Term A:

AC Adapter:
Alternating Current Adapter; when plugged to AC Power (usually 117VAC/60Hz in the United States) it produces 12VDC, 24VAC or others. "UL Listed" and "Regulated" recommended. It is also called Power Transformer.

AC Power:
Alternating Current Power. In the United States, the standard AC Power is single-phase 117VAC/60Hz and is provided from power outlets in the house. 24V AC power can be produced from an AC Adapter.

AGC (Automatic Gain Control):
Automatically adjusts the video quality in low light condition.

Alarm Sensor:
Like Video Motion Detector, detects changes of motion to produce an alarm.

ALC (Automatic Light 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. Select this mode when an auto-iris lens is used.

A procedure or formula for solving a problem.

Analogue (Analog):
Continuously variable numerical values such as voltage, current, etc.(The CCD camera produces analogue video signals.

Angle of View:
The scene angle that a video camera lens can show on the monitor, like Diagonal Angle, Horizontal Angle and Vertical Angle, usually described in degree.

American National Standards Institute. This organization is responsible for approving U.S. standards in many areas, including computers and communications.

The light gathering area of a lens, controlled by the iris.

Address Resolution Protocol; for mapping an IP address to a physical machine address.

American (National) Standard Code for Information Interchange. A standard character-to-number encoding widely used in the computer industry.

American Society for Industrial Security.

Aspect Ratio:
The ratio of the vertical to the horizontal image size; 3:4 is the NTSC standard.

Aspherical Lens:
A lens designed with a non spherical shape so that it passes more lights or decreases barrel distortion on wide angle lenses.

A decrease or loss in a signal, usually measured in decibels.

Auto-focus Lens:
Automatically adjusts the lens focus from surrounding scene and keeps a moving object in focus.

Automatic Gain Control (AGC):
Automatically adjusts the video quality in low light condition.

Automatic Iris (Auto-iris):
A diaphragm device in the lens that adjusts to light level changes. The iris diaphragm opens or closes the aperture to control the amount of lights coming through the lens.

Automatic Level Control (ALC):
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.

Auto Terminating:
Automatically select the correct termination depending on whether the video output is connected.

Auto White Balance (AWB):
Automatically adjusts a color camera's color to maintain white areas.

Access Card:
An access control identification device assigned to an individual to give that individual access rights to an access control system. Typically, it is the size of a credit card. Each card has a unique identification code. That identification code is used by a controller to determine through which doors and at what times cardholders may be granted access to a secure area.

Access Code:
Numeric or alphanumeric data which, when entered correctly, authorizes entry into a secure area.

Access Control :
A general term describing the control, management, and monitoring of the entrance and exit of people through secure areas.

Access Control Card:
An identification card with encoded information that, when presented to a card reader, identifies the cardholder to an access control system, allowing that system to determine the cardholder's entrance and exit rights.

Access Control System:
An interconnected set of controllers, managing the entrance and exit of people through secure areas.

Access Group:
A superset of information including Time zones and secured Doors that is applied to cardholders. This information defines at what time-of-day and through which doors cardholders are granted access.

Access Mode:
The condition in which all access parameters have been met, allowing an access control system to grant access.

Access Point:
The point of entry into a secure area. This point is typically managed by a controller using some combination of a card reader, an electric door lock, gate, turnstile, or similar device.

Access Parameters:
Programmed information that define the conditions that must be met to grant access. Such parameters may include access codes, access groups, authorization levels, or Timezones.

Access Request:
The act of presenting the information necessary to verify a person's identity.

Acquired Data:
The data collected from an event that is used to make a decision, or is saved for future analysis.

Active Card:
A type of access control card that is dependent upon a card reader to provide the power necessary to allow the card to transmit its data.

A manually operated or automatically controlled switch or sensor which initiates a signal that can be processed by an access control system.

Alarm Annunciation:
The act of announcing that an alarm event has occurred. Annunciation can be done by an audible alarm, warning lamp or LED, or a pop-up window or message (in the case of alarm monitoring via computer software).

Alarm Enable:
The ability to physically or electronically make an alarm input accessible to an access control system.

Alarm Relay Output:
A relay on the controller that changes its state upon command by the controller. Often the alarm relay output activates an audible alarm used to annunciate a door alarm.

American Wire Gauge (AWG):
A standard for designating wire dimensions and specifications.

Anti-Pass back (APB):
A method for providing one-card, one-way access into and then out of a secure area. It prevents someone from using a card to enter a secure area and then passing that card back to someone else to enter that same area.

Audit Trail:
A sequential record that accounts for all the activities of an access control system. This record allows for the analysis of events over a given time period.

Authorization Level:
A security rating that must be met before access to a secure area is granted.

Auxiliary Code:
A secondary code (often used on a temporary basis) that can be used for granting access or allowing access control system operation without revealing a primary code. See Primary Code.

Auxiliary RTE:
A second input source that informs the controller that someone has requested to exit from a secure area. See Request to Exit.