Glossary

Symbols Back to Index

2nd Line - a programming option that allows you to use a second phone line to send reports to the central station receiver should the first phone line fail.

24-hour zone - a zone that is not turned on or off by system arming or disarming.

4-2 Communication - a hexadecimal communication format that allows the DMP panel to send alarm and system reports to non-DMP receivers. The 4-2 format consists of a 4-digit account number, a 2-digit event code, and a 1-digit checksum.

4-Wire Bus Trouble - a keypad message indicating trouble on the keypad bus. This message is generated when one of the following conditions occur:

• Two Supervised devices on the keypad bus are set to the same address.
• No supervised devices on the keypad bus.
• Low data voltage on the yellow wire of the keypad bus.

10BaseT - the industry standard use of 10-Mbps Ethernet over unshielded twisted pair cabling.

A Back to Index

“A” Zone (Style D) - a circuit extending from and returning to a fire alarm control device or transmitter to which alarm actuating device normally open contacts are connected for alarm signal initiation. See “B” zone.

Abort - an authorized system user manually cancels an alarm after an armed zone trips. Used mainly when the zone trip was accidental, such as the opening of an armed door, and a police or fire response is not needed.

Abort Report - a report sent by the panel following an alarm report to indicate the alarm has been cancelled by an authorized user and no dispatch is required.

AC Line - power line delivering alternating current.

AC Noise - electric noise of a rapidly alternating or pulsating nature. Can interfere with DMP bus in some cases.

AC Power Supply - a power unit, like a generator, transformer, or inverter, which supplies AC power.

Access - the ability or opportunity to enter an area or to obtain knowledge of certain information.

Access Code - 1) a combination of PIN numbers and door locations related to a defined schedule. These combinations are programmed into an access system to grant or deny access to system users. 2) programmer lockout code is a programming option that allows you to enter a special code into the panel that is then required to gain access to the panel internal programmer through the keypad. You can change this code at any time to any combination of numbers from one to five digits long. Once you change the code, it is important that you write it down somewhere and store it in a safe place. Lost lockout codes require the panel to be sent back to DMP for repair.

Access Control - the control of persons through controlled area or premise entrances and exits.

Access Control Card - a card containing coded information. It is placed in or near a card reader. The card is read and access is granted if the information from the card is valid for that specific time, day, and location.

Access Keypads - a programming option that allows door access reports to be sent to a receiver. A report is sent with each door access made from selected keypads. Keypads at addresses not selected still operate the door strike relay but do not send door access reports.

Access Parameters - specifications programmed or entered into an access control system to define authorization levels, entry times, identification codes, and other system information.

Access Point - a door, gate, or other barrier through which people or vehicles can gain access to a defined area.

Access Privileges - controls placed on network services that limit and control user access through doors.

Account - A residence or business whose alarm system is maintained or monitored by an alarm company or central station.

Account Number - the number that identifies all reporting systems to the central station. The account number is included along with any reports the panel sends to the receiver.

Acknowledge - the confirmation that a message or signal has been received, such as pressing a button or selecting a software command.

Action - a zone programming option that selects the action of any outputs activated by changes in the zone condition. The four action options are - steady pulse (1 second on, 1 second off) momentary (1 second on for one time only) follow (on when the zone is off normal, off when the zone restores).

Active Multiplex System - a system in which multiple signaling devices, such as transponders, are used to transmit status signals of each initiating time interval so that a failure to receive such signal may be interpreted as a trouble signal.

Active Star - a network with a multi-port repeater at the center. Each device connects to the repeater. Active stars do not perform network addressing. Network packets seen on one branch of the star are seen on all branches.

Activity Report – a record of openings, closing, alarms, and other signals received from a protected premise and maintained by the central station alarm company.

Actuator - a manual or automatic switch that initiates an alarm transmission to the central station when activated.

Address - 1) a switch setting on a keypad, zone expander, or other device that reflects its assigned position on a data bus. Zone expanders, for example, are addressed so that the panel is able to associate its on-board zones with their programmed location and characteristics held in memory. 2) a sequence of bits used to identify devices on a network. Each network device must have a unique address. Addresses fall in two categories - physical hardware addresses and logical protocol addresses.

Addressable Device - an alarm system component with discrete identification that can have its status individually identified or that is used to individually control other functions.

Addressable System Smoke Detector - system smoke detectors that, in addition to providing alarm and trouble indications to a control unit, are capable of communicating a unique identification location address.

Adverse Condition - any condition occurring in a communications or transmission channel that interferes with the proper transmission or interpretation, or both, of status change signals at the supervising station.

Ah - Ampere-hour.

Air sampling-type detector - a detector that consists of a piping or tubing distribution network from the detector to the area(s) to be protected. An aspiration fan in the detector housing draws air from the protected area back to the detector through air sampling ports, piping, or tubing. At the detector, the air is analyzed for fire products.

Alarm - a condition in which one or more armed zones in the system have faulted. Almost all alarms sound some form of audible device locally, except in the cases of silent panic or ambush alarms.

Alarm Bell - a bell or siren installed on the protected premises that gives indication of an alarm condition to persons inside or nearby.

Alarm Circuit - an alarm system electrical circuit that produces or transmits an alarm signal.

Alarm Control - a device that permits an alarm system to be turned on and off and provides electrical power to operate the system. Every alarm system must have an alarm control.

Alarm Indicating Device - an audible or visual signal used to signify an alarm signal, such as a bell or strobe.

Alarm Initiating Device - a device that initiates an alarm when actuated. Such devices, depending on their type, can be operated manually or actuated automatically in response to smoke, flame, heat, or water flow.

Alarm Module - an add-on device to monitor a series of sensors and initiate warning devices if required.

Alarm Panel - the main controlling CPU in the alarm system to which all zones, phone lines, and devices are connected.

Alarm Receiver - a device used to receive alarm events from alarm panels. Receivers are usually located and maintained at a central station company.

Alarm Shunt Period - the length of time a door can remain open before causing an alarm.

Alarm Signal - 1) an audible or visual signal produced by the alarm panel indicating the existence of an alarm condition. The alarm signal may be a bell, siren, or visual device (local alarm), or it may be a message transmitted to a central station alarm company on leased telephone lines, the Internet, or the switched network. Every alarm system must have an alarm signal. 2) used to refer to the actual signal sent to a alarm receiver.

Alarm Silence - a keypad menu function that allows authorized users to silence alarm bells or sirens during an alarm condition on the system. Users can also enter their user code and press the COMMAND key directly from the status list. This is an exclusive function of DMP panels that allows silencing alarm bells without disarming the system.

Alarm System - a combination of compatible initiating devices, control panels, and notification appliances designed and installed to produce an alarm signal in the event of emergencies.

Alarm Verification – a feature of automatic fire detection and alarm systems to reduce unwanted alarms wherein automatic smoke detectors must report alarm conditions for a minimum period of time, or confirm alarm conditions within a given period of time after being reset, to be accepted as a valid alarm initiation signal.

Alert Tone - an attention-getting signal to alert occupants of a voice message pending transmission.

All/Perimeter - a panel mode of operation that provides for the system to be configured into just two areas - a perimeter and an interior. Exterior doors and windows are assigned to the perimeter, while inside devices such as PIRs and doors are assigned to the interior area.

Alphanumeric – term used to describe a combination of letters and numbers.

Alternating Current (AC) - an electric current that reverses its direction regularly and continually. The voltage alternates its polarity and current flow direction from negative to positive. AC current increases to a peak, decreases through zero, and peaks in the opposite direction. AC current flows back and forth in the conductor and is expressed in cycles per second, or Hertz (Hz).

Ambient Temperature - the temperature of the air immediately surrounding a device or object.

Ambush - a silent, invisible alarm signal sent to the central station that indicates a user is being forced to disarm the system. DMP panels use a unique ambush code number to prevent false alarms.

Ambush Code - a special code entered to indicate a duress condition that directly threatens the user. The ambush signal is sent when ambush is programmed as YES in the panel and a code for user number one is entered at the keypad. This code does not activate signaling devices at the premises.

Ambush Output - a panel output that is programmed to activate any time an ambush code is entered at a keypad. The output is turned off through the user menu sensor reset option. This output is used to lock down areas or activate strobes, etc.

American National Standards Institute (ANSI) - a federation of trade, technical, professional organizations, government agencies, and consumer groups that coordinates standards development, publishes standards, and operates a voluntary certification program.

American Standard Code for Information Interchange (ASCII) - a commonly used coding scheme that uses eight bits of data to encode alphanumeric and special control characters. Common to most computer platforms.

American Wire Gauge (AWG) - the U.S. standard for specifying the diameter of a wire conductor. The larger the number, the smaller the wire.

Ampere (Amp) - the unit of measurement for the rate of electrical current flow, characterized by the symbols I (in Ohm’s law formulas) or A. One Ampere is the current flowing through one ohm of resistance at one volt potential.

Ampere-hour (Ah) - a measurement of a battery capacity. One Ampere of current flowing for one hour equals one Ampere-hour.

