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This glossary page is an A-Z of the most common industry terms related to fire, security, access control and CCTV systems. If the word or phrase you are looking for is not found, or you need other help or advice please get in touch.



Advanced Alarm Control: A flexible and sophisticated alarm management subsystem that allows rules to be created that define which input(s) activate one or more outputs. In its most basic form, a rule could define which input(s) should activate which output(s). In a more complex form, a rule can be programmed to take a specific keyboard command (pre-existing or not) and perform a dome function, or any combination of the above.

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. See Key Tag.

Access Code

Numeric or alphanumeric data which, when entered correctly into the keypad of an access control system, 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 the card reader of an access control system identifies the cardholder to an access control system, allowing that system to determine the cardholder’s entrance and exit rights.

Access Control Network

See Access Control System.

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 Timezones 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 Level

See Authorization Level.

Access Mode

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

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 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 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.


Addressable devices are given an individual address so their exact location can be identified. See Analogue Addressable and XPERT Card for more information.

Addressable System

An addressable system is one in which signals from detectors, manual call points or any other devices are individually identified at the control and indicating equipment.

Advanced Diagnostics

Bosch’s combination of built-in On Screen Displays (OSD) and status LEDs that are used to check critical camera parameters such as internal temperature, input voltage levels, and network connectivity. This allows a technician to quickly determine the source of problems and to ensure that the dome is functioning within the correct operating limits.


Automatic Gain Control: The electronics that regulate the gain or amplification of the video signal.

Air Sampling Unit

A device used to detect smoke within ventilation systems.


The state which a device enters when a fire is detected, signalling an emergency.

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 Disable

The ability to physically or electronically make an alarm input unaccessible to an access control system.

Alarm Enable

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

Alarm Mask

The ability to selectively suppress the annunciation of certain alarm conditions, but allowing all other alarm conditions to properly report.

Alarm Receiving Centre (ARC)

When you have an intruder, there’s no point in having an alarm unless you can be confident that someone is instantly aware and ready to act.

That’s why we have our own dedicated Alarm Receiving Centre – to monitor remote alarms. We are there to help 24 hours a day. And that goes all the way – right down to checking that the battery is properly charged. The moment an alarm is sounded, one of our trained operators takes over, calling keyholders or the police, whichever is appropriate.

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.


A range of conventional devices by Apollo that utilises two-wire technology.

To find out more, visit the AlarmSense page.


A text string made up of alphabetic and numeric characters.

American Wire Gauge (AWG)

A standard for designating wire dimensions and specifications.


An analogue signal is one which goes up and down steplessly. Analogue fire detectors are not restricted to two states – alarm/no alarm – as conventional detectors are.

Analogue Addressable

The analogue addressable term used to describe a fire detection system incorporating analogue detectors which are also identified by a number or ‘address’.

Analogue addressable detectors provide location-specific information on the ambient level of smoke, heat or other product of combustion (eg carbon monoxide).

AND Gate

A logic circuit that requires that all inputs must be in a high state (logic 1) to generate a high state output (logic 1).


A device (such as a light or horn) that indicates an event has occurred.


An acronym for American National Standards Institute.

Anti Passback (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.


The size of the opening in the iris, which controls the amount of light that reaches the CCD Sensor. The larger the F-Stop numbers, the less light reaches the sensor.


Address Resolution Protocol: A protocol for mapping MAC and IP addresses.


ASA stands for Advanced Signal Analysis (ASA) technology. ASA technology™ is a patented technology manufactured by Siemens which has the ability to quickly and reliably detect smoke, heat, and carbon monoxide. The intelligence of nine selectable parameter sets means ASA fire detectors are immune to deceptive phenomena, which in turn prevents unnecessary downtimes and costs caused by false alarms.


This is an approval for products designed for use in hazardous areas. See also BASEEFA.

Attended ID Station

A station where a security individual verifies the identity of someone seeking to enter a secure 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.

Authorized Person

A person who has been cleared to enter a secure area.


A technique of boosting the video signal level to produce a full amplitude video signal, even when the scene contrast is less than full range (glare, fog, mist, etc.). The darkest part of the signal is set to black and the lightest part to white, thus increasing the contrast.


Fully integrated, high speed, pan/tilt/zoom camera built into a protective dome housing allowing full and continuous 360° coverage of the scene.


The lens continuously adjusts to the correct focus automatically for the sharpest picture.


The lens iris opening is automatically adjusted to allow the correct illumination of the camera sensor.

Automatic Time Switch

A timer that turns devices on or off at pre-set times.


The camera pans continuously between right and left limit settings.


As the camera tilts through the vertical position, the camera rotates to maintain the correct orientation of the image.


This function records the sequence of movements of the camera’s PTZ for later playback allowing a set pattern to be repeated automatically. This function is often called Guard Tour.


As the camera zooms in to increase the size of objects on the monitor screen, the pan and tilt speeds are reduced so that the relative speed on the screen remains constant for similar joystick control positions.


A patented technology that integrates motion detection into the camera allowing tracking of an object and zooming in to optimize size and perspective.

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.


Auto White Balance: A feature that allows a color camera to automatically adjust its output color to give a natural color, independent of the lighting used.


See American Wire Gauge.



An accessory which provides a high degree of protection against the ingress of water or dust into the back of the detector.

Backward Compatibility

A term used to describe equipment that is compatible with older products. See also ‘forward compatibility’.

Badge Reader

A reader used to read and interpret data encoded in an identification badge. See Card Reader.

Badging Software

Security software that is capable of creating Photo Identification badges.


Short for Balance/Unbalanced. A device that converts a balanced video signal (e.g. as used on twisted pair) line to an unbalanced signal (e.g. as used on coax). In a balanced line both wires are electrically equal. In an unbalanced line one wire has different electrical properties than the other.

Bar Code

A method of encoding information using lines and blank spaces of varying size and thickness to represent alphanumeric characters.

Bar Code Card

An access control card with identification information encoded in Bar Code format.

Bar Code Reader

A reader capable of reading and interpreting cards using bar codes to encode data.

Barium Ferrite Card

An access control card with identification information encoded in the card via magnetic material embedded in the card.

Barium Ferrite Reader

A reader capable of reading and interpreting cards using barium ferrite to encode data.


Apparatus upon which the fire detector is mounted. To find out more about Apollo bases, visit the Bases page.


British Approvals Service for Electronic Equipment in Flammable Atmospheres. This is the approval body, under the HSE, for products designed for use in hazardous areas. See also ATEX.

Batch Programming

A method for processing data or performing tasks in which a number of commands are collected and then processed by a controller all at one time.

Battery Backup

A secondary energy source used to power devices in the event the primary energy source fails. Battery Backup typically provides power for a short period of time, allowing for immediate action, system protection, and system shutdown before the battery reaches a drained state.


The unit of data signal transmission speed, typically expressed in bits per second.


