cr systems

AC: A term used to describe Electrical Power. All household electrical power is AC (alternating current). Any device, which plugs into an electrical outlet in your home, operates on AC power. Security systems and other electronic devices plug into AC power and then convert it to DC power. See also: DC

Abort code: Your abort code is a word or number that you use to identify yourself to the central station in the case of a false alarm. If you accidentally set off your alarm, the central station dispatcher will ask you for your abort code. If you don't have one, or if you provide an incorrect one, the authorities will be dispatched. You will also need an abort code to make changes to your account.

Access point: A transceiver that allows wireless devices to connect to a wired local-area network, or LAN.

Active crossover: An electronic component that divides the audio signal from a source component into frequency bands (low and high, for example) before each band is separately amplified.

Active scan lines: Scan lines in a video frame that carry picture information rather than being used for other data (such as closed captioning) or for synchronization.

Ambience: The acoustical character of a listening or performing space, determined mainly by the timing, level, frequency balance, and directions of the sound reflections in it. Some digital signal processors can synthesize ambience by generating artificial reflections.

Ampere (A, amp): The primary unit of electrical current, which is the rate of flow of electrical charges.

Amplifier: A separate component, or a section built into an integrated component, that strengthens the electrical signal (increases its amplitude). A power amplifier, which is designed to drive speakers, must be connected to a preamplifier (or “control amplifier”) to switch and process the sound.

Amplitude modulation (AM): A technique in which the level (amplitude) of a high-frequency carrier signal is varied according to the level of a much lower-frequency signal so that the envelope of the carrier follows the waveform of the modulating signal, as when audio or video is impressed onto a radio-frequency (RF) carrier.

Analog: A type of component or recording medium that operates with continuously varying waveforms directly analogous to the signals they represent.

Analog-to-digital (A/D) converter (or ADC): An electronic circuit that converts an analog electrical signal into a sequence of binary numbers.

Anamorphic: A means of recording a widescreen image using special lenses or processing such that the image is distorted in the medium but restored to proper proportions during playback.

Arm/disarm: Describes the state of the security system. Describes action of turning on or off (activate or deactivate) your security system. There are typically several ways to arm a security system, “Stay”, “Away”, “Instant”, etc.

Aspect ratio: The ratio of width to height of a screen or image; expressed in whole numbers (4:3, 16:9). Describes the shape of a TV screen, regardless of the dimensions of the actual screen. (For example, a “widescreen” TV is 16:9 while a traditional TV has a 4:3 aspect ratio)

AATSC (Advanced Television Systems Committee): The industry/government body that issued the U.S. digital TV standard.

Attenuate: To reduce or lower a signal’s strength.

Audio/video (A/V): Any system or component that involves both audio and video elements, like a receiver or a preamplifier that switches video signals and processes multichannel audio signals (including surround sound decoding) for a home theater system.

Aux (auxiliary): An input on a receiver, integrated amplifier, or preamplifier that can be used to connect line-level source components; also, any general-purpose A/V input.

Away: Describes state of arming. The "AWAY" feature is a way of arming your complete alarm system, the exit delay will count down for 30 seconds to give you time to leave through the entry / exit zone before the system arms. All interior and exterior zones will be activated when using the "AWAY" feature.

Backlighting: A technique of illuminating the buttons and keys on a remote control so they can be identified even in a dark room.

Backup battery: The battery located in the Security Panel in the closet. The battery will keep your system functional for approximately 8 hours in the event of a power failure.

Balance: A control that changes the relative volume level in two or more channels.

Bass: The lowest part of the audio spectrum, from 20 Hz to 150 or 200 Hz; see treble and midrange.

Bass-reflex: A type of speaker enclosure in which the sound emitted from the back of the woofer’s diaphragm is used to augment low-frequency output by being fed through a port or a passive radiator; same as a “vented” enclosure.

Bit: The basic unit of information in digital audio or video, corresponding to on or off, 1 or 0; a contraction of “binary digit.”

Bit rate: The rate of transmission of digital data of any type, measured in bits per second (see data rate).

Bitstream: A signal that contains digital data in its undecoded state; often referring to the SPDIF digital audio output from a DVD.

Black-level control: On a TV, a control that adjusts the amount of light put out by the display when it receives the video signal for black (often called the “brightness” control). On a DVD player, a control that adjusts the video output voltage that’s generated when it reproduces data representing black.

Blocking: The perceptible breakup of a digital video image into an array of (usually) square blocks; can arise from inferior encoding or from a low data rate (high degree of compression).

BNC connector: A bayonet-type coaxial connector used on some A/V gear.

Bridge: A device that connects two local-area network (LAN) segments, whether they are similar or dissimilar types, such as Ethernet and HomePNA.

Bridged: A stereo or multichannel amplifier design that allows the hookup of pairs of output channels to drive one speaker with considerably boosted power.

Brightness: see black-level control.

Broadband: A high-speed Internet connection, such as DSL or cable modem, that’s fast enough to support downloading high-data-rate signals, such as streaming video.

Buffer: A temporary storage area for data, especially data read from a disc or downloaded from the Internet, so that playback can continue uninterrupted if the data flow is intermittent.

Burn: The process of recording with a laser on optical media in computer drives and standalone CD or DVD recorders. Nothing actually burns, but chemical reactions caused by the heat of the tightly focused laser beam produce spot-like changes in the disc’s reflectivity that can be “read” like pits in a pressed disc.

