Specifications

120 VISTA AT A GLANCE V5 - FOR MORE INFORMATION VISIT: V I S T A - C C T V. C O M / I P
GLOSSARY OF TERMS
100BASE-T - A high-speed version of Ethernet (IEEE 802.3). Also called
Fast Ethernet standard, 100BASE-T transmits at 100 Mbps.
2CIF (Common Intermediate Format) - 2CIF refers to the analogue
video resolution 704x288 pixels. Also see Resolution.
2D-DNR - applied to the static part of the camera image, it reduces
digital noise created by AGC in low light conditions (grainy effect).
3D-DNR - applied to the moving part of the camera image, it reduces
digital noise created by AGC in low light conditions (grainy effect).
4CIF (Common Intermediate Format) - 4CIF refers to the analogue
video resolution 704x576 pixels. Also see Resolution.
ACPO - Association of Chief Police Officers.
Activity Detection - A feature that uses video motion detection
techniques to improve the camera update times. It also gives a relay
closure.
ADSL (Asymmetrical Digital Subscriber Line) - A telephone line with
uneven transmission rates; half the transmission can attain speeds up
to 640kbps; the other half can attain speeds of 2.048Mbps or greater in
the opposite direction.
AGC (Automatic Gain Control) - An electronic circuit that tries to keep
signals at a constant level; more useful in cameras at low light levels.
The higher the number the better, typical values 12 - 20dB i.e. a gain of
approx 4x - 10x.
Ah (Ampere Hours) - E.g. 1A for 6 hours = 6Ah. Always de-rate the
battery capacity by 66%.
AI (Auto Iris) - An electronic circuit fitted to the iris of a lens to help
compensate for large changes in light levels.
Alarm Bypass Relay - A relay in the controller that is used to shunt
or bypass the door alarm contacts of a central alarm system to allow
authorised access without causing an alarm.
Alarming - The ability of CCTV equipment to respond to an input signal,
normally a simple switch closure. The response varies depending on
equipment type, most common is for switcher to ‘hold’ on the camera
corresponding to the alarm input.
ALC (Automatic Level Control) - On AI lenses, also known as the peak/
average control. Adjusting this control allows the auto iris circuitry to
either take bright spots more into consideration (peak), bringing out
detail in bright areas, or less into consideration (average) bringing out
detail in shadows.
Ambient Light Level - Background or general light level of a given area.
Analogue - A signal in which any level is represented by a directly
proportional voltage not digital.
Angle of View - This is what alters (not the focal length) when you use
a lens designed for one format on another format. It decreases with
format size.
Aperture - The ‘opening’ of a lens, a measure of its light gathering
capability. Relative Aperture is a ratio between its focal length and
effective aperture, measured in F numbers, generally the lower the
better.
Archive - Long-term off-line storage. In digital systems, pictures are
generally archived onto some form of hard disk, magnetic tape, floppy
disk or DAT cartridge, CD-ROM, DVD or flash card.
ARC (Alarm Receiving Centre) - A secure location where signals from
alarm systems are monitored 24 hours a day.
ARC (Alarm Receiving Centre) - This protocol is used to associate an IP
address to a hardware MAC address.
Aspect Ratio - The ratio of the picture frame width to the picture
frame height in standard TV systems. It is 4 units horizontal over 3 units
vertical.
Aspherical Lens - A lens designed with a non spherical shape so that
it refracts the light passing through it to either lower the lens aperture
so that it passes more light or decrease barrel distortion on wide angle
lenses.
ATW (Auto Tracing White) - Automatically adjusts the white balance in
response to varying light conditions.
Auto-terminating - Feature whereby the equipment automatically
selects the correct termination depending on whether the video output
BNC is connected.
Auto White Balance - Feature on colour cameras whereby the camera
constantly monitors the light and adjusts its colour to maintain white
areas.
Back Focus - The mechanical aligning of the imaging device with the
focal point of the lens. Most important on zoom lenses to ensure the
image stays in focus throughout the zoom range.
Balanced Signal - Method of transmitting video, usually over twisted
pair cable, that consists of two equal but opposite signals being sent
down two conductors.
Balun (Balanced Unbalanced) - A device that connects a balanced line,
such as twisted pair, to an unbalanced line, such as coax cable.
Bandwidth - The range of frequencies available for signalling the
difference between the highest and lowest frequencies of a band,
measured in Hertz.
Baud Rate - Unit of signalling speed. The speed in baud is the number
of line changes (in frequency, amplitude, etc.) or events per second. At
low speeds, each event represents only one bit condition, and baud rate
equals bps. As speed increases, each event represents more than one bit
and baud rate does not truly equal bps.
Binary - A base 2 numbering system using the two digits 0 and 1 (as
opposed to ten digits [0-9] in the decimal system). In computer systems,
the binary digits are represented by two different voltages or currents,
one corresponding to zero and another corresponding to one. Positive
logic uses a positive voltage to represent binary 1 and zero volts to
represent binary 0.
Bit (Binary Digit) - The smallest unit of information in a binary system. A
one or zero condition.
Black Level - The level on a video signal, just above the sync pulses,
where black portions of the picture are represented.
Blanking (Field and Line Flyback Blanking) - The operation of turning
off the monitor display or pick-up device during sync pulses to avoid thin
white lines appearing on the picture.
BLC (Back Light Compensation) - A feature of modern CCD cameras
which electronically compensates for high background lighting to give
detail which would normally be silhouetted.