Amplitude - the magnitude of an electrical signal. Measured by subtracting an electrical signal minimum voltage from its maximum voltage.

Analog - a method of data transmission where the data is continually modulated to represent transmitted information.

Analog System Smoke or Heat Detectors – a system detector that returns many levels of information to the control panel. Alarm decisions are made by the panel, not the detector.

Annunciator - a keypad or other lighted or audible display at the protected premise that indicates system, zones, and armed status conditions.

Anti-passback – a programming option that requires a user to properly exit (egress) an area they have previously accessed. If they fail to exit through the proper card reader location they are not granted access on their next attempt. Also, see Egress.

Any Bypass - a panel programming feature that allows low level users to bypass zones during the arming sequence without having to enter a higher level user code.

Area - part of a protected premise, such as the front office, that is programmed to operate separately from the other parts of the premises. Areas can have their own keypads, zones, account numbers, and arming and disarming schedules.

Area Arming - a panel operation mode that provides for one or more individual areas to be individually armed and disarmed.

Area Schedules - a programming option that allows you to assign an individual schedule to each area within the system. This allows each area to open and close on independent schedules. When area schedules are turned off, all areas follow the same schedule.

Arm - to turn on the protection in a protected premises.

Armed - a condition in which a zone or system can be placed. When a zone is armed, a change in its normal state causes the panel to activate an alarm. Fire, panic, and other 24-hour zones are considered always armed.

Armed Output - a programming option that allows an output to activate when an area arms.

Armed Rings - the number of rings the panel counts before answering the phone line when all system areas are armed.

Arming Zone - a DMP zone type that allows you to use keyswitches to arm and disarm areas within a system. This is done by entering the area number(s) to be controlled into the arming zone programming area section.

Arrow Key - a Security Command® keypad function key that allows you to back up one step while in the programmer or user menu. The Arrow key also lets you delete previous characters entered into the keypad while programming.

Asynchronous Communication - a data transmission mode that transmits individual characters or bytes, one at a time, along with individual start and stop bits.

Audible Alarm Device - a noisemaking device such as a siren, bell, or horn, used to indicate a local alarm.

Authority Having Jurisdiction (AHJ) - the organization, office, or individual responsible for approving equipment, an installation, or a procedure. The AHJ may be a federal, state, local, or other regional department or individual, such as a fire chief, fire marshal, chief of a fire prevention bureau, labor department, health department, building official, electrical inspector, or others having statutory authority. For insurance purposes, the AHJ may be an insurance inspection department, rating bureau, or other insurance company representative.

Authority Level - a level of access to the system and its functions that is assigned to each user code or user profile. Each area must have at least one user with a Master authority in order to be able to add, change, or delete other users.

Auto Arm - to automatically turn on the burglary protection in one or more areas through the use of schedules. These schedules allow you to set the time of day for the arming to occur. If using the automatic arming feature along with the closing check (see Closing Check), the arming does not take place until the expiration of a ten-minute closing check delay. If the area is disarmed outside of any schedule, the closing check sequence occurs one hour after the area is disarmed. At arming, faulted zones are handled according to the bypass option selected. If a closing report is sent to the central station, the user number is indicated as SCH (for schedule) on the receiver.

Auto Disarm - to automatically turn off the burglary protection in one or more areas through the use of schedules. These schedules allow you to set the time of day for the disarming to occur. If an opening report is sent to the central station at disarming, the user number is indicated as SCH (for schedule) on the receiver.

Automatic Fire Alarm System - a system of controls, initiating devices, and alarm signals in which all or some of the initiating circuits are activated by automatic devices such as smoke detectors. Refers to fire alarm systems that electronically detect smoke or abrupt temperature changes associated with a developing fire. Early detection and reporting to a central station allow fire authorities to respond quickly and minimize damage.

Automatic Recall Test – a signal generated by the panel that is sent to the central station. This signal indicates that the panel communicator is working properly and is able to send signals to the central station receiver.

Automation - central station software that receives signals from an alarm receiver and displays alarms on a display screen to allow the proper authorities to be dispatched.

Auxiliary Fire Alarm System - a connection to the municipal fire alarm system to transmit a fire alarm to the municipal communications center. Fire alarms from an auxiliary alarm system are received at the municipal communications center on the same equipment and by the same alerting methods as alarms transmitted by municipal fire alarm boxes located on streets.

Average Ambient Sound Level - sound pressure level measured over a 24-hour period.

Away - a panel arming mode in which all areas of the system are armed. This option is for when the user leaves the premises and no person is left inside.

B Back to Index

“B” Zone (Style A) – a circuit extending from a fire alarm control device or transmitter to which initiating or notification devices are connected. The zone is terminated with an End-of-Line supervision resistor.

Backbone Network - a network topology where devices connect to a single cable. Thickwire Ethernet networks are commonly used as backbone networks.

Back-focus - A procedure of adjusting the physical position of the CCD-chip/lens to achieve the correct focus for all focal length settings (especially critical with zoom lenses).

Back porch - 1. The portion of a video signal that occurs during blanking from the end of horizontal sync to the beginning of active video. 2. The blanking signal portion that lies between the trailing edge of a horizontal sync pulse and the trailing edge of the corresponding blanking pulse. Color burst is located on the back porch.

Backup - as used in programming for receiver one and receiver two reporting, choosing YES for this option means that the receiver is contacted by the panel in the event the primary receiver cannot be reached.

Backup Battery - a battery used as a secondary power source in the event of normal AC power failure, normally housed in the alarm panel enclosure.

Balun - This is a device used to match or transform an unbalanced coaxial cable to a balanced twisted pair system.

Bandwidth - The complete range of frequencies over which a circuit or electronic system can function with minimal signal loss, usually measured to the point of less than 3 dB. In PAL systems the bandwidth limits the maximum visible frequency to 5.5 MHz, in NTSC to 4.2 MHz. The ITU 601 luminance channel sampling frequency of 13.5 MHz was chosen to permit faithful digital representation of the PAL and NTSC luminance bandwidths without aliasing.

Bank, Safe, & Vault - an area operating characteristic that prevents disarming, schedule changes, and time/date changes during armed periods. This feature is typically used on bank vaults, but can also be used for restricted access storage, gun rooms, or other areas where the user wants an extra level of protection.

Bandwidth – the amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second (bps) or bytes per second. For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).

Barrier – a door, gate, turnstile, or similar device that a system controls access to using readers and (if equipped to do so) monitors entry or exit activity through a reader-related monitor point.

Baseband - a band of frequencies and related equipment used to carry signals in an unmodulated form.

Battery – a DC voltage source used to compensate for loss of AC power. Certain UL applications have specific standby battery requirements.

Battery Standby - a means of automatically switching over to stored battery power during local primary power failure.

Baud - Date rate, named after Maurice Emile Baud, which generally is equal to 1 bit/s. Baud is equivalent to bits per second in cases where each signal event represents exactly 1 bit. Typically, the baud settings of two devices must match if the devices are to communicate with one another.

Baud rate - The speed at which information can be transferred through a COM (serial) port. Standard baud rates range from 300, 1200, 2400, 4800, 5600, 9600, or 19200 baud.

Bell - alarm bell - a bell installed on the protected premises that gives indication of an alarm condition to persons inside or nearby.

Bell Action - an output option that defines the alarm bell output action.

• none - no bell action for an alarm condition on the zone.
• pulse - a repeating 1 second on, 1 second off output for the duration of the programmed bell cutoff time.
• steady - a steady, uninterrupted bell output for the duration of the programmed bell cutoff time.
• temporal code (Code 3) - a repeating 0.5 second on, 0.5 second off (three times) alarm followed by 2.5 seconds off. The temporal code lasts for the duration of the programmed bell cutoff time.

Bell Cutoff - the length of time the alarm bell or siren is programmed to ring after an alarm. DMP panels allow a programmable length of time in one-minute increments. Entering a zero allows the bell output to run continuously. Consult your local Authority Having Jurisdiction (AHJ) for restrictions.

BER - Bit error rate. The ratio of received bits that are in error relative to the total number of bits received, used as a measure of noise induced distortion in a digital bit stream. BER is expressed as a power of 10. For example, a 1 bit error in 1 million bits is a BER of 10-6

Betamax - Sony's domestic video recording format, a competitor of VHS.

Bias - Current or voltage applied to a circuit to set a reference operating level for proper circuit performance, such as the high-frequency bias current applied to an audio recording head to improve linear performance and reduce distortion.

Bi-metallic Heat Detector - a device that uses a sensing element composed of two metals having different thermal expansion coefficients so that they deflect in one direction when heated and in the opposite direction when cooled.

Binary - A base 2 numbering system using the 2 digits 0 and 1 (as opposed to ten digits [0-9] in the decimal system). In computer systems, the binary digits are represented by 2 different voltages or currents, one corresponding to zero and another corresponding to one. All computer programs are executed in binary form.

Binary Coded Decimal (BCD) - see Rotary Switches.