Unit of measure for the speed of data transmission.


A device used to produce a visible indication of an alarm. To find out more about Apollo bases, visit the Beacon page.

Beam Detector

A device incorporating a transmitter (which projects a beam of infra-red light), receiver (which registers the light and produces an electrical signal) and an interface (which processes the signal and generates alarm or fault signals).
Beam detectors are designed to protect large, open spaces.

Bell box

The distinctive SECOM bell box is an external sounder which has a self-contained high output two tone sounder incorporating a strobe light for visual indication. All electronic components are contained within a secure fully tamper proof enclosure.

Bell Transformer

A small transformer used to reduce power line voltage to the level required by low power devices (i.e. card readers)


A communications protocol that allows remote control, configuration, and updates to be performed over the video cable (Coax or Passive UTP).

Bilinx address

The address may be set locally using the Bilinx Configuration Tool for Imaging Devices (CTFID) or remotely using the Fast Address function (see Fast Address).

Binary Coded Decimal (BCD)

The decimal numbers 0 through 9 expressed in a 4-bit binary format.

Biometric Access Control

Access control where the identification process is made through biometric parameters. See Access Control, Biometrics.


A general term for the verification of individuals using unique biological characteristics (i.e. fingerprints, hand geometry, voice analysis, the retinal pattern in the eye).


Pan/Tilt/Zoom protocol for Bosch products.


An abbreviation for “binary digit” in the binary number system. A bit will have the value of either 0 or 1.


Bits per second, the actual data rate.


Back Light Compensation: Selectively amplifies parts of the image to compensate for large contrast differences when only a portion of the image is brightly lit (e.g. a person in a sunlit doorway).

Break Before Make

A type of switch in which one set of contacts open before another set of contacts closes.

Break glass detectors

Break glass detectors are fitted over or next to shop fronts or other vulnerable glazing. They detect the sound of breaking glass, together with the accompanying change in air pressure.

BT redcare GSM

Redcare GSM works on a BT telephone line backed up by the O2 cellular network. This is known as dual path signalling. It gives warning of a line cut and loss of signalling. This is one of the most secure forms of signalling available today.

BT Redcare is more secure than a digital communicator with the added enhancement of alerting the ARC if the line is cut or tampered with. Police guidelines mean that they will not be summoned if the line fails. Instead, the keyholder will be called to investigate for themselves. This device is used for residential and business premises.


1) In power systems, a solid metal or uninsulated wire connector from which a universal type of power or ground connection is made. 2) In computer or data transmission systems, the principal channel through which all major sections communicate.


A group of eight binary data bits.


Cable Category

Application and bandwidth rating system for UTP cabling. Categories 1 through 7 are based on EIA/TIA-568-B standards. Category is typically abbreviated CAT. UTP Category 5, 5e, 6, and 7 are used for Ethernet data cabling applications. Ethernet wiring distances are limited to a maximum of 100 m (328 ft.) when using UTP wiring.

Cable Compensation

A technology that prevents image degradation caused by signal losses when transmitting video over long cable lengths.

Carbon Monoxide (CO) Fire Detector

A device incorporating an electrochemical cell which senses carbon monoxide (CO) but not smoke or any other combustion products. It works by sensing the level of CO in the air.


An identification device assigned to an individual that identifies that individual. Typically, it is the size of a credit card. See Access Card, Key Tag.

Card Access

A type of access control system using encoded cards and card readers to identify cardholders and determine if access may be granted. See Cardholder.

Card Encoder

A device used to encode data onto an access card.

Card Reader

A device that retrieves information stored on an access card and transmits that information to a controller.


An individual who has been assigned an access control card or tag.


Charged Coupled Device: A type of solid state image sensor used in CCTV cameras. The sensor converts light energy into electrical signals.

CCD Format

Indicates the size of the camera sensor used. In general, the larger the sensor, the more sensitive the camera and the better the image quality. The format is quoted in inches, for example 1/4 or 1/3 inch.


Closed Circuit TeleVision: A video system that transmits television signals over a closed (non- broadcast) system.


CompactFlash: Digital storage media – used in computers, digital cameras, and Personal Digital Assistants (PDA) in the form of CF cards.


An additional set of information transferred with a computer program or a data stream that is used to verify the accuracy of the data just transfered.


See Smart Card.


Common Intermediate Format: Video format with 352 × 288/240 pixels.

Circle of Protection

A security plan in which the items to be protected are surrounded by two or more protective zones of increasing size. For example, a bank vault may have the heavy vault door, followed by a controlled access door into the vault area, followed by the bank building with an alarm system.

Circuit Breaker

A switch on an incoming power circuit that opens if abnormal circuit conditions arise (such as an overload or short circuit).

Closed Protocol

A protocol is said to be closed if its mode of operation and timings are not published. Closed protocols mean that all components of a fire detection system must be sourced from the same manufacturer. See also ‘open protocol’.

Color Temperature

A measure of the relative color of illumination. Generally used to specify the color balance correction of a camera to achieve a natural color image.

COM Port

A hardware device that allows a computer to communicate with external devices.


A material that readily allows electricity to flow through it. Most metals are good conductors.

Confirmed light

This is a light programmed to come on as soon as any secondary detection device is triggered. Although not a strict DD:243 requirement, it does help overcome potential health and safety issues.
Once a keyholder is called to attend the premises after one detection device has been triggered, it is reassuring to know that a warning light will let them know if a second device has been triggered, suggesting that an intruder is inside. As a matter of course, SECOM Plc fits a confirmed light at the final exit on every system that requires police response.


A magnetically or electrically controlled connection point that opens or closes to interrupt or allow the flow of current.

Contact Rating

The load rating of a switch, listed by maximum voltage and/or current accepted by the switch.

Continuity Link

The Continuity Link is a feature of the Orbis TimeSaver® Base which enables voltage testing of zone wiring prior to commissioning.

Control & Indicating Equipment (CIE)

Apparatus used to control a fire protection system. Often called a ‘control panel’.

Control Center

A central location in a secure area where access and alarm sub-systems are supervised and security personnel are located.

Control Point

An exit or entry point such as a door, turnstile, or gate, where access is controlled.


A microprocessor based circuit board that manages access to a secure area. The controller receives information that it uses to determine through which doors and at what times cardholders are granted access to secure areas. Based on that information, the controller can lock/unlock doors, sound alarms, and communicate status to a host computer.


The term ‘conventional detector’ is used to describe a two-state fire detector ie normal state and alarm state. In conventional systems, devices are wired into a circuit or ‘zone’ of up to 20 detectors. An alarm is indicated by zone on the fire alarm panel. Generally used on non-addressable systems.


The CSA label on a product signifies that the product has met requirements set by CSA International, and that the product manufacturer is authorized to use the CSA symbol on their products.


Configuration Tool for Imaging Devices: Bosch software used to configure and update cameras and other remote devices over video cable using Bilinx, and to save them for later use.