Bypass: A zone that is bypassed will not be activated when system is armed. This allows you to bypass the master bedroom window for ventilation. All openings on a zone are bypassed together.

Byte: A cluster or group of eight bits that are transmitted, processed, or interpreted together.

CableCARD: A removable PC Card supplied by a cable-TV service provider that enables reception of encrypted premium channels without a separate set top decoding box when it’s inserted in a digital cable ready HDTV.

Cable modem: A broadband Internet hookup where the modem connects through a cable TV line rather than a phone line.

Carrier: A high-frequency sine wave whose alterations in amplitude, frequency, or phase are used to convey (carry) the information in a much lower-frequency signal or band of signals.

Category 3 (Cat-3): Unshielded twisted pair (UTP) data grade cable (usually 24 AWG). CAT 3 cables are characterized to 16 MHz and support applications up to 10 Mbps. Typically used for voice telephone and 10Base-T Ethernet systems.

Category 5 (Cat-5): Unshielded twisted pair (UTP) Network cabling consisting of four twisted pairs of copper wire terminated by eight-conductor RJ-45 connectors; supports data rates up to 100 megabits per second.

Category 6 (Cat-6): Unshielded twisted pair (UTP) Like Cat-5, but supports data rates up to 1 gigabit per second (Gigabit Ethernet).

CD (compact disc): A polycarbonate disc 12 centimeters (approximately 4-3⁄4 inches) in diameter that can store more than 80 minutes of stereo sound in 16-bit linear PCM digital format. A laser pickup reads reflections from the microscopic “pits” and “lands” on its internal metallized information layer.

CD-R (compact disc–recordable): A format that permits data to be written onto a special type of blank CD but not erased from it.

CD-RW (compact disc–rewritable): A format that permits data to be written onto and erased from a special type of CD.

Center channel: A third front channel used to complement the front left and right stereo channels in a multichannel audio/video or surround sound system; its primary purpose is to stabilize the center of the reproduced soundstage for off-center listeners.

Central station monitoring: Security systems send their signals over a standard telephone line to a central monitoring station—the facility that acts as the link between your home and the police, fire department, and emergency response authorities. A central station is manned 24 hours a day, 7 days a week by highly skilled operators trained to respond to emergencies. The station operator alerts the proper authorities and dispatches help.

Channel: In audio, a distinct path for a signal; stereo and binaural signals have two channels; multichannel systems such as Dolby Digital, DTS, and Dolby Surround (Pro Logic) use additional channels for a center speaker in front and surround speakers at the sides or rear. In Dolby Digital and DTS, an LFE channel is devoted to loud low-frequency sound effects. In broadcasting, a channel is a specified frequency band assigned to carry a station’s signal.

Chrominance (C): A video signal carrying only the point-to-point color, both hue and saturation, of a video image and not its brightness; see luminance.

Class A: An amplifier operating design in which the output devices conduct current at all times.

Client: A component that receives information (such as digital music, movies, or photos) through a wired or wireless network; see media server.

Clipping: Overload distortion that occurs when an electronic device cannot accommodate the maximum level requirements of the input signal, shearing off (“clipping”) the waveform peaks.

Closed captioning: A system that transmits caption or subtitle text and symbol data during the non-image portion of a video signal. It requires special decoder circuitry for display, hence the “closed.”

Coaxial: A type of cable construction in which an inner conducting wire is surrounded by a shielding cylindrical outer conductor; commonly used in video and digital audio connections. Connectors maintaining this construction may also be referred to as coaxial. Also refers to a speaker configuration in which two drivers are mounted one behind the other so that their centers are in line.

Color control: A TV adjustment that changes the amount of chrominance applied to the image.

Color temperature: The specific shade of white produced by a TV in response to a pure-white (luminance only) input signal, measured in kelvins (K). Low color temperatures produce a “white” that’s tinted reddish-orange compared with the bluish “white” at high color temperatures.

Component: A separate piece of audio or video equipment, with its own chassis and power supply, that performs one specific function or set of related functions.

Component video: A method of transmitting video signals that continuously keeps the various color components separate from each other. Consumer component-video connections carry luminance and two color-difference signals; see YCrCb and YPrPb.

Component video cord: A trio of RCA connectors that carry video in a high-quality analog format, consisting of a black-and-white signal (Y) and two color difference signals (blue – Y and red – Y)

Composite video: A single video signal that combines three video sub-signals (luminance, chrominance, and sync). Until the development of S-video and component-video outputs, all video connections in consumer products were composite video.

Contacts, door and window: These are the devices that indicate the current status of a door or windows position, open or closed. Doors and most sliding windows use flush mount magnetic switches that may or may not be visible when the door/window is open. Single and double hung windows and some sliding windows use surface mount switches that are visible on the windowsill.

Contrast: In general, the range between the brightest and darkest parts of an image; on a TV, a control that adjusts the overall gain of the video signal on its way to the display; see contrast ratio.

Contrast ratio: A measure of the maximum and minimum light levels a TV can produce when fed the signals for maximum white and black, respectively.

Convergence: Adjustments in a CRT-based projection TV that align the primary-color images produced by the three internal CRTs. In a direct-view color TV, convergence refers to the alignment of the beams generated by the three electron guns.