Bipolar - A signal containing both positive-going and negative-going amplitude. May also contain a zero amplitude state.

B-ISDN - Broadband Integrated Services Digital Network. An improved ISDN, composed of an intelligent combination of more ISDN channels into one that can transmit more data per second.

Bit - A contraction of binary digit. Elementary digital information that can only be 0 or 1. The smallest part of information in a binary notation system. A bit is a single 1 or 0. A group of bits, such as 8 bits or 16 bits, compose a byte. The number of bits in a byte depends on the processing system being used. Typical byte sizes are 8, 16 and 32.

Bits Per Second (bps) - a standard measure of data transmission speeds. A kilobit per second (Kbps) is one thousand bits per second. A megabit per second (Mbps) is one million bits per second.

Bit rate - Bps = Bytes per second, bps=bits per second. The digital equivalent if bandwidth, bit rate is measured in bits per second. It is used to express the rate at which the compressed bitstream is transmitted. The higher the bit rate, the more information that can be carried.

Blackburst (color-black) - A composite color video signal. The signal has composite sync, reference burst and a black video signal, which is usually at a level of 7.5 IRE (50 mV) above the blanking level.

Black level - A part of the video signal, close to the sync level, but slightly above it (usually 20 mV - 50 mV) in order to be distinguished from the blanking level. It electronically represents the black part of an image, whereas the white part is equivalent to 0.7 V from the sync level.

Blanking level - The beginning of the video signal information in the signal's waveform. It resides at a reference point taken as 0 V, which is 300 mV above the lowest part of the sync pulses. Also known as pedestal; the level of a video signal that separates the range that contains the picture information from the range that contains the synchronizing information.

Blooming - The defocusing of regions of a picture where brightness is excessive.

BNC - BNC stands for Bayonet-Neil-Concelman connector, and it is the most popular connector in CCTV and broadcast TV for transmitting a basic bandwidth video signal over a coaxial cable.

B-picture - Bidirectionally predictive coded picture; an MPEG term for a picture that is coded on CCTV broadcast TV for transmitting a basic bandwidth video signal over a coaxial cable.

Braid - A group of textile or metallic filaments interwoven to form a tubular structure that may be applied over one or more wires or flattened to form a strap.

Breakglass Station – a fire alarm box in which it is necessary to break a special element in order to operate the box.

Bridge - a network device used to connect two networks at the data link layer. Bridges are essentially unaware of the logical protocol address, although some bridges can block protocols by filtering their type codes or packet types.

Brightness - In NTSC and PAL video signals, the brightness information at any particular instant in a picture is conveyed by the corresponding instantaneous DC level of active video. Brightness control is an adjustment of setup (black level, black reference).

Broadband - a kind of network transmission that splits the bandwidth of a communications medium to support multiple communication channels. This technique is used by cable television.

Brouter - a network device that routes the routable protocols and -bridges the non-routable protocols. It essentially merges the functionality of bridges and routers.

Brownout - low line voltage which can cause misoperation of and possible damage to equipment.

Buffer - 1) temporary storage area, usually in RAM. The purpose of most buffers is to act as a holding area, enabling the CPU to manipulate data before transferring it to a device. 2) to move data into a temporary storage area.

Burglar Alarm System - an alarm system for detecting an unlawful structure entry.

Burglary Output – a panel output that is activated any time a burglary type zone is placed into alarm. The output turns off when the user disarms the area in which the alarm occurred.

Burst (color burst) - Seven to nine cycles (NTSC) or ten cycles (PAL) of sub-carrier placed near the end of horizontal blanking to serve as the phase (color) reference for the modulated color sub-carrier. Burst serves as the reference for establishing the picture color.

Bus - wires that connect the devices of an alarm system. DMP bus wires include both keypad bus and LX-Bus wires. Use 18 to 22 AWG, unshielded, 4-conductor wire on the DMP bus.

Bus Topology – the shape of the Local Area Network (LAN). All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology.

Butterfly Valve - a valve with a built-in tamper switch typically installed on a sprinkler system riser to allow the water to be shut off to only one section of the system.

Bypass - a manual zone shunt by a user that allows the panel to ignore any activity on the zone until it is reset back into the system. A user can bypass a zone from the user menu any time the zone is not armed. Also, a user can bypass a zone while arming the system. Used when a user wants to keep a door or window open or when a device is in need of service. See also Swinger Bypass.

Bypass Reports - a programming option that allows zone bypasses, resets, and force arm reports to be sent to a receiver.

Byte - A digital word made of 8 bits (zeros and ones).

C Back to Index

Cable equalization - The process of altering the frequency response of a video amplifier to compensate for high-frequency losses in coaxial cable.

Cable, shielded - cable completely enclosed in a metal sheath. Shielded wire is not recommended for the DMP bus.

Cable, twisted pair - conductors are paired (two wires are twisted around each other). Twisted pair wire is not recommended for the DMP bus.

CAD - Computer-aided design. This usually refers to a design of system that uses computer specialized software.

California State Fire Marshal (CSFM) - an agency that tests and approves fire alarm equipment for use in the state of California.

Cancel - see Abort and Abort Report.

Candela - the unit of luminous intensity in a given direction. One candela is commonly called one candle power.

Capacitance - the property of two or more objects that enables them to store electrical energy in an electrical field between them. The basic measurement is the Farad. Capacitance varies inversely with the distance between the objects, therefore the change of capacitance with relative motion is greater the nearer one object is to the other.

Card Access - a type of access control that uses cards or credentials to control area exit and entry.

Card Reader - a device that reads the information from an access card or credential. The reader then sends the information to the control panel to verify the information and then grant access if necessary.

Carpet Mat - a special pressure sensitive device made of opposing strips of thin metal separated by foam concealed under carpeting. A person stepping on the carpet mat, while its zone is armed, trips the alarm.

Carrier Sense Multiple Access with Collision Detection (CSMA/CD) - 1) a set of rules determining how transmissions respond when two devices attempt to use a carrier simultaneously (called a collision). 2) a cable access technique used by Ethernet that allows devices to gain access to a transmission medium by listening for the carrier presence. If a carrier is not detected, the data is transmitted. Each node is capable of detecting collisions and retransmitting as required.

CATV - Community antenna television.

C-band - A range of microwave frequencies, 3.7~4.2 GHz, commonly used for satellite communications.

CCD - Charge-coupled device. The new age imaging device, replacing the old tubes. When first invented in the 1970's, it was initially intended to be used as a memory device. Most often used in cameras, but also in telecine, fax machines, scanners, etc.

CCD aperture - The proportion of the total area of a CCD chip that is photosensitive.

CCIR - Committee Consultatif International des Radiocommunique or, in English, Consultative Committee for International Radio, which is the European standardization body that has set the standards for television in Europe. It was initially monochrome; therefore, today the term CCIR is usually used to refer to monochrome cameras that are used in PAL countries.

CCIR 601 - An international standard (renamed ITU 601) for component digital television that was derived from the SMPTE RP1 25 and EBU 3246E standards. ITU 601 defines the sampling systems, matrix values and filter characteristics for Y, Cr, Cb and RGB component digital television. It establishes a 4:2:2 sampling scheme at 13.5 MHz for the luminance channel and 6.75 MHz for the chrominance channels with eight-bit digitizing for each channel. These sample frequencies were chosen because they work for both 525-line 60 Hz and 625-line 50 Hz component video systems. The term 4:2:2 refers to the ration of the number of luminance channel samples to the number of chrominance channel samples; for every four luminance samples, the chrominance channels are each sampled twice. The D1 digital videotape format conforms to ITU 601.

CCIR656 - The international standard (renamed ITU 601) defining the electrical and mechanical interfaces for digital television equipment operating according to the ITU 601 standard. ITU 656 defines both the parallel and serial connector pinouts, as well as the blanking, sync and multiplexing schemes used in both parallel and serial interfaces.

CCTV - Close circuit television. A television system intended for only a limited number of viewers, as opposed to broadcast TV.

CCTV camera - A unit containing an imaging device that produces a video signal in the basic bandwidth.

CCTV installation - A CCTV system, or an associated group of systems, together with all necessary hardware, auxiliary lighting, etc., located at the protected site.

CCTV system - An arrangement comprising of a camera and lens with all ancillary equipment required for the surveillance of a specific protected area.

CCVE - Stands for closed circuit video equipment. An alternative acronym from CCTV.

CD - Compact disc. A standard of media as proposed by Philips and Sony, where music and data are stored in digital format.

CD-ROM - Compact disc read only memory. The total capacity of a CD-ROM when storing data is 640 MB.

CDS - Correlated double sampling. A technique used in the design of some CCD cameras that reduces the video signal noise generated by the chip.

Cell (Cellular) - a communication programming option that enables cellular transmissions with Cell-Miser™ call restrictions.

Cell-Miser™ - when Cell-Miser™ is selected in programming the panel restricts its cellular calls to zone alarms, ambush, line one trouble, abort, and recall test reports. Additionally:

• Delayed event reports can also be sent but only if the original cellular call was made to transmit one of the previously listed reports.
• Line 1 trouble is sent only once during each armed period.