Composite Video Blanking and Sync: The format of an analog television (picture only) signal before it is combined with a sound signal and modulated onto an RF carrier. Composite video is often designated by the CVBS acronym, meaning any of Color, Video, Blank, and Sync, Composite Video Baseband Signal, Composite Video Burst Signal, or Composite Video with Burst and Sync. It is usually in a standard format such as NTSC, PAL, or SECAM.

Cypher Lock

A digital push-button combination lock.


D Day/Night (IR sensitive)

A camera that has normal color operation in situations where there is sufficient illumination (day conditions), but where the sensitivity can be increased when there is little light available (night conditions). This is achieved by removing the infrared cut filter required for good color rendition. The sensitivity can be further enhanced by integrating a number of frames to improve the signal-to-noise ratio of the camera.

Deckhead Mounting Box

A robust metal or plastic unit which can be used with Series 60 or XP95 devices to protect against the ingress of water or other contaminants through the rear of the base.

Dedicated I/O Point

An input or output that is dedicated to a specific function. Often, dedicated input points can be assigned to initiate tasks such as an Auxiliary RTE, and a dedicated output point can be assigned to initiate tasks such as the annunciation of Door Forced or Door Held Open alarms.

Dedicated Telephone Line

A telephone line directly connecting two points. Also Known As – Lease Line.

Default Shutter

A feature allowing the shutter speed to be set to a fast speed to eliminate motion blur and provide a detailed and clear image of fast-moving objects while there is sufficient light. When light levels fall and other adjustments have been exhausted, the shutter speed reverts to the standard setting to maintain sensitivity.


A device that creates a strong magnetic field that erases data from magnetically encoded media such as magnetic stripe cards.

Degraded Mode

A mode of controller operation that provides a minimal authorization level in the event of controller failure.


A device for discovering the presence of a fire.


Dynamic Host Configuration Protocol: Uses an appropriate server to enable dynamic assignment of an IP address and other configuration parameters to computers on a network (Internet or LAN).

Digital communicator

Digital communicators work a bit like a computer modem. They transmit basic data, such as an alarm from the protected premises. They won’t notify the ARC if the phone line has been cut and can’t send a signal if the line is engaged. They are most commonly used for smaller residential systems.

Digital Image Stabilization

See Image Stabilization

Digital Protocol

A digital protocol comprises a series of binary digits (1’s & 0’s), and is used as a method of communication between electronic devices.


Rail mounted electronic assembly housing, compliant with the German standard DIN 46277.


A high-performance, smart surveillance camera series designed by Bosch utilizing 10 and 15- bit digital video processing.


DirtAlert is a feature of Orbis which uses a flashing yellow LED to show that the drift compensation limit has been reached.

Discovery ®

An advanced range of analogue addressable devices manufactured by Apollo.

Distributed Access Control

Access control systems in which all control decisions are made at the local controllers, independent from a host computer. Local Controller events are uploaded to a host computer periodically for review and storage.


The Bosch Divar digital video recorder (DVR) series are compact, low profile units that combine advanced digital recording and multiplexing.


Dynamic Noise Reduction: A digital video processing technique that measures the noise (image artifacts) in the picture and automatically reduces it.


Domain Name System: A service that stores domain names and translates them into Internet Protocol (IP) addresses.


A generic term for a securable entry way. In many access control applications a “door” may actually be a gate, turnstile, elevator door, or similar device.

Door Forced Alarm

An alarm generated when a door is forced open, opening the door switch contact.

Door Held Open Alarm

An alarm generated when a door is held open beyond the a designated period of time (as programmed by access control software).

Door Held Open Time

The amount of time from when a door is opened before an alarm is generated for the door being opened too long. This is often used to monitor if a door is being propped open following a valid access request.

Door Switch

A switch that reflects the state of the door: if the door is open, the switch is open — if the door is closed, the switch is closed.


Sending information from a host computer to a peripheral device in an access control system.

Drift Compensation

A signal processing algorithm which compensates for detector contamination or environmental conditions and maintains the desired sensitivity level.

Dual Technology Movement Detectors

These detectors combine infra red and microwave detection technologies and both have to be activated to cause an alarm.


This device is another form of dual path signalling. A Paknet radio transceiver transmits the alarm signals and a digital communicator gives warning if there are radio signal problems.


Term used to define the direction of data transmission between two parties. Half-duplex allows data transmission in both directions but not simultaneously. Full-duplex allows simultaneous data transmission.


Forcing a person to provide access to a secure area against that person’s wishes.

Duress Alarm

A device that generates a silent alarm signal in the event a person is experiencing Duress. This device may be a stand alone signalling device or it may be incorporated into a reader.

Duress Code

An alphanumeric code which, when entered into an access control system, alerts the system to a Duress condition.


The DustDefy system is a feature of Orbis which prevents dust ingress while maintaining airflow.

Duty Cycle

The ration of system ON time to system OFF time.


E-Z Fit Slots

These allow the TimeSaver® Base to be fixed in position without removing mounting screws, using a simple sliding action.

Earth Ground

An electrical connection point that brings all electrically neutral lines to the earth’s surface potential (essentially zero potential). A good earth ground helps to protect electrical devices from damage caused by transients such as power surges and lightening strikes, and drains electrical interference from data, communication, and power lines that support these electrical devices. See Ground.

Electric Door Lock

A remotely operated electric locking device. See Electric Strike, Electromagnetic Lock.

Electric Strike

An electric door lock that requires power to be applied to unlock a door.


A general term referring to the electric and magnetic fields associated with the movement of electrons through conductors.

Electromagnetic Interference (EMI)

Excess electromagnetic energy radiated by an electrical device that may affect the operation of other electrical devices.

Electromagnetic Lock

An electric door lock that uses an electromagnet to hold a door closed. See Magnetic Lock.

Embossed Card

An access control card that uses a raised pattern as a means of encoding data.


See Electromagentic Interference.


The process of writing data to a card.

Entrance Delay

See Door Held Open Time.


Camera with environmental protection that allows it to be used outdoors in almost any climate.


An acronym for Erasable Programmable Read Only Memory.


The most commonly used local area network (LAN) access method. Ethernet complies with the IEEE 802.3 standard. The Ethernet standard supports 10 Mbps, 100 Mbps, 1000 Mbps, and 10 Gb (Gigabit) data transmission rates.


An occurrence at a controller (such as unlocking a door, requesting to exit, forcing a door open) that generates a message stored by the controller.

Exit Alarm

A device that indicates (either audibly or silently) that a secure door has been forced opened.

Exit Lock

A push-bar door lock that spans the width of the door, used for emergency exit. An Exit Lock may be connected to an Exit Alarm.

Exit Reader

A reader used to control exiting from a secure area.

Exit Switch

A switch that is used to initiate a Request to Exit. See Request to Exit.