Crossover (crossover network): A circuit or component comprising low-pass, high-pass, or bandpass filters that separate lower-frequency signals from higher-frequency ones. A crossover is used in a speaker that has more than one driver. In a two-way speaker, the crossover sends the low frequencies to the woofer and the high frequencies to the tweeter. See active crossover and passive crossover.

CRT (cathode-ray tube): A vacuum tube in which electrons emitted by a hot cathode are focused into beams and scanned across a phosphor-coated surface to produce a picture.

Current: The rate of flow of electrical charges in a circuit, measured in amperes.

Damping: The application of mechanical impedance, such as from a rubber or silicone material, to the suspension of a speaker diaphragm to reduce the amplitude of a resonance.

Data rate: The rate at which digital information is transmitted or received; in audio and video, the rate is typically measured in kilobits per second (kbps) or megabits per second (Mbps), but it can also be measured in bytes per second. Despite referring to digital data, “kilo” and “mega” here retain their normal metric meanings of 1,000 and 1,000,000, respectively.

DB-25: One of the family of computer-style D-sub connectors with 25-pin plugs and jacks; sometimes used for transferring multichannel analog audio.

DC: A term used to describe Electrical Power. Batteries store DC power (Direct Current). Items such as Wireless Devices, Automobiles, or any battery-operated device operate on DC power. See also: AC

Decibel (dB): The most commonly used measurement unit in audio, a decibel is a logarithmic unit expressing the ratio of two powers, currents, voltages, or sound-pressure levels (SPLs). An increase of 10 dB represents a tenfold increase in power, and an increase of 20 dB represents a tenfold increase in voltage. Doubling the power in watts delivered to a speaker raises its output SPL by about 3 dB.

Deinterlacing: The process of converting a field-based image (for example, the video on a DVD) to a frame-based image (as would be delivered from a DVD player’s progressive-scan output).

Delay, entry/exit: A delay of the zone to allow a timed exit after the alarm is armed and a timed entrance when returning. Typical exit delay time is 30 seconds and entrance time of 45 seconds. If alarm is not disarmed before time elapses, siren is activated and Central Station Monitoring is notified (if Monitoring enabled).

Demarc: Demarcation Point, see NID

DHCP (Dynamic Host Configuration Protocol): A computer protocol that enables a networked device to automatically extract its IP address from a server that’s also on the network.

Digital: A digit is a number, and digital devices use numbers in some way. A digital tuner, for example, may use numbers only on its front-panel display, or it may use digital frequency-synthesis tuning circuits. Digits can also be used to represent analog signals, as in digital audio or video. A CD carries a pattern representing a series of 16-bit binary numbers (16-digit strings of 1s and 0s); a CD player converts these numbers into a continuously changing voltage that represents the recorded music.

Digital audio server: A component containing a harddisk drive and a CD recorder that can rip CDs to the hard drive, encode audio signals from other sources, and send and receive files to/from computers or other digital audio devices on a home network.

Digital cable-ready: A video component, typically a digital TV, featuring a slot for a CableCARD that enables decoding of premium channels.

Digital Light Processing (DLP): A technology developed by Texas Instruments that utilizes a Digital Micromirror Device to project video signals.

Digital output: A coaxial or fiber-optic output found on some CD and DVD players and digital recorders that is used to send digital audio signals to a component with a digital input; see SPDIF.

Digital signal processing/processor (DSP): A general term for the mathematical manipulation of signals that are in digital form. DSP can be used for a wide variety of tasks, including ambience enhancement, equalization, filtering, time-alignment, and noise reduction of audio and video signals. A digital signal processor can be either a separate component or a part of one.

Digital subscriber line: see DSL.

Digital TV (DTV): Broadcasts of digital television signals in the U.S. following the standards issued by the ATSC, which specify the 18 formats to be used. The most common high-definition (HDTV) formats are variants of 1080i (1,080 interlaced scan lines) and 720p (720 progressive scan lines), while the standard-definition (SDTV) formats use 480 progressive-scan lines (480p) or 480 interlaced scan lines (480i). Though the SDTV formats can have both widescreen (16:9) and conventional (4:3) aspect ratios, HDTV is widescreen only.

D-ILA (Direct-drive Image Light Amplifier): A reflective liquid-crystal technology used for high-resolution displays, also known as LCoS (liquid crystal on silicon).

Direct-view TV: Usually refers to a CRT set whose single picture tube is intended for viewing head on, not projecting onto a screen.

Distortion: Broadly speaking, any unwanted alteration of a signal; usually it refers to an unnatural-sounding nonlinear distortion, which adds to the output signal components that are mathematically related to the input signal.

Dolby Digital (DD): The Dolby Labs format for digital surround sound providing up to 5.1 channels; used in DVDs, the digital TV system, and some laserdiscs; formerly called AC-3 (for Audio Code 3).

Dolby Digital EX: A system of encoding a quasi-6.1-channel signal within the 5.1-channel framework of a standard Dolby Digital data stream. The sixth channel is encoded by matrix techniques on the left and right surround channels of the Dolby Digital signal. The first licensed decoding system was THX Surround EX, but some digital surround receivers and processors use a generic matrix-decoding system for 6.1 playback.