Central Station - a remote monitoring station that receives alarms from alarm systems and informs the authorities.

Central Station Burglar Alarm System - an alarm system that transmits alarm, opening and closing, and other signals to a remote monitoring station called a central station. The alarm signals are retransmitted to the police department.

Central Station Fire Alarm System - a system or group of systems in which the operations of circuits and devices are transmitted automatically to, recorded in, maintained by, and supervised from a listed central station having competent and experienced servers and operators who, upon receipt of a signal, take such action as required by this code. Such service is to be controlled and operated by a person, firm, or corporation whose business is the furnishing, maintaining, or monitoring of supervised fire alarm systems.

Central Station Service - the use of a system or a group of systems in which the operations of circuits and devices at a protected property are signaled to, recorded in, and supervised from a listed central station having competent and experienced operators who, upon receipt of a signal, take such action as required by this code. Related activities at the protected property, such as equipment installation, inspection, testing, maintenance, and runner service are the central station responsibility or a listed fire alarm service local company. Central station service is controlled and operated by a person, firm, or corporation whose business is the furnishing of such contracted services or whose properties are the protected premises.

Certificated alarm system - alarm system where the Certificate issuing alarm company declares that Standards complying alarm service is provided. It is equivalent to a manufacturer whose name appears in a UL product directory choosing to place a UL Mark on a specific production product. A Certificated alarm system is subject to random audit by UL alarm system auditors to countercheck compliance, just as a product with a UL Mark is subject to random audit.

Certification - a systematic program using randomly selected follow-up inspections of the certificated systems installed under the program, which allows the listing organization to verify that a fire alarm system complies with all code requirements. A system installed under such a program is identified by the issuance of a certificated alarm system.

Certified Alarm Technician - a graduate of the Certified Alarm Technician (Level 1) program sponsored by the National Burglar & Fire Alarm Association and Security Industry Association. Graduates complete an overview of the electronic security industry.

CFA - Color filter array. A set of optical pixel filters used in single-chip color CCD cameras to produce the color components of a video signal.

CFM (Cubic Feet per Minute) - a unit volume measurement of the flow of a gaseous substance (such as air).

Channel Service Unit (CSU) - equipment used to terminate a digital circuit (such as DDS or T1) at the customer site. The unit also performs certain line-conditioning functions, ensures network compliance with FCC rules, and responds to zoneback commands from the central office.

Chime - A single-stroke or vibrating type audible notification appliance, which has a xylophone-type striking, bar, and/or tone.

Chip - An integrated circuit in which all the components are micro-fabricated on a tiny piece of silicon or similar material.

Chroma crawl - An artifact of encoded video, also known as dot crawl or cross-luminance, occurs in the video picture around the edges of highly saturated colors as a continuous series of crawling dots and is a result of color information being confused as luminance information by the decoder circuits.

Chroma gain (chroma, color, saturation) - In video, the gain of an amplifier as it pertains to the intensity if colors in the active picture.

Chroma key (color key) - A video key effect in which one video signal is inserted in place of areas of a particular color in another video signal.

Chrominance - The color information of a color video signal.

Chrominance-to-luminance intermodulation (crosstalk, cross-modulation) - An undesirable change in luminance amplitude caused by superimposition of some chrominance information on the luminance signal. Appears in a TV picture as unwarranted brightness variations caused by changes in color saturation levels.

CIE - Commission Internationale de l'Eclairage. This is the International Committee for Light, established in 1965. It defines and recommends light units.

Circuit – the path through which electrical energy flows. An alarm circuit begins with a voltage source negative terminal, continues through wire and protective devices contacts, and terminates at the same voltage source positive terminal.

Circuit Interface – a circuit component that interfaces initiating devices or control circuits, or both, notification appliances or circuits, or both, system control outputs, and other signaling line circuits to a signaling line circuit.

Cladding - The outer part of a fiber optics cable, which is also a fiber but with a smaller material density than the center core. It enables a total reflection effect so that the light transmitted through the internal core stays inside.

Clamping (DC) - The circuit or process that restores the DC component of a signal. A video clamp circuit, usually triggered by horizontal synchronizing pulses, re-establishes a fixed DC reference level for the video signal. A major benefit of a clamp is the removal of low-frequency interference, especially power line hum.

Class A Circuit (Zone) – NFPA Style D - a type of 4-wire alarm circuit used to detect an alarm or line fault. The circuit allows alarm condition reporting even when a trouble condition has occurred. Two conductors run from the alarm panel, and two return. A single break does not prevent the alarm signal reception, but does initiate a trouble signal. Fire protection systems require alarm operation even when a single break or a single ground faults exists on the circuit.

Class B Circuit (Zone) - NFPA Style A - a 2-wire alarm circuit in which two wires travel from an alarm panel and connect with one or more sensors and may or may not return to the panel. A single break prevents the reception of an alarm signal from any point beyond the break, and also initiates a trouble signal.

Client – a process (program or routine) or entity (person, LAN) that employs the services of servers.

Client/server - the interaction of software processes that function in a cooperative manner. Clients make requests of servers.

Clipping level - An electronic limit to avoid overdriving the video portion of the television signal.

Closing Check – a programming option that enables the panel to verify that all areas in a partition are armed after the scheduled time. If the closing check finds any areas disarmed past the scheduled time, the keypad selected to display system trouble status emits a steady beep and displays CLOSING TIME! If you also select Area Schedules, the appropriate area name displays followed by - LATE. Silence the keypad steady beep by pressing any top row Select key. If the system is not armed or the schedule is not extended within ten minutes, a no closing report is sent to the central station receiver. If the area was disarmed outside of any schedule, the closing check sequence occurs one hour after the area was disarmed.

Closing Code - a programming option that requires the entry of a user code when arming the system.

Closing Wait – a programming option that provides for the panel to display a message on the keypad and delay arming the system until the closing report has been acknowledged by the central station receiver.

C-mount - The first standard for CCTV lens screw mounting. It is defined with the thread if 1” (2.54mm) in diameter and 32 threads/inch, and the back flange-to-CCD distance of 17.526mm (0.69”). The C-mount description applies to both lenses and cameras. C-mount lenses can be put on both C-mount and CS-mount cameras; only in the latter case an adaptor is required.

CMYK - A color encoding system used by printers in which colors are expressed by the “subtractive primaries” (cyan, magenta and yellow) plus black (called K). The black layer is added to give increased contrast and range on printing presses.

Coaxial Cable – a cable containing two conductors, one inside the other. Coaxial cables, or more commonly called coax, are used in thickwire and thinwire Ethernet and IBM terminal connections.

Code 3 - See Temporal Code. See also Bell Action.

CODEC - Code/Decode. An encoder plus a decoder is an electronic device that compresses and decompresses digital signals. CODECs usually perform A/D and D/A conversion.

Code Change Reports - a programming option that allows code additions, changes, and deletions to be sent to a receiver.

Coded - an audible or visible signal conveying several discrete bits or units of information. Notification signal examples are impact-type appliance numbered strokes and visible appliance numbered flashes.

Coded System - a system in which not less than three rounds of coded alarm signals are transmitted, after which the alarm may be manually or automatically silenced. Generally used with McCulloh circuit systems.

Cold Solder Joint - a solder joint in which insufficient heat has been applied, resulting in a bad connection. The joint exhibits a grayish, dull appearance while good (hot) joints are shiny.

Cold Water Pipe Ground - the connection of a designated point of an electronic device to a cold water pipe to ensure a good earth ground.

Collision - the condition that results when two network devices transmit at nearly the same time. The transmissions collide, making the data unusable.

Color bars - A pattern generated by a video test generator, consisting of eight equal width color bars. Colors are white (75%), black (7.5% setup level), 75% saturated pure colors red, green and blue, and 75% saturated hues of yellow, cyan and magenta (mixtures of 2 colors in 1:1 ratio without third color).

Color carrier - The sub-frequency in a color video signal (4.43 MHz for PAL) that is modulated with the color information. The color carrier frequency is chosen so its spectrum interleaves with the luminance spectrum with minimum interference.

Color difference signal - A video color signal created by subtracting luminance and/or color information from one of the primary color signals (red, green or blue). In the Beta cam color difference format, for example, the luminance (Y) and color difference components (R-Y and B-Y) are derived as follows -

• Y = 0.3 Red + 0.59 Green + 0.11 Blue
• R-Y = 0.7 Red - 0.59 Green - 0.11 Blue
• B-Y = 0.89 Blue - 0.59 Green - 0.3 Red

The G-V color difference signal is not created because it can be reconstructed from the other three signals. Other color difference conventions include SMPTE, EBU-N1 0 and MII. Color difference signals should not be referred to as component video signals. That term is resaved for the RGB color components. In informal usage, the term “component video” is often used to mean color difference signals.