The standard measure of the lens aperture, which is the iris diameter, divided by the focal length of the lens. The lower the maximum aperture (F-Number or F-Stop), the more light that passes through the lens.


See F-Number

Facility Code

Coded data in access control cards that identifies the location of the access control system.

Fail-Safe Door

A fail-safe door is one that if the power should fail at that door, the door will automatically unlock allowing exit and entrance. A fail-safe door ensures people will be able to exit a secure area through that door in the case of an emergency.

Fail-Safe Lockset

A lockset that is normally locked when the power is ON, and automatically unlocks when the power fails. See Fail-Safe Door.

Fail-Secure Door

A fail-secure door is one that if the power should fail at that door, the door will automatically lock and not allow entrance, but will continue to allow exit. A fail-secure door ensures a secure area remains secure regardless of the situation.

Fail-Secure Lockset

A lockset that is normally unlocked when the power is ON, and automatically locks when the power fails. See Fail-Secure Door.

False Alarm

An alarm signal generated without an existing alarm condition.

Fast Address

A system for setting the address of the camera remotely from the control system.


FastTest is a feature of Orbis. It is a maintenance procedure that takes just four seconds to test and confirm that smoke and heat detectors are functioning correctly.

Fiber Optic Transmission

Refers to the transmission of video and data via optical fibers. Optical fibers are thin glass strands that are designed for light wave transmission. Video and data are digitized and transformed into a series of light pulses. There are two primary types of optical fiber; singlemode and multimode. Singlemode fiber is used when large distances must be spanned, typically greater than 2 Km/1.2 miles (see Singlemode). Multimode is typically used to span smaller distances such as the inside of buildings or on small campuses (see Multimode).

Field of View

The measure of the visible area within the camera’s field of view. The larger the focal length, the smaller the field of view. The smaller the focal length, the wider the field of view.

Fingerprint Pattern Area

The identifying characteristics of a fingerprint, consisting of the arches, loops, and whorls in the fingerprint.

Fingerprint Reader

A biometric reader that identifies a person based on the person’s fingerprint pattern.

Fire Alarm Control Panel

Apparatus used to control a fire protection system and often called a ‘control panel’. Usually described in standards as ‘Control and Indicating Equipment’ (CIE).

Fire Detector

A device which senses the combustion products of a fire – such as heat, smoke or carbon monoxide.

Fixed Temperature Detector

A device that incorporates a thermocouple or thermistor to sense temperature change. If a given (fixed) temperature is exceeded, the device goes into alarm mode.

Flame Detector

A device incorporating an infra-red or ultraviolet sensor to detect the radiation emitted by flames.


Fixed compact cameras in surveillance domes with economical, indoor models and high- performance, vandal resistant styles.

Focal Length

The distance from the optical center of the lens to the image of an object located at an infinite distance from the lens. Long focal lengths give a small field of view (e.g. telephoto effect), while short focal lengths give a wide angle view.

Forward Compatibility

A term meaning that equipment is compatible with newer products. See also ‘backward compatibility’.


A single video image.

Frame rate



File Transfer Protocol: Used to transfer files between computers on a network, such as the Internet.

Full duplex

Simultaneous data transmission in both directions (sending and receiving); (see Duplex).



Typically, a door that is outdoors.

Gateway Address

A node on a network that serves as an entrance to another network.


GigaBit Interface Converter: Applied in network technology to render interfaces flexible, i.e. converting an electrical interface into an optical interface. This enables flexible operation of an interface as a Gigabit Ethernet via twisted-pair cables or fiber optic cables.

General Protection Fault

An operating system fault that occurs whenever a program executes a command that the operating system considers dangerous to the operating system. When a GPF is generated, the program that generated the GPF is closed and control is returned to the operating system.

Global Unlock

A normally-open input that, when closed, generates a signal that unlocks all doors in the access control system.


Group of Pictures: In MPEG video encoding, a group of pictures, or GoP, specifies the order in which intra-frames and inter-frames are arranged.


1) An electrical connection with a ground potential point. 2) An electrical connection to a circuit’s zero voltage reference point. See Earth Ground.

Guard Tour

Allows recorded tours with a combined duration of 15 minutes. Recorded tours consist of control commands and can be played back as needed. All camera position information is stored for maximum flexibility (including pan, tilt, zoom, etc.).


Hand Geometry

A biometric access control technology that verifies a person’s identity by using the variations in hand size, finger length, and finger thickness.

Heat Detector

A device that uses a thermistor to detect abnormally high temperature changes.

Historical Log

A chronological record of events.

Host Computer

The central controlling computer from which access control software applications are run.


Hypertext Transfer Protocol: Protocol for transmitting data over a network.


Hypertext Transfer Protocol Secure: Encrypts and authenticates communication between Web server and browser.

Hybrid Streaming

The ability to simultaneously stream IP video across a local or wide area network, and CVBS video via coaxial or fiber optic cabling.



Internet Control Message Protocol: One of the core protocols of the Internet protocol suite. It is chiefly used by networked computers’ operating systems to send error messages indicating, for instance, that a requested service is not available or that a host or router could not be reached.


Identification: A machine-readable character string.


The act of recognizing one person as being unique from all other people.

Identification Card

A card that stores the information necessary to verify the identity of the cardholder.


Institute of Electrical and Electronics Engineers: The world’s leading professional association for the advancement of technology.

IEEE 802.1x

The IEEE 802.1x standard provides a general method for authentication and authorization in IEEE-802 networks. Authentication is carried out via the authenticator, which checks the transmitted authentication information using an authentication server (see RADIUS server) and approves or denies access to the offered services (LAN, VLAN, or WLAN) accordingly.


Internet Group Management Protocol: A communications protocol used to manage the membership of Internet Protocol multicast groups.

Image Stabilization

An algorithm that virtually eliminates camera shake in both the vertical and horizontal axes, resulting in exceptional image clarity.

Infrared beams

A transmitter projects an infra red light beam to a receiver unit. Interrupting the beam triggers an alarm. In hostile environments, dual or twin beam units are used, where both beams have to be interrupted. They can be used inside or outside.

Infrared Illumination

Electromagnetic radiation (light) with a longer wavelength than is visible to the human eye. IR illumination is prominent at dusk and dawn and in incandescent lamps. IR illuminators come in the form of lamps with the appropriate filters, LEDs, or lasers. CCD sensors are less sensitive to IR than visible light, but IR can significantly increase the total illumination level, leading to a much better image at low light levels.

Infrared Light

Light with a wavelength that is too low to be seen by the human eye.

Infrared Motion Sensor

A sensing unit that detects motion based on the disruption of infrared light waves.

Ingress Protection

An international rating system which classifies the ability of an item of equipment to withstand ingress from either solid particles or liquids. Otherwise known as the ‘IP’ rating.