Dolby Pro Logic (DPL): An enhancement to Dolby Surround decoding that extracts a center channel and improves channel separation by means of logic-steering circuitry. Most DPL recoders today operate in the digital domain.

Dolby Pro Logic II and IIx (DPL II, DPL IIx): DPL II is a digital enhancement of DPL that can manipulate a Dolby Surround-encoded or plain two-channel stereo signal to simulate 5.1-channel playback, with separate modes optimized for Movies and Music. DPL IIx adds 6.1/7.1-channel playback for systems with one or two back surround speakers.

Dolby Surround: The consumer name for the Dolby Stereo system used for movie soundtracks. Dolby Surround encoding matrixes four channels — left, center, right, and surround — into two stereo-compatible channels (L T/RT) that can be carried on any two-channel sound medium. Basic Dolby Surround decoding extracts the single surround channel to feed a pair of speakers at the sides or back of the room; such decoders have now largely been superseded by Dolby Pro Logic decoders as well as by Dolby Digital systems.

Door speaker: Intercom speaker used at any Entry. Front door, gate, etc. Door Speakers have a doorbell button and a speaker.

Dot pitch: The horizontal spacing between repetitions of the red, green, and blue phosphor pattern in a color CRT. It’s measured in millimeters.

Download: To transfer data such as music, video, text, or still images from an online source to a local storage medium, whether a computer hard-disk drive or a removable flash-memory device; also, transferring audio or other data from a computer to a portable device.

Driver: An individual woofer, midrange, or tweeter, or other transducer within a speaker.

DSL (digital subscriber line): A method of highspeed data transfer over ordinary copper telephone lines (see broadband). A generic name for evolving digital services provided by local telephone companies to their local subscribers. Such services go by different names and acronyms - ADSL (Asymmetric Digital Subscriber Line), HDSL (High Bit Rate Digital Subscriber line) and SDSL (Single Pair Symmetrical Services). Such services propose to give the subscriber up to eight million bits per second one way, downstream to the customer and somewhat fewer bits per second upstream to the phone company.

DTCP (Digital Transmission Content Protection): A copy-protection scheme developed by Intel to prevent programming transmitted via a digital connection like FireWire (a.k.a. IEEE 1394 or i.Link) from being copied without permission of the copyright holder.

DTS: A multichannel codec developed by Digital Theater Systems and used to carry a 5.1-channel soundtrack on DVDs, CDs, and laserdiscs.

DTS Extended Surround (DTS-ES): A development of DTS that adds 6.1-channel capability. There are two types of DTS-ES, Matrix and Discrete. DTS-ES Matrix can be decoded by any decoder that also handles DTS-ES Discrete or Dolby Digital EX.

DTVLink: An IEEE 1394 (a.k.a. FireWire, i.Link) interface found on a digital TV, HDTV tuner, or digital video recorder that meets certain Consumer Electronics Association specifications for interoperability.

Duress code: A Duress Code is a Silent Panic transmitted to our Central Monitoring Station. It could be used in a Hostage situation, allowing you to turn off your alarm while calling for the Police. Requires Central Station Monitoring.

DVI (Digital Visual Interface): A high-speed digital interface for visual data (both video and still images), typically used in connecting a computer with a display device but also on a growing number of HDTV’s, HDTV monitors, and HDTV tuners as well as on some DVD players.

DVD: A high-capacity optical-disc format that enables vast amounts of audio, video, or computer data to be encoded on a laser-read disc the size of a CD.

DVD-Audio: A music-oriented DVD format that can carry up to six channels of audio at up to 24 bits resolution, with or without video or interactive content; typical sampling rates are 48, 96, and 192 kHz. Most also carry Dolby Digital or stereo soundtracks for playback (though not at high resolution) on DVD-Video machines that lack DVD-Audio decoders.

DVD changer: A DVD player that holds three or more discs at a time.

DVD-RAM: A rewritable (erasable) recordable DVD format officially supported by the DVD Forum. DVD-RAM discs are compatible only with DVD players designated to play them.

DVD+R: A write-once (non-erasable) recordable DVD format.

DVD+RW: A rewritable (erasable) recordable DVD format. DVD+RW discs are said to be playable on most present-day DVD players.

DVD-R: A write-once (non-erasable) recordable DVD format.

DVD-RW: A rewritable (erasable) recordable DVD format. DVD-RW can be recorded in two modes, Video (essentially the same as standard DVD-Video) and VR, which allows for extensive editing. Video mode DVD-RW discs are said to be playable on most present-day DVD players, but VR mode recordings are less widely compatible.

DVD-Video: A DVD format used almost exclusively for movies and other image-intensive program material; it employs MPEG-2 video encoding and Dolby Digital or DTS and PCM stereo audio encoding. Most movie DVDs offer up to 5.1 channels of surround sound, and today most come in widescreen format.

D-VHS: A development of the Super VHS system that records video and audio as digital data on a special VHS-size videocassette. D-VHS machines will also play standard analog S-VHS and VHS tapes. Some prerecorded HDTV movies are available in this format.

EDTV: see enhanced-definition TV.

EDTV monitor: A TV set that can display a 480p-format digital TV signal from an outboard tuner/decoder.

802.11: see IEEE 802.11.

Electronic crossover: see active crossover.

