device that employs a codec to translate a signal from its digital
form into an analog output for display on a monitor.
Depth of Field
The distance between two objects, front to back, which is in focus in a televised scene.
With a greater depth of field, more of the scene, near to far, is in focus.
Digital PTZ
(aka, ePTZ). The capability to virtually pan-tilt-zoom within a digital image. The feature
does not require the ability to mechanically move a camera or its focus. Currently an
emerging feature of megapixel cameras.
Digital Video Recorder (DVR)
Digital Video Recorder is the industry standard term applied to PC-based or embedded
systems that encode and record video images to a computer hard drive. DVRs provide
a quicker method of retrieving the recorded information unlike media such as VHS
tapes and other equipment that stores information in a sequential manner. DVRs are
often integrated into enterprise networks through a single Ethernet interface yet they
terminate multiple analog cameras, typically four, eight or sixteen. (See also
Network
Video Recorder
.)
Dome Camera
A video imaging device contained within a demisphere. Generally supports the ability to
change its focus (i.e. camera PTZ inside the dome) within the field-of-view allowable by
the dome itself.
E
Encoder
A hardware or software device that employs a codec to translate an analog video signal
into a digital form.
F
Field of View (FOV)
A camera’s area of focus (i.e. what it can see).
Frame
The total area of the picture that is scanned. With interlaced video, the frame is
comprised of two fields.
Frame Rate
See
Frames Per Second
.
Frames Per Second (FPS)
A measure of a camera’s rate of output of single snapshots. Also known as images per
second and frame rate.