An electronic sensor on a controller that detects a change of state in a device outside the controller. See Normally-Closed, Normally-Open

Insertion Card

A card that must be inserted into a reader for the reader to retrieve the information stored on the card.


A material which will not pass electrical current except at high voltages.

Intelligent Device

Any type of microprocessor-based input, output, or sensor device that has free-standing logic capability. These devices can be programmed with instructions that allow them to make their own decisions regarding granting access and sounding alarms. They also can communicate with a host computer to receive new instructions or to send event message logs.


Apparatus used to monitor or control parts of a fire protection system or external equipment.

Intermodal Dispersion

See Modal Dispersion


A signal placed on the communications protocol by a manual call point during polling of another device. The purpose of the interrupt is to minimise the time delay between operation of a manual call point and sounding of the alarm. Apollo patented.

Intrinsically Safe (IS)

A range of devices that have been specifically developed for use in hazardous areas where an explosive mixture of air and gas or vapour is or may be present. These areas typically include petroleum and chemical engineering plants and factories processing and storing gases, solvents and other volatile substances.

IS devices must be approved by a body such as BASEEFA/ATEX.

Ionisation Detector (Ionization – US)

A smoke detector incorporating a radioactive isotope to ionise air and cause a small current flow between an inner (reference) and outer (smoke) chamber. Smoke entering the outer chamber causes an imbalance in the current flow which in turn causes the detector to change to the alarm state.


Internet Protocol: The main protocol used on the Internet, normally in conjunction with TCP (Transfer Control Protocol); (see TCP/IP).

IP 66

IP code (Ingress Protection) that indicates the degree of protection provided by enclosures for electrical equipment. The first number indicates protection of internal equipment against the ingress of solid foreign objects. The second number indicates protection of internal equipment against harmful ingress of water. Higher digits refer to higher levels of protection. See also NEMA Rating.

IP Address

The address of a device attached to an IP network. Each device on an IP network must use a unique address. Every IP data packet contains a source address (sender) and a destination address (recipient). Each IP address consists of 32-bits that are arranged into four 8-bit octets (x.x.x.x). IP addresses range from to


Images per Second: a measurement of the rate that pictures are displayed to create a video stream. A rate of 25 IPS (PAL) or 30 IPS (NTSC) is generally considered to be full motion video.


Institute of Radio Engineers: A measurement of video amplitude that divides the area from the bottom of sync to peak white level into 140 equal units – 140 IRE equals 1V peak-to-peak. The range of active video is 100 IRE. The institute itself was founded 1912 in New York City, merged to form IEEE in 1957.


Internet Small Computer System Interface: Protocol that manages storage via a TCP/IP network. iSCSI enables access to stored data from everywhere in the network.


Integrated Services Digital Network: Comprised of digital telephony and data-transport services offered by regional telephone carriers. ISDN involves the digitization of the telephone network, which permits voice, data, text, graphics, music, video, and other source material to be transmitted over existing telephone wires.


A device which senses and isolates a short-circuit on an Apollo analogue addressable loop.



Joint Photographic Experts Group: The name of the committee that created a standard for encoding still images.


A plugable, movable device that allows connections to be made between points on a circuit board.



Kilobits per second: The actual data rate.

Key Tag

An access control identification device assigned to an individual to give that individual access rights to an access control system. Typically, the tag is attached to a key ring or similar device to provide quick, convenient access to the tag. Each tag has a unique identification code. That identification code is used by a controller to determine through which doors and at what times of day cardholders are granted access to a secure area. See Card

Keyless Access Control

An access control system that controls access using something other than a key and a lock; typically some kind of reader and an electric door lock.


An alphanumeric grid which allows a user to enter an identification code.


A lockable switch operated by a key.



Local Area Network: A communications network serving users within a limited geographical area, such as a building or a university campus. It is controlled by a network operating system and uses a transfer protocol.

Latching Relay

A relay that when set (either ON or OFF depending upon the relay configuration), locks into place until reset either manually or by a signal.


The abbreviation for Liquid Crystal Display.

Lease Line

See Dedicated Telephone Line.


The abbreviation for Light Emitting Diode.

Line Drop

The drop in voltage along a power line caused by the resistance, reactance, and/or leakage in the line’s wires.

Line Type Detector

A device for detecting the products of a fire along a defined line in the protected area. An example of a line type detector is aBeam Detector.

Lock Relay Output

A relay on the controller that changes its state upon command by the controller, locking or unlocking a secure door.


Creating and storing a permanent record of events that can be reviewed, printed, and analyzed.


A wiring configuration in which the cables carrying power and signals start and end at the control panel. Used in analogue addressable systems. Detectors and interfaces may be connected at any point of the loop.


Logical Unit Number: Logical drive in iSCSI storage systems.


The International System Unit (see SI) of measurement of the intensity of light. It is equal to the illumination of a surface one meter away from a single candle.



Media Access Control: A quasi-unique identifier attached to most network adapters (NICs). It is a number that acts like a name for a particular network adapter.

Magnetic Contact

A device that sends a signal when the magnetic field between two monitored points is broken.

Magnetic Lock

A door lock made up of an electromagnet and a strike plate. The electromagnet is mounted in the door frame; the strike plate in the door. When power is applied to the electromagnet, the strength of the electromagnet keeps the door locked.

Magnetic reed contacts

These devices use magnets fitted to doors. When the door is closed, two metal strips secured within a glass phial come together, completing a circuit. Once the door is opened, the circuit is broken, activating the alarm. There are four types:
Flush contacts are fitted inside the door frame and are invisible when the door is closed. Surface contacts are housed in PVC boxes and are generally used for external doors. Heavy duty contacts are as surface, housed in metal boxes with stronger magnets. They are generally used for ill fitting doors. Shutter contacts are fitted to the floor and are generally used for roller shutters and metal sliding gates.

Magnetic Stripe Card

An access control card with a strip of recordable magnetic material, on which data is encoded.

Magnetic Stripe Reader

A reader capable of reading and interpreting cards using magnetic stripes to encode data.

Master Code Card

An access control card that grants access and exit at every card reader on the system.


The section of a host computer or a controller in which data and instructions are stored.


Management Information Base: A collection of information for remote servicing using the SNMP protocol.


Motion JPEG is a digital video encoding standard where each video frame is separately compressed into a JPEG image.

Modal Dispersion

A broadening of a waveform over long distances. Modal Dispersion (or Intermodal Dispersion) occurs in multimode fibers, because light is bounced down different reflective paths (e.g. modes) in the fiber. As the distance increases, the path (mode) begins to spread and the arrival time for the different light rays begins to vary. A large variance (dispersion) increases the chance that the optical receiver may interpret the incoming signals incorrectly. Modal dispersion is a major problem with multimode fibers.


A communication device that converts computer serial data to an analog format that can be transmitted and received via telephone.