Color field - In the NTSC system, the color sub-carrier is phase-locked to the line so that on each consecutive line, sub-carrier phase is changed 180 degrees with respect to the sync pulses. In the PAL system, color sub carrier phase moves 90 degrees every frame. In NTSC this creates four different filed types, while in PAL there are eight. In order to make clean edits, alignment of color field sequences from different sources is crucial.

Color frame - In color television, four (NTSC) or eight (PAL) properly sequenced color fields compose one color frame.

Color phase - The timing relationship in a video signal that is measured in degrees and keeps the hue of a color signal correct.

Color sub-carrier - The 3.58 MHz signal that carries color information. This signal is superimposed on the luminance level. Amplitude of the color sub-carrier represents saturation and phase angle represents hue.

Color temperature - Indicates the hue of the color. It is derived from photography where the spectrum of colors is based upon a comparison of the hues produced when a black body (as in physics) is heated from red through yellow to blue, which is the hottest. Color temperature measurements are expressed in Kelvin.

Comb filter - An electrical filter circuit that passes a series of frequencies and rejects the frequencies in between, producing a frequency response similar to the teeth of a comb. Used on encoded video to select the chrominance signal and reject the luminance signal, thereby reducing cross-chrominance artifacts or conversely, to select the luminance signal and reject the chrominance signal, thereby reducing cross-luminance artifacts. Introduced in the S-VHS concept for a better luminance resolution.

Combination Detector - a device that either (a) responds to more than one of the fire signatures or (b) employs more than one operating principle to sense any one of these signatures. Typical examples are (a) a combination of a heat detector with a smoke detector, or (b) a combination rate-of-rise and fixed temperature heat detector.

Combination Fire Alarm and Guard’s Tour Box – a manually operated box for separately transmitting a fire alarm signal and a distinctive guard patrol tour supervisory signal.

Combination System - a protected premises fire alarm system for fire alarm, supervisory, or watchman service whose components can be used in whole or part in common with a non-fire-emergency signaling system, such as a paging system, a musical program system, HVAC control system, or a process monitoring system, without degradation of, or hazard to, the fire alarm system.

COMMAND key - a keypad function key used to step ahead through options in the panel programmer or user menu. Pressing the COMMAND key allows you to go forward and through each menu section step. As you go through the options, the keypad displays any current selections already stored in panel memory. The COMMAND key is also used to enter information into panel memory, such as phone numbers or zone names, by pressing the key after entering the information and it displays correctly on the keypad.

Command Processor™ - the trademarked name for DMP control/communicator alarm panels.

Common Area - a unique DMP programming option that allows specification of one or more areas within a partition or area to arm automatically when all other areas are armed. Alternately, common areas disarm when any area in the same partition or area is disarmed. Common areas are ideal for lobbies, storage rooms, or other areas shared by users.

Communication Port (COM port) - 1) a serial port on a computer designed for communicating. DMP uses this port to connect to a receiver, or direct connect to a panel or to a network. 2) A connection on a computer where a serial device can be plugged. 3) A serial communication port that supports RS-232 standard communication.

Communication type - a programming option that specifies the communication method the panel uses to report events to DMP receivers or non-DMP receivers. Note - All formats are not available for all panels. Consult a programming guide for availability.

• DD - Digital Dialer communication to DMP receivers.
• MPX - Multiplex communication format to DMP receivers.
• M2E - Radionics Modem IIe communication format to non-DMP receivers.
• NET - Asynchronous communication transmitted over a network to a DMP SCS-1/SCS-1R receiver or Remote Link™.
• CID - Ademco Contact ID communication format to non-DMP receivers.
• 4-2 - A hexadecimal communication format to non-DMP receivers.
• DNET - Data network connection to a DMP SCS-1/SCS-1R receiver following multiplex rules.
• HST - See NET.

Communications Channel - a circuit or path connecting a subsidiary station(s) to a supervising station(s) over which signals are carried.

Communicator Delay - see Transmit Delay.

Compatible - equipment that interfaces mechanically or electrically together as manufactured without modification.

Compatibility Listed - a specific listing process that applies only to 2-wire devices (such as smoke detectors) that are designed to operate with certain control equipment.

Composite Sync - A signal consisting of horizontal sync pulses, vertical sync pulses and equalizing pulses only, with no-signal reference level.

Composite video signal - A signal in which the luminance and chrominance information has been combined using one of the coding standards NTSC, PAL, SECAM, etc.

Concave lens - A lens that has negative focal length; i.e., the focus is virtual and it reduces the objects.

Conduit - a pipe or tube of varying materials, primarily metal or plastic, used to carry wiring.

Contact ID (CID) - a panel-reporting format developed by Ademco that allows panels to send reports to a receiver in DTMF format. A Contact ID report is made up of 18 DTMF digits.

Contact Switch - a device used to protect doors, windows, and other openings containing a sealed metallic switch held in a closed position by a companion magnet. The contact is usually attached to the fixed frame of a door or a window while the magnet is attached to the moving part of the door or window. If the magnet is moved away from the contact while its zone is armed an alarm condition occurs.

Contrast - A common term used in reference to the video picture dynamic range, i.e., the difference between the darkest and the brightest parts of an image.

Control Panel or Control - see Command Processor™.

Convex lens - A convex lens has a positive focal length, i.e., the focus is real. It is usually called magnifying glass, since it magnifies the objects.

CPU - Central processing unit. A common term used in computers.

Crawlspace - the area under a building used for ductwork and plumbing where alarm installers can also run wiring.

Crimp Connector - a barrel-shaped connector that holds two wires together when pressed around the wires.

CRO. Cathode ray oscilloscope (see Oscilloscope)

Crosstalk - A type of interference of undesired transmission of signals from one circuit into another circuit in the same system. Usually caused by unintentional capacitance (AC coupling).

Cross-Zone Time - the amount of time programmed into the panel during which armed cross-zoned zones must trip before an alarm report is sent to the central station. Cross-zone time can be from 4 to 250 seconds.

Cross Zoning – a zone characteristic that requires the zone to trip twice, or a second cross-zoned zone to trip, within a programmed amount of time before an alarm report is sent to the central station. An example of cross zoning would be two interior PIRs. One PIR might trip due to an environmental occurrence but an alarm report would not be sent until the other PIR is also tripped or the first PIR restores and then trips again. If neither zone trips before the programmed cross-zone time expires, only a zone fault report is sent to the central station. Cross zoning reduces false alarms by requiring two zone trips to send an alarm report. See also the DMP Application Note Understanding Cross Zoning (LT-2000).

CS-Mount - A newer standard for lens mounting. It uses the same physical thread as the C-mount, but the back flange-to-CCD distance is reduced to 12.5mm in order to have the lenses made smaller, more compact and less expensive. CS-mount lenses can only be used on CS-mount cameras.

CS-to-C-mount adaptor - An adaptor used to convert a CS-mount camera to C-mount to accommodate a C-mount lens. It looks like a ring 5 mm thick, with a male tread on one side and a female on the other, with 1” diameter and 32 threads/inch. It usually comes packaged with the newer type (CS-mount) of cameras.

Current - the movement of electron through a conductor. Measured in Amperes (Amp).

Cutoff Output - a panel programming option that allows you to specify individual on-board outputs to turn off after a programmed time period. See Cutoff Time.

Cutoff Time - a programming option that specifies how long an output remains activated. The programmable range is in 1-minute increments.

CVBS - Composite video bar signal in broadcast television this refers to the video signal, including the color information and syncs.

D Back to Index

D/A (also DA) - Opposite to A/D, i.e., digital to analog conversion.

damper - a valve or plate regulating the flow of air or other fluid.

Dark current - Leakage signal from a CCD sensor in the absence of incident light.

Dark noise - Noise caused by the random (quantum) nature of the dark current.

DAT (digital audio tape) - A system developed initially for recording and playback of digitized audio signals, maintaining signal quality equal to that of a CD. Recent developments in hardware and software might lead to a similar inexpensive system for video archiving, recording and playback.

Data - information, specifically in digital systems, that is operated on and produces an output, in contrast to commands or control signals.

Data Communications Equipment (DCE) - a type of network component that facilitates the sending of data such as a modem or multiplexer.

Datagram - a packet of data unique to a specific protocol. Datagrams are placed within network frames for delivery over the network.

Data Service Unit (DSU) - a component of customer premises equipment used as an interface to a digital circuit. For example - DDS or T1. Combined with a Channel Service Unit (CSU), it converts a customer’s data stream to bipolar format for transmission.

Data Terminal Equipment (DTE) - a type of network component such as a CRT (monitor) or a computer workstation.

Day Zone - a zone type that buzzes the keypad and provides a trouble report to the central station if the zone is tripped while its area is disarmed and an alarm if the zone is tripped while the area is armed. This is typically used with window foil, emergency zones, or other types of protection that needs constant supervision but not always an alarm. The keypad buzzer initiated by a day zone can be silenced by pressing any top row select key.

dB - Decibel. A logarithmic ratio in two signals or values usually refers to power, but also voltage and current. When power is calculated the logarithm is multiplied by 10, while for current and voltage by 20.