Electronic program guide (EPG): An onscreen program guide/menu system used to select the program to be viewed; can also be used to set the recording timer in a VCR or hard-disk recorder. Schedule information is downloaded at night from the program service provider via a home network and broadband connection, a built-in modem connected to a telephone line, or a cable or satellite feed, or it’s decoded from a TV channel’s VBI.

Enclosure: The box or other construction that makes up the outer shell of a speaker. Its principal purposes are to hold the drivers in alignment and to prevent the sound from the back of a woofer from reaching the front in an uncontrolled way that would result in cancellation of low frequencies.

Enhanced-definition TV (EDTV): A TV that’s capable of displaying the 480p (progressive-scan) format at up to 60 fps — with either a 16:9 or 4:3 aspect ratio — rather than being limited to SDTV’s 480i (interlaced-scan), 30-fps format.

Equalizer: A component, or part of a component, that divides the audio signal into frequency bands with separately adjustable output levels.

Ethernet: Trademark for a wired-network protocol covered by the IEEE (Institute of Electrical and Electronics Engineers) 802.3 international standard. Standard, Fast, and Gigabit Ethernet have maximum data rates of 10, 100, and 1,000 Mbps, respectively.

F-connector: The final piece of hardware on a cable designed for CATV or DBS or other signal distribution applications. It is cylindrical with a center pin sticking out, that plugs into the set-top box, cable ready TV, satellite receiver, or VCR.

Fiber-optic: A transmission medium in which signals are carried through a special plastic- or glass-fiber cable in the form of light; the primary benefit is immunity to electrical noise. See Toslink, ST.

Filter: A circuit that boosts, attenuates, or removes selected frequencies from audio signals.

Fire detection: There are several devices to detect Fire. Smoke Detectors are used in living areas to detect smoke and excessive heat. Heat detectors are used in non-living areas such as garages and attics to detect excessive heat. Heat detectors are not considered life saving devices as you could be overcome with smoke before they are triggered. Heat detectors do not false alarm due to dust, dirt, fog, smoke, etc.

Firewall: A system for preventing network access by unauthorized users.

FireWire: see IEEE 1394.

5.1-channel: The conventional designation for a medium or system that carries six channels of sound information: front left/center/right, surround left/right, and a restricted-bandwidth (hence the “.1”) LFE channel.

Fixed-pixel display: Any display technology that utilizes separately activated pixels of constant size. Of the major TV display technologies, only CRT is not fixed-pixel.

4:3, 4x3: see aspect ratio.

Frame: A complete, individual picture on a motion picture film or contained in a video signal.

Frame rate: The rate at which frames are displayed. In typical modern movies the frame rate is 24 per second; in color NTSC video it’s 30 per second.

Frequency: Rate of vibration or oscillation, measured in cycles per second, or hertz (Hz). The audio spectrum is generally taken to be 20 to 20,000 Hz (20 Hz to 20 kHz), which encompasses all the frequencies humans can hear. In radio, frequency refers to the carrier signal of the station, such as 88.1 MHz for an FM station or 770 kHz for an AM station.

Frequency modulation (FM): A technique in which the frequency of a high-frequency carrier is varied according to the level of a much lower-frequency signal. Commonly used to impress an audio signal onto a radio- frequency (RF) carrier.

Frequency response: The range of frequencies (or bandwidth), expressed in hertz (Hz), that a component can handle, within specified limits of amplitude error, expressed in decibels (dB).

Front projector: A type of video display in which the projector elements are housed in a separate unit, not connected to the screen and mounted in front of it, much like a movie projector; front projectors are often mounted on the ceiling.

Gain: How much the amplitude of incoming signals is changed by a circuit or antenna, usually in decibels (dB). Gain can be positive, for amplification; negative, for attenuation; or 0 dB for no change, or “unity gain.”

Giga (G): The metric prefix for billion. In reference to digital data, giga usually stands for 1,073,741,824 (230).

Gigabyte (GB): One billion bytes (plus 73,741,824, to be exact), a measure of digital information storage capacity; commonly specifies the data-storage capacity of such media as DVDs and hard-disk drives.

Graphic equalizer: An equalizer with control bands that are fixed in frequency but variable in level; the slider controls for the various bands provide a rough graphic representation of the selected frequency-response curve.

Graphical user interface (GUI): Any “point-and-click” control system for an electronic component that uses menus and icons displayed on a screen instead of (or in addition to) physical pushbuttons and other controls.

Grayscale: On a video display, the intermediate steps of gray between absolute black (0 IRE) and white (100 IRE). In the analog NTSC video system used in the U.S., black level is specified as 7.5 IRE.

Ground: In an electrical circuit, the reference for 0 volts, above and below which other (AC) signals may vary. An electrical term, which quite literally refers to an electrical connection to “earth” or “earth ground”. All electrical outlets have a “ground” connection; phone and TV services are “grounded” upon entering your home for safety.

Hand held remote: Many of our security systems can be equipped with a Handheld Panic Button or a Multiple Button Device to allow control of your Security System as well as a Panic Button.

Hard-disk drive: A digital data storage/retrieval device utilizing a rigid, rapidly rotating disk coated with a magnetic recording surface. Thanks to the rapid rotation rate, the read/write head(s) float on a cushion of air very near the disk’s surface, allowing almost instantaneous cueing to any desired location without touching the surface.