A further development of MPEG-2 designed for transmitting audiovisual data at very low transfer rates (for example over the Internet). A digital video encoding and compression standard that uses interframe encoding to significantly reduce the size of the video stream being transmitted. With interframe coding, a video sequence is made up of keyframes that contain the entire image. In between the keyframes are delta frames, which are encoded with only the incremental differences. This often provides substantial compression because in many motion sequences, only a small percentage of the pixels are actually different from one frame to another.


A convention or standard that controls or enables the connection, communication, and data transfer between two devices. In PTZ cameras, such as the AutoDome and Pan/Tilt units, protocol refers to the standard used to control the pan, tilt, and zoom (PTZ) operation of the camera. Since each camera manufacturer’s PTZ protocols are unique, multi-protocol support is needed to support third party systems. AutoDome cameras support the Pelco D and P protocols as well as Bosch’s own Biphase protocol (see Biphase). The Pan/Tilt units support the Pelco “D” protocol as well as Bosch’s own Biphase and Bilinx protocols (see Bilinx).

Multimode Fiber

An optical fiber with a larger core (typically 50 or 62.5 microns) than singlemode fiber (see Singlemode Fiber). The core is made of plastic or glass fibers. It is the most commonly used fiber for cabling short distances as used in LANs. The name multimode comes from the fact that light rays travel down multiple reflective paths (modes) within the fiber. This allows light to enter the core at different angles, making it easier to connect to broader light sources such as LEDs (light emitting diodes). Fiber optic interfaces and multimode fiber-based transmission systems are less expensive than those based on singlemode fiber. However, the use of multiple reflective paths (modes) increases modal dispersion (see Modal Dispersion) and shortens the distances that this type of fiber optic transmission system can span.


NEMA Rating

Electrical Standards and Publications published by NEMA (National Electrical Manufacturers Association). Specification standards in reference to the operating environment for a variety of electrical devices.

Net mask

A mask that explains which part of an IP address is the network address and which part is the host address. It is usually written in dotted decimal notation, for example (see also Subnet Mask).


1) A series of controllers, all connected via a communications cable. 2) A group of computers, all connected via a communications cable.


A method of boosting the sensitivity of high-resolution Bosch color cameras by 9 db (a factor of 3) by combining the signal of the color image in a single monochrome picture.

Non-Addressable System

A system in which signals from detection and alarm devices are indicated by zone at the control and indicating equipment. Also known as a ‘conventional system’.


The state of an input device that continually keeps a circuit closed or complete until forced by an action or event to open that circuit. See Input.


The state of an input device that continually keeps a circuit open or incomplete until forced by an action or event to close that circuit. See Input.


National Pipe Thread: A U.S. standard for tapered threads. NPT sizes measure the nominal inside diameter of the pipe. NPT threads form a seal as the threads compress against each other.


Network Time Protocol: A standard for synchronizing computer system clocks via packet- based communication networks. NTP uses the connectionless network protocol UDP (see UDP). This was developed specifically for enabling time to be reliably transmitted over networks with variable packet runtime (Ping).



A term used to describe the amount of light blocked out by smoke particles between the transmitter and receiver of an optical smoke sensing device.

Online Help

A reference program within most software programs that provides basic descriptions and instructions on how to use that software program.

Open Protocol

This term describes a protocol that has been designed for compatibility with apparatus from other manufacturers of electronic equipment. See also ‘closed protocol’.

Optical Detector (Photoelectric – US)

A smoke detector using light scatter or obscuration techniques to detect smoke.

OR Gate

A logic circuit that requires that any input must be in a high state (logic 1) to generate a high state output (logic 1).


On-screen Display: Menus are shown on the display monitor.

Output Relay

A device that changes its state upon receiving a signal from a controller. Typically the state change prompts an action outside of the controller such as activating or inactivating a device.



Camera movement in the horizontal direction.

Panic Bar

A quick release door lock allowing the door to be quickly opened in the case of an emergency situation. Also Known As – Crash Bar.


Values used for configuration.

Passive Infrared Movement Detectors

For domestic and office applications, SECOM normally employs wide-angle ‘quad zone logic detectors’. These are intelligent devices that provide very stable detection, recognising the difference, for example, between humans and rodents. Electronic chips process the information even further to filter out false alarms.

Personal attack buttons

These units employ two buttons, which have to be pressed at the same time to activate an alarm. They work around the clock and can sound an audible alarm, or can silently alert SECOM’s receiving centre.

Personal Identification Number (PIN)

A unique numerical code used to identify an individual.

Photo Badging

See Badging Software.

Photoelectric Detector

See ‘Optical Detector’.


1) More than one individual entering a secure area using one access card. 2) Following an authorized person into a secure area. Also Known As – Tailgating. See Anti Passback.


See Personal Identification Number.


The smallest addressable unit on a display screen or bitmapped image.

Point-Type Detector

A device for detecting the products of a fire at a defined point within the protected area. Most smoke detectors are point type detectors.

Police guidelines (DD:243)

DD:243 are guidelines introduced to help alleviate false alarms; reducing police time wasted in attending sub-standard and problematic systems. The guidelines outline that alarmed areas need to be covered by two or more detector devices using different technologies (see Detection Devices). Only if the second detector is activated within 30 minutes after the first device will the police respond. A single alarm activation alerts the ARC who notify the keyholder.


1) On computer and telecommunication devices, a port (noun) is generally a specific place for being physically connected to some other device, usually with a socket and plug of some kind.Typically, a personal computer is provided with one or more serial ports and usually one parallel port. 2) In programming, a port (noun) is a logical connection place and specifically, using the Internet protocol TCP/IP, the way a client program specifies a particular server program on a computer in a network. Higher-level applications that use TCP/IP, such as the Web protocol Hypertext Transfer Protocol, have ports with preassigned numbers. These are known as well-known ports that have been assigned by the Internet Assigned Numbers Authority (IANA). Other application processes are given port numbers dynamically for each connection. When a service (server program) initially is started, it is said to bind to its designated port number. As any client program wants to use that server, it also must request to bind to the designated port number. Port numbers are from 0 to 65535. Ports 0 to 1024 are reserved for use by certain privileged services. For the HTTP service, port 80 is defined as a default and it does not have to be specified in the Uniform Resource Locator (URL).


A Pre-selected and stored combination of pan, tilt, and zoom positions that allow a set view to be recalled. Also known as Preset Shot.

Preset Tour

A sequence of preset shots combined to provide a pre-programmed tour of the area covered by a programmable camera.

Pressurized Dry Nitrogen Housing

A housing for outdoor applications that protects against smog, humidity, dirt, and dust.

Primary Code

The main identification information provided by an individual to gain access to a secure area. See Auxiliary Code.

Privacy Masking

The ability to mask out a specific area to prevent it from being viewed.

Programmable Card

A card in which data may be encoded.

Programmable Card Reader

A card reader in which instructions for granting or denying access may be programmed.


The term ‘protocol’ is the method that electronic devices use to communicate with each other.