DBS - Direct broadcast satellite. Broadcasting from a satellite directly to a consumer user, usually using a small aperture antenna.

DC - direct current.

DCID 6/9 - US Government manual describing the physical security standards for Sensitive Compartmented Information Facilities (SCIF). The document covers the construction and protection of facilities for storing, processing, and discussing Sensitive Compartmented Information. Effective date for this document is 11/18/02.

DCT - Discrete cosine transform. Mathematical algorithm used to generate frequency representations of a block of video pixels. The DCT is an invertible, discrete orthogonal transformation between time and frequency domain. It can be either forward discrete cosine transform (FDCT) or inverse discrete cosine transform (IDCT).

DD (Digital Dialer) - a programming option for the panel to use the DMP Serial 3 format for communication to the SCS-1/SCS-1R central station receiver.

DDMX - A communication option in the 1912XR Command Processor panel that allows the panel to communicate to the central station as a digital dialer during disarmed periods but then switch automatically to multiplex communication when the last area in the system is armed.

Dead Short - a short circuit having extremely low (or virtually no) resistance.

Dealer - an alarm company that leases or sells alarm systems.

Decibel - a measurement used to compare measured levels of sound energy (intensity) to the apparent level detected by the human ear, expressed as a logarithmic ratio. Abbreviation is dB.

Decoder - A device used to recover the component signals from a composite (encoded) source.

Defer Test Time - a programming option that allows the panel to defer sending in a scheduled test report if it has already communicated with the central station receiver within the time period entered into the test frequency option. See Test Frequency.

Degauss - To demagnetize.

Delay line - An artificial or real transmission line or equivalent device designed to delay a wave or signal for a specific length of time.

Delay Reports - a programming option under Events Manager that provides for all non-alarm reports to be held in panel memory until the event buffer is nearly full or until the next panel communication with the receiver.

Delay Zone - see Exit Zone.

Deluge Sprinkler System - a sprinkler system having open sprinklers, the water to which is controlled by a manually or automatically operated valve that allows heavy concentrations of water to deluge the area.

Demodulator - A device that strips the video and audio signals from the carrier frequency.

Depth of field - The area in front of and behind the object in focus that appears sharp on the screen. The depth of filed increases with the decrease of the focal length, i.e., the shorter the focal length the wider the depth of field. The depth of field is always wider behind the objects in focus.

Derived Channel - a signaling line circuit that uses the public switched network local leg as an active multiplex channel, while simultaneously allowing that leg to be use for normal telephone communications.

Detector - a device installed at a location in a security system that is designed to detect an intruder, rise of temperature, presence of smoke, etc.

Device - any keypad, expander, or point addressable module that requires an address on the keypad or LX-Bus.

Device Fail Output – a programming option that provides for the specified output to turn on any time an addressed device fails to respond to panel polling. The output turns off when all programmed devices respond to polling.

DHCP - Short for Dynamic Host Configuration Protocol, a protocol for assigning dynamic IP addresses to devices on a network. With dynamic addressing, a device can have a different IP address every time it connects to the network. In some systems, the device IP address can even change while connected. DHCP also supports a mix of static and dynamic IP addresses. Dynamic addressing simplifies network administration because the software keeps track of IP addresses rather than requiring an administrator to manage the task. This means that a new computer can be added to a network without the hassle of manually assigning it a unique IP address. Many IPSs use dynamic IP addressing for dial-up users.

Dielectric - An insulating (nonconductive) material.

Differential gain - A change in sub-carrier amplitude of a video signal caused by a change in luminance level of the signal. The resulting TV picture will show a change in color saturation caused by a simultaneous change in picture brightness.

Differential phase -The change in the sub-carrier phase of a video signal caused by a change inn the luminance level of the signal. The hue of colors in a scene change with the brightness of the scene.

Digital Alarm Communicator Receiver (DACR) - a system component located in the supervising station that accepts and displays signals from the DACT sent over the public switched telephone system.

Digital Alarm Communicator System (DACS) - a system in which signals are transmitted from a DACT located at the protected premises through the public switched telephone network to a DACR located at the supervising station.

Digital Alarm Communicator Transmitter (DACT) - a system component at the protected premises to which initiating devices or groups of devices are connected. The DACT seizes the connected telephone line, dials a pre-selected number to connect to a DACT in the supervising station, and transmits signals indicating the initiating device status change.

Digital Communicator (Digital Dialer) - a device that transmits alarm signals and other information to a central station using the existing customer phone line. To transmit an alarm, the communicator seizes the customer’s phone line and electronically dials the central station receiver. When the receiver answers, the communicator sends a message in the form of a sequence of tones. A minicomputer in the receiver accepts and acknowledges the message. It then prints out the information for display to the operator.

Digital disc recorder - A system that allows recording of video images on a digital disc.

Digital signal -An electronic signal where every different value from the real-life excitation (sound, light) has a different value of binary combinations (words) that represent the analog signal.

DIN - Deutsche Industrie-Normen. Germany's standard.

Direct-Connect Alarm System - an alarm system connected to a police or fire department.

Direct Current (DC) - electrical current that travels in only one direction and has negative and positive polarity. It may or may not have an AC ripple component. DC sources that are unfiltered should be referred to as full-wave or half-wave rectified AC.

Direct Wire - a dedicated leased telephone line from the subscriber premises directly to a central station.

Disarm - to turn off the burglary protection in an area using a keypad, keyswitch, or remote programmer.

Disarmed Rings - the number of rings the panel counts before answering the phone line when any system areas are disarmed.

Disk - A flat circular plate, coated with a magnetic material, on which data may be sorted by selective magnetization of portions of the surface. May be a flexible floppy disk or rigid hard disk. It could also be a plastic compact disc (CD) or digital video disk (DVD).

Display Events - a user menu option that allows authorized users to view a record of events that occurred on the system. The panel stores in memory all alarms, troubles, and restorals as well as other options.

Distortion -Non- proportional representation of an original.

DMD - Digital micro-mirror device - A new video projection technology that uses chips with a large number of miniature mirrors, whose projection angle can be controlled with digital precision.

Door Access - a feature that allows a user to enter their code number and cause an internal Form C relay to activate and release an electric door strike or magnet. A door access report containing the keypad address and user number can also be sent to the central station.

Door Prop - a programming option of the XR200/485/XR500 Series/XR2500F that sends an “open” message to the keypads and a “zone fault” to a receiver when a door is left open past the specified amount of time.

Door Status Switch (DSS) - a switch used to monitor whether a door is in an opened or closed position.

DOS - Disk operating system. A software package that makes a computer work with its hardware devise such as hard drive, floppy drive, screen, keyboard, etc.

Dot pitch - The distance in millimeters between individual dots on a monitor screen. The smaller the dot pitch the better, since it allows for more dots to be displayed and better resolution. The dot pitch defines the resolution of a monitor. A high-resolution CCTV or computer monitor would have a dot pitch of less than 0.3mm.

Double Pole, Double Throw (DPDT) - a switch or relay output contact (form C) that has two separate switches operating simultaneously, each with a normally open and normally closed contact and a common connection. This form is used to make and break two separate circuits.

Drop-frame time code - SMPTE time code format that continuously counts 30 frames per second, but drops two frames from the count every minute except for every tenth minute (drops 108 frames every hour) to maintain synchronization of time code with clock time. This is necessary because the actual frame rate of NTSC video is 29.94 frames per second rather than an even 30 frames.

Dry contacts - generally, relay contacts that are isolated from the circuit board and power supply and have no voltage applied to them. They can be opened, closed, or a combination. See Form “A” Contacts, Form “B” Contacts, and Form “C” Contacts.

Dry-Pipe Automatic Sprinkler System - an automatic sprinkler system in which piping from the alarm check valve to each sprinkler head contains air under pressure. This pressure holds the alarm valve closed, keeping water out of the system. This type of system is used where there is danger of water freezing if allowed to remain in the system piping.

DSP - Digital signal processing. It usually refers to the electronic circuit section of a device capable of processing digital signals.

Dual Reporting - a method of sending the same signals to two separate receivers. An example would be to send alarms and openings/closings to receiver 1 and receiver 2.

Dual-Tone Multiple-Frequency (DTMF) - a feature that enables touch-tone dialing.

Dubbing - Transcribing from one recording medium to another.

Duct - a passageway made of sheet metal or other suitable material not necessarily leak-tight, used for conveying air or other gas at low pressures.

Duct type smoke detector - a device located within a duct, protruding into a duct, or located outside a duct that detects visible or invisible particles of combustion flowing within the duct. Actuation of the device may allow operation of certain control functions.

Duplex - simultaneous, independent, 2-way data transmission.

Duress - see Ambush.

DV-Mini - Mini digital video. A new format for audio and video recording on small camcorders, adopted by the majority of camcorder manufacturers. Video and sound are recorded in a digital format on a small cassette (66x48x12mm) superseding S-VHS and Hi 8 quality.