Hard-disk recorder (HDR): A device using the immense data capacity of a hard-disk drive to store audio or A/V material in digital form. Video-oriented HDRs — often called “'digital video recorders” (DVRs) and sometimes “personal video recorders” (PVRs) — usually have versatile options for unattended recording and playback that can let you skip commercials or watch a program from the beginning while it’s still being recorded.

HD-DVD: A high-capacity disc format approved by the DVD Forum for carrying high-definition video programs. The sandwiched disc structure resembles that of ordinary DVDs, but blue lasers instead of red are used to obtain high data density.

HDMI (High Definition Multimedia Interface): An enhanced version of DVI that adds stereo and multichannel digital audio as well as signals for integrated remote control and infrared (IR) repeater functions on a single cable with a 19-pin connector that’s significantly smaller than a DVI connector. HDMI incorporates the HDCP copy-prevention scheme.

HDTV monitor: A TV set that can display high-definition images when connected to an outboard HDTV tuner.

HDTV set: An HDTV display that has a built-in high-definition tuner.

HDTV tuner: An outboard, usually set-top, digital TV tuner/decoder that can receive high-definition programs broadcast over the air as well as from a satellite receiver or cable service and then decode the signals for display on an HDTV monitor.

Hertz (Hz): The standard unit of frequency, representing cycles per second, or changes away from a basic state and back again. In audio, the basic state is defined as either ordinary air pressure (without sound) or its electrical equivalent: a constant-level (DC) signal, often 0 volts, or ground. For a sound in the audible range, the higher the frequency in hertz, the higher the pitch. In video, frequency usually relates to horizontal luminance resolution; the higher the frequency, the finer the detail and the higher the resolution. A kilohertz (kHz) is a thousand hertz, a megahertz (MHz) a million hertz, and a gigahertz (GHz) a billion hertz.

Hi-fi: High fidelity, used to refer to an audio system that can reproduce recorded sound with substantial fidelity to the original. VHS Hi-Fi is an audio recording system for VCRs.

High-definition TV (HDTV): A specific subset of the digital TV standard that features increased horizontal and vertical resolution, choice of interlaced or progressive scan, and widescreen images.

High-pass filter: A circuit, as in a speaker’s crossover network, that progressively attenuates signals below its cutoff frequency, passing those above unaltered; see filter and low-pass filter.

Home network: A system in which at least one computer is linked with A/V and other devices via wires or wireless means so that digital audio or video files don’t have to reside on the device that plays them.

Home theater system: A collection of audio and video components designed and configured to reproduce something like the picture and sound quality of a movie shown in a good cinema. A home theater is generally expected to include a TV screen of reasonable size and a surround sound audio system.

Hue: A color’s position in the visible spectrum from red to blue, or its gradation of tint; the professional name for a video monitor’s tint control.

IEEE 802.11: A specification developed by the IEEE (Institute of Electrical and Electronics Engineers) for wireless networking. 802.11a operates in the 5-GHz band with a maximum data rate of 54 Mbps. 802.11b operates in the 2.4-GHz band with a top data rate of 11 Mbps. 802.11g operates in the 2.4-GHz band with a maximum data rate of 54 Mbps and is compatible with “b” devices. 802.11e is a forthcoming specification that includes the QoS (Quality of Service) feature to provide improved streaming of multimedia content.

IEEE 1394: The IEEE standard for high-speed, high-capacity digital connections of audio and video components, computers, and peripherals; also known as FireWire and i.Link.

i.Link: see IEEE 1394.

Imaging: The ability of an audio system to reproduce sounds in a spatially realistic manner.

Impedance: In electronics, the total resistance of a component or circuit to the flow of alternating current (AC), expressed in ohms. In addition to pure resistance, it may include reactive (capacitive or inductive) elements that cause its value to vary with frequency; see reactance.

Inside wiring: Any wiring located inside your premises or building. Inside wiring starts at the telephone or cable company's Demarcation Point (NID) and extends to the individual extensions. Typically, the homeowner owns the inside wiring.

Instant: Describes a security reaction of zones. Zones can be Instant or Delay. Instant means they react instantly to being opened, triggering an immediate alarm.

Instant arming: Describes a security state of arming. Activating the "INSTANT" feature arms only the perimeter zones of your home. Zones, in most cases, can be assigned as either perimeter or interior zones. Once the "INSTANT" feature has been activated, one can stay inside the home and move around without the risk of setting off the alarm system. Only the perimeter doors and windows will be armed, so if someone breaks into the house through a perimeter door or window, the alarm will be set off. All perimeter zones are INSTANT, including entry / exit zones.

Integrated amplifier: A component that combines the functions of a preamplifier and power amplifier.

Interlaced: A video component or signal that assigns alternating scan lines in a video frame to one of two fields, which are then displayed separately. Interlacing is used to reduce picture flicker without increasing the frame rate.

Jack: A female connector that serves as a receptacle for a male connector, or plug; see RCA connector.

JPEG: A storage format for digital images, devised by the Joint Photographic Experts Group, that uses a scalable “lossy” data-compression scheme to reduce file size.

Kilo (k): The metric prefix for thousand. In reference to digital data, kilo usually stands for 1,024 (210).