A method of reading a card or key tag without requiring any physical contact between the card/tag and the reading device. Click Here for a description of the operating principle behind proximity.

Proximity Card

A card using proximity technology to store and transmit encoded data.

Proximity Reader

A reader capable of reading and interpreting cards using radio frequency identification to encode data.

Push-Button Lock

A lock that opens when a set of push-buttons are pressed in sequence or in unison.



Quarter CIF: Video format with 176 × 144/120 pixels (see CIF).


The state in which a device is operating normally, in non-fire conditions.


Radio Frequency Identification

A method of reading a card using radio frequency energy to transmit information from the card to a reader. See Proximity.


Remote Authentication Dial-In User Service: A client/server protocol for the authentication, authorization, and accounting of users with dial-up connections on a computer network. RADIUS is the de-facto standard for central authentication of dial-up connections via a Modem, an ISDN, a VPN, a Wireless LAN (see IEEE 802.1x), and a DSL connection.


Redundant Array of Independent Disks: Used for organizing two or more hard disks as if they were one drive. On such a drive data is shared or replicated. This is used to achieve greater capacity, reliability, and speed.

Random Access Memory (RAM)

Randomly addressable, readable and writable memory (either volatile or nonvolatile) whose contents may be read or be altered at will.

Rate-of-Rise Heat Detector

A device that incorporates 2 thermistors, 1 internal and 1 external, to sense temperature. If the temperature increases quickly, the thermistors register different temperatures and the detector changes to the alarm state.

RDM (Radio Detector Monitoring)

A range of Apollo devices utilising radio linked technology compatible with XP95. Now obsolete.

Read Only Memory (ROM)

Nonvolatile memory whose contents are programmed into the ROM when the ROM is made, and therefore cannot be altered. ROM is typically used to store programs and fixed data sets.


A device that “receives” an identification code from a card, key tag, magnetic stripe card, bar code card, or related item.

Real Time Command

A command that is executed immediately, with no time delay.

Recommended Working Life

The recommended working life of Apollo detectors is 10 years when used in dry, non-corrosive atmospheres and provided that they are regularly inspected, tested, cleaned and recalibrated correctly.

Region of Interest

A specific area within a field of view, used by the motion detection algorithm to identify motion.


A device that is capable of opening a normally-closed circuit or closing a normally-open circuit. When the relay is not energized, the normally-closed circuit is complete and the normally-open circuit is open. When the relay is energized, it switches roles, opening the normally-closed circuit and closing the normally-open circuit. This dual nature of a relay allows for two types of applications: a device may be attached to the normally-closed circuit so that the device is always on until the relay energizes to turn it off, or a device may be attached to the normally-open circuit so that the device is always off until the relay energizes to turn it on.


This is a patented feature of the Apollo AlarmSense range of detectors and means that the AlarmSense control panel is alerted if a detector is removed from its base without authorisation.

Repeater Panel

An indicating panel which mimics the displays and other features of a main control panel. The panel can either be active ie able to control all or part of the system, or passive ie to simply provide information.

Request to Exit (RTE)

A signal that informs the controller that someone has requested to exit from a secure area.


The measure of the fine detail that can be seen in an image. For analog systems this is typically measured in Television Lines or TVL. The higher the TVL rating, the higher the resolution.

Retro Mode

If it is difficult to fit the XP95 Beam Detector’s transmitter and receiver on opposite walls, they can be placed adjacent to each other. One or more reflectors need to be fitted to the opposite wall to reflect the beam emitted from the transmitter to the receiver.

RFC 868

A Request For Comment protocol for synchronizing computer clocks over the Internet.


See Radio Frequency Identification.


A serial communication protocol used for connecting data terminal devices. RS-232 is the most commonly used communication protocol.


A serial communication protocol used for multi-drop communication applications. It is used for higher speed and longer distance communications.


Recommended standards for serial data transmission. A communication interface for third party control, firmware upgrades, and service purposes for camera and DVR products.


Realtime Transport Protocol: A transfer protocol for real-time video and audio.


An alarm management subsystem that uses rules to perform specific actions when an event occurs.


Sector blanking

The ability to blank out video in any number of the pan sectors.

Secure Area

A designated area in which access into and out of is controlled and can be monitored.

Secure Door

A door in which access through is controlled and can be monitored.


SensAlert is a feature of Orbis which uses a flashing yellow LED to indicate that the sensor is not operating correctly.


A measure of the amount of light required to provide a standard video signal. Sensitivity values are stated in lux (see Lux) or foot-candles.


Ups (increases) camera sensitivity by increasing the integration time on the CCD. This is accomplished by integrating the signal from a number of consecutive video frames to reduce signal noise.

Série 50

A range of conventional devices, designed to comply with French standards.

Series 20

A range of conventional devices manufactured by Apollo from 1986 – 1996.

Series 30

A range of conventional devices manufactured by Apollo from 1984 – 1996.

Series 60

A range of conventional devices manufactured by Apollo.

Series 65

A range of conventional devices using a wide operating voltage, manufactured by Apollo.

Series 90

Apollo’s first range of analogue addressable devices manufactured from 1987 – 1996.


Small Form-factor Pluggable: A small, standardized module for network connections; designed as a plug connector for high-speed network connections.


Providing electrical isolation for a circuit, component, or wire by enclosing or isolating the circuit, component, or wire with a metal enclosure, plate, or foil that blocks any interfering electrical field.

Short Circuit

An unintentional connection that provides a low resistance path between two points in a circuit or between a point in a circuit and ground. A Short Circuit can drastically affect the operation of a circuit. If excessive current flow results from the Short Circuit, a device may be damaged or ruined.


1) Deliberately shorting a portion of an electric circuit. 2) A device for shorting an electric circuit. See Short Circuit.


International System of Units (abbreviated SI from the French Le Système international d’unités): The world’s most widely used system of units, both in everyday commerce and in science.

Signature Verification

A biometric identification method using a person’s signature characteristics (writing speed, pen pressure, shape of loops, etc.) to identify that person.

Single Quadrant Terminals

These are four terminals grouped together for ease of installation of the Orbis TimeSaver Base.

Singlemode Fiber

An optical fiber with a silica (or glass) core with a diameter of less than 10 microns. Used for high-speed transmission over long distances, it provides greater bandwidth than multimode (see Multimode Fiber), but its smaller core makes it more difficult to couple the light source.Singlemode fiber optic transmission systems use more expensive laser-based light sources.

Smart Card

An identification card or access control card with a built-in integrated circuit chip. This gives the card microprocessor memory and intelligence to use for storing data. Also Known As – Chip-In-Card.

Smoke Detector

A device which utilises optical, optical/thermal or ionisation techniques to detect smoke particles.


Storage Networking Industry Association: Association of companies for defining the iSCSI standard.