D-VHS - A new standard proposed by JVC for recording digital signals on a VHS video recorder.

Dynamic Address - Generally refers to a computer location address that is variable. The opposite of dynamic is static.

Dynamic range - The difference between the smallest amount and the largest amount that a system can represent.

E Back to Index

Earth Ground - the grounding of a device by means of a copper conductor connected to a copper clay rod in the Earth.

EBU - European Broadcasting Union.

EIA - Electronics Industry Association, which has recommended the television standard used in the U.S., Canada and Japan, based on 525 lines interlaced scanning. Formerly known as RMA or RETMA.

Encoder - A device that superimposes electronic signal information on other electronic signals.

Encryption - The rearrangement of the bit stream of a previously digitally encoded signal in a systematic fashion to make the information unrecognizable until restored on receipt of the necessary authorization key. This technique is used for securing information transmitted over a communication channel with the intent of excluding all other than authorized receivers from interpreting the message. Can be used for voice, video and other communications signals.

ENG camera - Electronic News Gathering camera. Refers to CCD cameras in the broadcast industry.

EPROM - Acronym for Erasable Programmable Read-Only Memory, and pronounced ee-prom. EPROM is a special type of memory that retains its contents until it is exposed to ultraviolet light. The ultraviolet light clears its contents, making it possible to reprogram the memory. To write to and erase an EPROM, you need a special device called a PROM programmer or PROM burner.

Egress - a programming option that allows individual access doors to be assigned to detect anti-passback violations. See also Anti-Passback.

Electric Door Strike - an electric door locking device (usually solenoid-operated) that unlocks the door when electrical power is applied to it. A fail-safe configuration operates in reverse; that is, it is normally locked when power is applied and unlocked when power is interrupted.

Electromagnet - a coil of wire, usually wound on an iron core that produces a strong magnetic field when current is sent through the coil.

Electromagnetic - pertaining to the relationship between current flow and magnetic fields.

Electromagnetic Interference (EMI) - impairment of the reception of a wanted electromagnetic signal by an electromagnetic disturbance which can be caused by lightning, radio transmitters, power line noise, and other electrical devices.

Electronics Industry Association (EIA) - an electronics industry trade association that formulates technical standards, disseminates marketing data, and maintains contact with government agencies.

Emergency Release - an optional lock feature that provides a means of overriding the lock and retracting the bolt in an emergency. It can be operated either mechanically or electrically.

Emulation - see Terminal Emulation.

End-of-Line Device (EOL)– a device such as a resistor (EOLR) placed at the end of a Class B wire zone to maintain supervision.

End-of-Line Power Supervision Relay - a device used to supervise power (usually for 4-wire smoke detectors) and installed within the last device on the zone.

Entry Delay - the length of time programmed into the system during which the user can enter the premises through an exit zone (usually a front door) and disarm the system.

Entry Output - a specified output on a panel that is turned on at the start of the entry delay time. The output is turned off when the area is disarmed or the entry delay time expires.

Entry Zone - a zone type that allows the user a short amount of time to enter and exit while the system is armed without setting off an alarm.

Equalizer - Equipment designed to compensate for loss and delay frequency effects within a system. A component or circuit that allows for the adjustment of a signal across a given brand.

Ethernet - a LAN cabling system originally developed by Xerox, Intel, and Digital. Ethernet has a bandwidth of 10 Mbps and uses the CSMA/CD access method.

Events - system activity that generates messages to the reporting device.

Events Manager - a programming option that specifies when non-alarm reports are sent to the receiver. Selecting this option does not affect zone alarm, zone trouble, zone restoral, supervisory, or serviceman reports. Closing reports are not delayed if the closing wait option is enabled.

Exit Alarm - an alarm that occurs when a zone is still faulted at the end of the exit delay time. This usually occurs when the door through which the user exited does not close all the way before the programmed exit time expired.

Exit Button - a button serving as an electrical switch that releases a lock on an exit door when depressed. Also called a Request to Exit (REX) button.

Exit Delay Time - the length of time programmed into the system during which the user can exit the premises through an exit zone (usually a front door) and disarm the system.

Exit Output - a specified panel output that is turned on any time an exit delay time starts in any area of the system. The output is turned off when the exit delay time expires or when the arming has been stopped.

Exit Zone - a zone type usually assigned to a perimeter door that allows users a programmable amount of time to enter and exit while the system is armed without setting off an alarm.

Extended Binary Coded Decimal Interchange Code (EBCDIC) - a coding system that uses eight bits of data to represent alphanumeric characters and control sequences. Used by IBM mainframes.

External synchronization - A means of ensuring that all equipment is synchronized to the one source.

F Back to Index

Factory Defaults - a panel programmer function that allows you to quickly turn programming parameters back to their factory default setting.

Factory Mutual (FM) - an agency sponsored by insurance providers that tests and approves various alarm and consumer products.

Fail-Safe Lock - an electric lock that automatically unlocks when power is removed from the lock.

Fail-Secure Lock - an electric lock that automatically locks when power is removed from the lock.

False Alarm - an alarm signal initiated without the presence of an emergency. This term is generally used to describe an unwanted alarm condition. A false alarm report is sent by the panel due to a user error, environmental activation, or malfunction of a security device installed in the system. False alarms can be controlled by thoroughly training all users and ensuring that equipment is installed according to the manufacturer recommendations.

False Alarm Reduction - DMP features designed to reduce, if not eliminate, the occurrence of false alarms. The False Alarm Reduction features include - Cross-Zoning, Transmit Delay, Abort Reports, and Exit Error.

Fault - a report that is sent to the central station receiver whenever a fire verify or cross zoned zone is tripped once but does not trip a second time to cause an alarm.

FCC - Federal Communications Commission (U.S.)

Feature Key - a unique alphanumeric code used to enable a specific feature on an XR500 Series panel.

Federal Communications Commission (FCC) - board of five commissioners having the power to regulate all electrical communications systems originating in the United States, including radio, television, facsimile, telegraph, telephone, and cable systems.

FFT - Fast Fourier Transformation.

Fiber Distribution Data Interface (FDDI) - a 100 Mbps LAN technology that uses a token-passing access method. FDDI uses dual fiber-optic rings.

Fiber optics - A technology designed to transmit signals in the form of pulses of light. Fiber optic cable is noted for its properties of electric isolation and resistance of electrostatic and electromagnetic interference.

Field - Refers to one-half of the TV frame that is composed of either all odd or even lines. In CCIR systems each field is composed of 625/2 = 312.5 lines, in EIA systems 525/2 = 262.5 lines. There are 50 fields/second in CCIR/PAL, and 60 in the EIA/NTSC TV system.

File Server - in Local Area Networks, a station dedicated to providing file and mass storage services to the other stations on the network.

File Transfer Protocol (FTP) - a service layer protocol common in the TCP/IP world that is used to copy files between network devices.

Film recorder - A device for converting digital data into film output. Continuous tone recorders produce color photographs as transparencies, prints or negatives.

Fingerprint Reader - a biometric access control device that identifies users by scanning fingerprints. Can also be used in conjunction with a proximity reader.

Fire Alarm Control Unit (panel) - a system component that receives inputs from automatic and manual fire alarm devices and may supply power to detection devices. The control unit may also provide transfer of power to the notification appliances and transfer condition of relays or devices connected to the unit.

Fire Alarm Output - a specified output on a panel that is turned on any time a fire type zone is placed into an alarm condition. The output is turned off using the sensor reset option in the user menu while no additional fire type zones are in alarm.

Fire box - see Manual Pull Station.

Fire Command™ Keypads - family of DMP keypads designed specifically for use on fire systems.

Fire Trouble Output - a specified output on a panel that turns on any time a fire type zone or any system monitor is placed into a trouble condition, or when a supervisory type zone is placed into an alarm or trouble condition. The output turns off when all fire and supervisory type zones are restored to normal.

Fire Verification - typically used on smoke detector zones to provide a reset of the panel switched auxiliary power or power supply (from where the smoke detectors are powered) and a delayed length of time during which the detector must trip again before an alarm initiates.

Fire Verify - a zone type typically used with smoke detectors that provides a reset, after a fire alarm, of the panel’s switched auxiliary power and 2-wire smoke detector zones and a delayed length of time during which the detector must trip again before an alarm is initiated.

Fire Wall - 1) a fire resistant wall designed to prevent the horizontal spread of a fire into adjacent areas. 2) A system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.

Firmware - software (programs or data) that has been written onto read-only memory (ROM). Firmware is a combination of software and hardware. ROMs, PROMs and EPROMs that have data or programs recorded on them are firmware.

Fixed focal length lens - A lens with a predetermined fixed focal length, a focusing control and a choice of iris functions.

Fixed Temperature Heat Detector - a thermal sensing device rated at specific temperature to detect and provide signal output.

Flame Detector - a device that detects the infrared, ultraviolet, or visible radiation produced by a fire.