Kilobits per second (kbps): A statement of bit rate or data-transfer speed, usually encountered in reference to downloaded music files in MP3 and other compressed-audio formats, where 128 kbps is often cited as the “standard” for acceptable sound quality, though the quality at that rate can actually vary considerably depending on which codec was used. See codec and MP3, AAC, RealAudio, and Windows Media Audio.

Kilobyte (kB): 1,024 bytes; a measure of digital information-storage capacity.

Laser: A device that generates a coherent, monochromatic beam of light. These two characteristics allow a laser beam to be focused down to very small areas, a trait essential to its use in the CD, DVD, MD, and other optical or magneto-optical data-storage systems.

LCD (liquid-crystal display): Color LCD panels are used in some flat-screen TVs and computer monitors as well as in some video-projection systems. Monochrome LCD readouts are used on the faceplates of some A/V components and remote controls.

LED (light-emitting diode): A semiconductor device used as an indicator light on many components.

Letterboxing: The scaling of a widescreen image to fit within a squarish 4:3 aspect ratio screen by shrinking the image’s vertical dimension so that the width fits exactly and filling the resulting spaces above and below the image with black bars. Critics of the technique think that the screen area is being “wasted” by the letterboxing bars; see pan-and-scan.

LFE (low-frequency effects) channel: The “0.1”-channel of a 5.1-channel surround sound system, containing only very low frequencies; in movie soundtracks it is used primarily for loud sound effects.

Light activation: HAI Omni series of automation systems can turn on lights when the security system is triggered. This can be utilized as a burglar deterrent by drawing attention to your home.

Line-level: Signal voltages in the range delivered from the outputs of most audio source components (such as CD players) and preamplifiers; also known as low-level or preamp-level. See speaker-level.

Lines of resolution: The units that describe the ability of a TV, camera, video recorder, or other device to convey fine picture detail; higher values are usually better. Normally refers to horizontal resolution but can also describe vertical resolution; see scan lines, with which lines of resolution are often confused.

LNB (low-noise block downconverter): A device mounted at the focal point of a satellite dish that amplifies the microwave signals collected by the dish and converts them to a lower frequency that’s sent to a satellite receiver over standard coaxial cable.

Local-area network (LAN): A system for connecting computers and other digital devices in close proximity so they can share files, multimedia content, and resources.

Logic: In a surround sound system, “logic-steering” is used to improve separation between multiple channels derived from matrix-encoded two-channel signals.

Loudness compensation: A form of equalization that progressively emphasizes low frequencies (and sometimes high frequencies) as volume is reduced. Loudness-compensation circuits are designed to offset the ear’s loss of low-frequency sensitivity as the sound level decreases.

Low-pass filter: A circuit, as in a speaker’s crossover network, that progressively attenuates signals above its cutoff frequency, passing those below unaltered; see filter and high-pass filter.

Lumen: A unit for the rate of flow of visible light.

Luminance (Y): The portion of a video signal in which point-to-point brightness — not the color (chrominance) — of an image is encoded. Black-and-white TVs display only luminance signals.

Lux: A unit of illumination, equal to one lumen per square meter.

Macro: A series of operations programmed to be executed with just one button push on a remote control.

Macrovision: A set of alterations of a standard video signal designed to prevent copying it or, failing that, to severely degrade the quality of any copies made. DVD players usually apply two types of Macrovision processing to their outputs, “pseudo pulse” and “color striping,” via circuitry enabled by instructions on the copy-protected disc.

Master station: Intercom unit typically placed in family/kitchen area. Includes radio tuner, master radio volume control, master intercom volume control, room speaker and room talk/listen controls.

Matrix: A type of circuit commonly used in surround sound encoders and decoders to squeeze three or more channels of information into two or to extract multiple channels from an encoded two-channel signal; also used to describe similar circuits that can synthesize an ambience channel from a non-encoded stereo recording. The term “matrix” derives from the mathematics involved. See Dolby Digital Surround EX, DTS-ES, Dolby Pro Logic, Dolby Surround

Media adapter: see media receiver.

Media receiver: A component attached to a TV or stereo system to access digital music, photos, or video through a wired or wireless network; also called a media adapter.

Media server: A computer or computer like component that stores music, photos, or video and makes them available to a TV or stereo system either directly or through a wired or wireless network. Also see client, media receiver, and server.

Medical emergency pendant: Necklace pendant can be ordered to alert paramedics of medical emergency. Requires Central Station Monitoring.

Mega (M): The metric prefix for million. In reference to digital data, mega usually stands for 1,048,576 (220).

Megabyte (MB): One million bytes; a measure of digital information-storage capacity.

Megachanger: A CD or DVD changer that holds 50 or more discs at a time in a jukebox-like mechanism.

Microprocessor: An integrated circuit containing a complete central processing unit (CPU) of a computer. A microcomputer is a complete computer (comprising a CPU, memory, and input/output circuitry) on a single IC chip.

Midbass: The segment of the audio frequency spectrum covering sounds produced in the upper-bass and lower-midrange regions.

Midrange: The segment of the audio frequency spectrum between the bass and treble, which includes most of the fundamental tones of the human voice and of most musical instruments; it runs from approximately 150 or 200 Hz to around 3 kHz.

Midrange driver: A speaker driver designed to reproduce frequencies from 200 Hz or so up to 2 to 3 kHz.