Simple Network Management Protocol: IP based protocol for network management, as well as managing and monitoring network components. SNMP allows getting information from networking devices (GET), to set parameters on network devices (SET), and to be notified about certain events (EVENT).


Simple Network Time Protocol: A simplified version of NTP (see NTP).

Solo Test Equipment

Apparatus used for the in-situ testing and maintenance of fire detectors.


A device used to produce an audible indication of alarm.


A voltage peak of high amplitude and short duration. See Transients.

Spot Focus

Activates Auto Focus for three seconds after camera movement.


StartUp is a feature of Orbis which uses a flashing red LED to confirm that the devices are correctly installed.


A device used to produce a visible indication of alarm.

Subnet mask

Subnetting is a method that allows one large network to be broken down into several smaller ones. IP addresses are grouped by something called a subnet mask. Every IP address has a corresponding subnet mask. The subnet mask specifies the range of the IP addresses in a group. The subnet mask looks a lot like an IP address. It is made up of four eight-bit numbers separated by periods. These numbers once again range from 0 to 255. A typical subnet mask is


The addition of a device to an electrical circuit that minimizes or prevents transients from affecting the proper operation of that circuit.


A device used to either connect or interrupt an electronic circuit.


This is a patented feature of the Apollo AlarmSense range of detectors. This technology means that pulsing sounders are synchronised when they are in alarm.



1) More than one individual entering an secure area controlled by an access control system using one access card. 2) Following an authorized person into a secure area. Also Known As – Piggybacking. See Anti Passback.


Transmission Control Protocol/Internet Protocol: a communications protocol suite that provides two data transport methods. TCP is a connection-based protocol that ensures that data arrives intact and complete. UDP is a connectionless, best effort protocol that simply sends out packets. UDP is typically used for streaming media, while TCP is used when error-free delivery is required.

Telephone Entry

An access control system that allows users outside a secure area to use a telephone to contact someone inside the secure area and request access.


Log in protocol with which users can access a remote computer (Host) on the Internet or local area network (LAN) connections.


Camera movement in the vertical direction.

TimeSaver Base

The Orbis TimeSaver Base is a completely new design that provides installers with an open working area and single quadrant terminals.


A specified period of time in which access is allowed. A variety of timezones may be defined to accommodate the access needs of a variety of people.


Transport Layer Security: TLS 1.0, 1.1, and the standard advanced developments of SSL 3.0 (Secure Sockets Layer, the predecessor to TLS).


See Keypad.

Transient Rejection

Transient rejection uses algorithms to filter out temporary abnormal readings, helping to reduce false alarms.


Electrical surges or spikes conducted through power or data lines. Transients are typically generated as electrical devices are turned on or off. See: Suppression.


An electrical suppression device. See: Suppression.


A Bosch encoding technology that generates two separate MPEG-4 video streams and one MJPEG stream simultaneously. This advanced streaming capability enables the user to tune live viewing and recording requirements independently to meet specific site and enterprise requirements.


Time-To-Live: Life cycle of a data packet in station transfers.


An entryway that uses a mechanical device to restrict entry to one person at a time.


A system that allows detection and alarm devices to be connected to the same pair of wires.



User Datagram Protocol: One of the core protocols of the Internet Protocol suite. Using UDP, programs on networked computers can send short messages, sometimes known as datagrams, (using Datagram Sockets) to one another. UDP is sometimes called the Universal
Datagram Protocol.


The UL label on a product signifies that the product has met the Underwriters Laboratories requirements and that the product manufacturer is authorized to use the UL symbol on their products.


Sending information from a peripheral device to the host computer in an access control system.


Uniform Resource Locator: Previously Universal Resource Locator. The unique address for a file that is accessible on the Internet.


Unshielded Twisted Pair: A variant of twisted pair cabling, UTP cable is not surrounded by any shielding. The wires in a twisted pair cable are twisted around each other to minimize interference from the other twisted pairs in the cable. UTP is the primary wire type for telephone usage and the most commonly used type of networking cable.



The process of identifying an individual and allowing them access based on some type of provided information which has to be entered into an access control system. Verification may be done using by methods such as access cards, biometric information, PIN code, voice recognition, etc.

Vibration detectors

These are normally fitted to door or window frames and are designed to detect high and low frequency vibration within a range. They can be adjusted to suit local conditions.

Virtual Masking

A unique Bosch technology that creates invisible motion masking areas. These invisible masks are similar to privacy zones but only the camera’s algorithms can see them. This allows the camera to ignore areas of unwanted motion.


Video Motion Detection: An algorithm for motion detection in which the CCTV surveillance system camera compares the current image with a reference image and counts the number of pixels (see Pixel) that have changed between the two images. An alarm is generated when the number of pixel changes exceeds a user-configured threshold.

Voice Recognition System

An access control system that verifies a person’s identity by comparing previously stored voice recordings key words or phrases with the same key words or phrases spoken at the time access is requested.



Wide Area Network: A long distance link used to extend or connect remotely-located local area networks.

Wide Angle Optics

Wide Angle Optics are a feature of Orbis and give a good response to fires generating white or black smoke.

Wiegand Card

An access control card based on the Wiegand effect. Small bits of specially processed wire are embedded in the card in a pattern that uniquely identifies the card. This identification information can then be decoded by a Wiegand reader.

Wiegand Compatible Devices

A propriatary coding format for information used by many of the suppliers of cards, key tags, proximity readers, magnetic stripe readers, bar code readers, and related items.

Wiegand Effect

Electrical pulses generated when individual sections of specially processed magnetic wire is passed by a pickup coil. Each section of this magnetic wire has its own magnetic field. Depending upon the strength of the individual magnetic fields, the pickup coil either senses a strong field or overpowers a weak field, which generates an electrical pulse.

Wiegand Reader

A reader capable of reading the information encoded on a Wiegand card.



A highly accurate, 15-bit digital signal processing technology from Bosch that extends the dynamic range of DinionXF cameras. XF-Dynamic optimizes the detail in both the high and low light areas of the scene simultaneously, maximizing the information visible in the picture.


A range of analogue addressable devices manufactured by Apollo. Detectors are addressed using a unique, patented mechanism – the XPERT card.

XP95 Test Set

A diagnostic tool used to identify faults on any XP95, Series 90 and Discovery loops. The test set can also be used to test individual devices.


A unique, patented addressing method to accurately identify a detector’s location. The coded XPERT card is inserted into the base which can then be read by any XP95 (or Discovery or XPlorer) detector once it is plugged in. Using this method, all the electronic components are in the detector but the location information is held in the base. The XPERT card simplifies and speeds up installation and commissioning.


A range of analogue addressable devices with limited functionality, manufactured by Apollo.



A zone is an area within a fire detection system and is defined by local standards such as BS 5839–1.


Changing the effective focal length to allow different fields of view to fill the picture area. Zoom can be optical, where the lens is adjusted, or digital, where a portion of the view selected is magnified electronically.