Flicker - An annoying picture distortion, mainly related to vertical syncs and video fields display. Some flicker normally exists due to interlacing; more apparent in 50 Hz systems (PAL). Flicker shows also when static images are displayed on screen such as computer-generated text transferred to video. Poor digital image treatment, found in low-quality system converts (going from PAL to NTSC and vice versa), creates an annoying flicker on the screen. There are several electronic methods to minimize flicker.

Flow Control - the process of adjusting the flow of data from one device to another to ensure that the receiving device can handle all of the incoming data. This is particularly important where the sending device is capable of sending data much faster than the receiving device can receive it.

Flowswitch - see Waterflow Switch.

F-number - In lenses with adjustable irises, the maximum iris opening is expressed as a ratio (focal length of the lens) / (maximum diameter of aperture). This maximum iris will be engraved on the front ring of the lens.

Focal length - The distance between the optical center of a lens and the principal convergent focus point.

Focusing control - A means of adjusting the lens to allow objects at various distances from the cameras to be sharply defined.

Foot-candela - An illumination light unit used mostly in American CCTV terminology. It equals ten times (more precisely, 9.29) of the illumination value in luxes.

Force Arm - used with the auto arm feature or a keyswitch, this arming option allows the panel to force arm the system and ignore all faulted zones. Zones force armed in a faulted condition are capable of restoring and reporting an alarm if tripped. A force armed zones report is sent to the central station receiver if the bypass reports option is programmed as YES.

Form “A” Contacts - single-throw contacts that are normally open. See Normally Open Circuit.

Form “B” Contacts - single-throw contacts that are normally closed. See Normally Closed Circuit.

Form “C” Contacts - a dry contact, single-pole double-throw (SPDT) relay that provides one common, one normally open, and one normally closed connection. When activated, the normally open side shorts to the common while the normally closed side opens.

Fourier Transformation - Mathematical transformation of time domain functions into frequency domain.

Four-Wire Smoke Detector - a smoke detector that initiates an alarm condition on two separate wires (initiating zone) apart from the two power leads.

Frame - a data link structure for conveying information over a transmission medium.

Frame store - An electronic device that digitizes a TV frame (or TV files) of a video signal and stores it in memory. Multiplexers, fast scan transmitters, Quad compressors and even some of the latest color cameras have built-in framestores.

Frame switcher - Another name for a simple multiplexer, which can record multiple cameras on a single VCR (and play back any camera in full screen) but does not have a mosaic image display.

Frame synchronizer - A digital buffer that, by storage and comparison of sync information to a reference and timed release of video signals, can continuously adjust the signal for any timing errors.

Frame transfer (FT) - Refers to one of the three principles of charge transfer in CCD chips. The other two are interline and frame-interline transfer.

Frame-interline transfer (FIT) - Refers to one of the few principles of charge transfer in CCD chips. The other two are interline and frame transfer.

Frequency - the number of complete operations or cycles that take place within a given period of time. The basic unit of frequency is the Hertz (Hz), which is one cycle per second.

Frequency modulation (FM) - Modulation of sine wave or carrier by varying its frequency in accordance with amplitude variations of the modulating signal.

Front porch - The blanking signal portion that lies between the end of the active picture information and the leading edge of horizontal sync.

Full Duplex - a multiplex system that can simultaneously transmit in both directions on one transmission line.

Fully Armed - a condition on the system where all zones and areas are in an armed state.

Fully Supervised Zone - a zone that reports a short, open or ground to an alarm receiver.

G Back to Index

Gain - increased signal power, usually the result of amplification.

Gamma - A correction of the linear response of a camera in order to compensate for the monitor phosphor screen nonlinear response. It is measured with the exponential value of the curve describing the non-linearity. A typical monochrome monitor's gamma is 2.2, and a camera needs to be set to the inverse value of 2.2 (which is 0.45) for the overall system to respond linearly (i.e., unity).

Gamut - The range of voltages allowed for a video signal, or a component of a video signal. Signal voltages outside of the range (i.e., exceeding the gamut) may lead to clipping, crosstalk or other distortions.

Gang Box - electrical outlet box made by joining two or more boxes together to form a larger box.

Gateway - a device (or software process) that translates entire protocol stacks.

Gauge - a measure of the diameter of wire. See American Wire Gauge.

Gel Cell Battery - a rechargeable electrolyte battery commonly used as a backup power source in alarm systems. Gel Cell Batteries CANNOT be used on DMP equipment.

General Alarm - a term usually applied to the simultaneous operation of all the audible and visible alarm notification appliances on a system to indicate the need for building evacuation.

Gen-lock - A way o locking the video signal of a camera to an external generator of synchronization pulses.

GHz - GigaHertz. One billion cycles per second.

GB - Gigabyte. Unit of computer memory consisting of about one thousand million bytes (a thousand megabytes). Actual value is 1,073,741,824 bytes.

Glassbreak Detector - a device that senses an attack on a glass surface.

GND - Ground (electrical).

Graphic Annunciator - a board that has special graphics to delineate alarm or sensor locations.

Gray scale - A series of tomes that range from true black to true white, usually expressed in 10 steps.

Ground - an electrical connection to the Earth. See Earth Ground.

Ground Fault - 1) a loss of a ground connection. 2) A short circuit to ground.

Ground loop - An unwanted interference in the copper electrical signal transmissions with shielded cable, which is a result of ground currents when the system has more than one ground. For example, in CCTV, when we have a different earthing resistance at the camera, and the switcher or monitor end. The induced electrical noise generated by the surrounding the electrical equipment (including mains) does not discharge equally through the two earthings (since they are different) and the induced noise shows up on the monitors as interference.

Ground Start - a method of accessing a dial tone where the panel momentarily shorts the ring side of the telephone circuit to the ground. Most phones use the loop start method of signaling while PBX trunks use ground start. Whether a system uses ground start or loop start depends on the local phone company central office requirements.

Guard Tour (Watch Tour) - the programmed patrol guard schedule in and around the facility.

GUI - Graphical user interface.

H Back to Index

HAD - Hole accumulated diode. A type of CCD sensor with a layer designed to accumulate holes (in the electronic sense), thus reducing noise level.

Half Duplex - a multiplex system that can transmit in both directions, but not at the same time.

Handshake - a process in which predetermined character arrangements are exchanged by the receiving and transmitting equipment to establish synchronization.

Hardware Address - the unique physical address determined at the physical and data link layers. For example, each Ethernet card has a unique hardware address that is stored within the card.

Hardwired - devices that are connected with wire.

Harness - a bundle of wires with a connector for interconnecting field wiring to alarm modules.

HDD - Hard disk drive. A magnetic medium for storing digital information on most computers and electronic equipment that process digital data.

HDTV - High definition digital television. The upcoming standard of broadcast television with extremely high resolution and aspect ratio of 16:9. It is an advancement from the analog high definition, already used experimentally in Japan and Europe. The picture resolution is nearly 2000 x 1000 pixels, and uses the MPEG-2 standard.

Heat Detector - a device that detects the presence of highly heated air due to a fire. A fixed temperature heat detector is used to detect the fast buildup of heat due to the flame or flash of a fire. A rate of rise heat detector is used to detect the slow buildup of heat due to a smoldering fire.

Headend - The electronic equipment located at the start of a cable television system, usually including antennas, earth stations, preamplifiers, frequency converters, demodulators, modulators and related equipment.

Helical scan - A method of recording video information on a tape, most commonly used in home and professional VCRs.

Herringbone - Patterning caused by driving a color-modulated composite video signal (PAL or NTSC) into a monochrome monitor.

Hertz - An unit that measures the number of certain oscillations per second.

Holdup Alarm - an alarm initiated by a mechanical panic button or software panic on a keypad in response to a robbery or assault. Also referred to as panic alarms. On-site horns and bells should not be programmed to sound when a holdup alarm initiates.

Home - a condition of the system where perimeter devices only are placed into an armed state allowing the user to move freely about the inside.

Home/Sleep/Away - a system option that provides users with perimeter, interior, and bedroom areas that they can selectively arm from the keypad for maximum security. Selecting Away arms all areas of the system. Selecting Home arms only the perimeter protection of the system. Sleep arms the perimeter and interior areas, but leave devices near bedrooms and other nighttime areas off.

Homerun - a wiring method that connects individual sensors directly to the control panel using a single wire.

Hop - a unit of distance that measures the passage of a datagram through a router. The distance between networks is often measured by the number of hops.

Hop count - the number of routers that a datagram travels through on the way to its destination. You can adjust hop counts to provide routing flexibility.

Horizontal drive (also Horizontal sync) - This signal is derived by dividing sub-carrier by 227.5 and then doing some pulse shaping. The signal is used by monitors and cameras to determine the start of each horizontal line.

Horizontal resolution - Chrominance and luminance resolution (detail) expressed horizontally across a picture tube. This is usually expressed as a number of black to white transitions or lines that can be differentiated. Limited by the bandwidth of the video signal or equipment.

Horn, Motor Driven - an electrically operated horn in which the action of a motor-driven actuator against a metal diaphragm produces a signal.