Mode: A recording-quality setting on a DVD or harddisk recorder; also types of surround sound processing, whether it involves plain decoding of a format like Dolby Digital or ambience/sound-field generation. See ambience, recording mode, surround sound.

Modem: A peripheral device used to convert digital signals ("1s" and "0s") into analog signals (tones) and vice versa, necessary for communication using standard telephone lines.

Monitor: In audio, a speaker used in recording or other professional applications; in video, the term can refer to any display device, including TVs, but is often used specifically to denote a display device without tuning functions.

Mono (monaural or monophonic): A recording or signal containing one channel of audio. In a component, it indicates that only one channel is handled, as in a mono power amplifier.

Motion detector: Also referred to as PIR. Motion detectors sense rapid heat changes in its field of view. Motion sensors cannot detect heat changes through glass. Motion detectors may detect extremely bright light, as light waves generate heat.

MP3: The common term for the audio codec officially known as MPEG-1 Layer 3. Originally used for sound data in computer-related applications and now popular for music files ripped from CDs or downloaded from the Internet and played on a computer or portable digital device; also see mp3PRO and MPEG-2.

MPEG (Moving Picture Experts Group): A committee of engineers and scientists formed to issue standards for reduced-bit-rate digital audio and video.

MPEG-2: The standard reduced-bit-rate audio/video encoding scheme for digital TV, DVDs, and certain digital satellite transmissions.

MPEG-4: A data-encoding standard incorporating advancements to MPEG-2 and AAC in addition to facilities for the synthesis and manipulation of audio and video “objects” (shapes, textures, sounds, and so on). Also see H.264.

Muddy: A subjective term describing reproduced sound, usually in the bass, that isn’t as clear as it should be.

Multichannel: An audio system or component using more amplifier/speaker channels than a stereo pair; see 5.1-channel, 6.1-channel, home theater system, Dolby Digital, Dolby Surround, Dolby Pro Logic, DTS, SDDS.

Multichannel analog input: A connection consisting of six or more RCA jacks that allows the hookup of a source component supplying a decoded surround sound output, such as a DVD-Audio or Super Audio CD player or some DVD-Video players.

Multiplex (MPX): Two or more channels transmitted on a single carrier so that the receiver can independently recover them. Usually, as in TV and stereo FM, this is achieved by means of sub carriers, signals on the main carrier that are themselves modulated by other signals.

Native resolution: The picture resolution, usually expressed in horizontal by vertical pixels (such as 1,024 x 768) that a TV or other display device is inherently capable of without making use of line doubling, line interpolation, or other forms of rescaling. In a fixed pixel display like a plasma, LCD, or DLP TV, the native resolution is the same as the actual pixel layout.

NID: Network Interface Device. Phone Company connector box, where your house phone wiring is attached. Phone Company is responsible for all wiring up to and including the NID. Also referred to as a “Demarcation point or demarc”.

Noise: Any unwanted signals that are not strongly correlated with the desired signal and that usually arise from a random process. Hiss and hum are typical examples of audible noise. In video programs, noise appears as “snow” onscreen or graininess in the image.

NTSC (National Television System Committee): The industry/government body that issued the U.S. analog color TV standard approved by the FCC (Federal Communications Commission) in 1953; any video signal or component that operates according to that standard.

Off-air: Reception of a TV signal that has been broadcast through the air by a TV station.

Ohm (Ù): The basic unit of electrical resistance; also see impedance.

Optical (fiber-optic) input/output: A special type of jack that accepts fiber-optic connectors; see ST and Toslink.

Output-current capability: A rating, in amperes, of the maximum current an amplifier can supply.

Output level: A measure of the strength of the output signal of a component.

Paging feature: Ademco security panels can be programmed to page you when disarmed, a good feature with if kids live in the house.

PAL (phase-alternating line): The analog TV standard for Western Europe except France (see SECAM) and much of the rest of the world except Japan and North America (see NTSC).

Pan-and-scan: A technique for making a widescreen movie fill a 4:3 aspect ratio screen by showing only selected parts of the original image, re-cropped scene by scene to focus in on what seems most significant to the action. Critics of this technique think the re-cropping compromises the director’s intent. See letterboxing.

Passive crossover: A network, typically built into a speaker, comprising some combination of capacitors, inductors (coils), and resistors that divides the audio signal into frequency bands (low, high, and possibly midrange) after it is amplified; see active crossover.

Peripheral: A device or system hooked up to (or sometimes inside of) a computer, like a monitor, printer, hard drive, CD or DVD drive, or speakers.

Phase: The timing relationship among a set of audio waveforms or among the components that make up the spectrum of a single waveform. Also a control that changes polarity.

Phase-locked loop (PLL): A circuit used in radio tuners to lock the received frequency to a synthesized reference frequency; see frequency synthesis.

Phone module: A Phone Module allows you to control your security system over a touchtone phone from within the home or by calling in to your system remotely. All of our systems have Phone Modules available. The Ademco Vista Series of panels offers an optional Phone Module; speak to your C&R Representative for details. The HAI Omni Home Automation includes Phone Activation.

Phono input: The circuit in a preamplifier, integrated amplifier, or receiver that amplifies the low-level signals produced by a phono cartridge, raising them to the same level as signals from other audio source components (called line-level), and also applies the necessary RIAA equalization.

Phosphor: A chemical lining the inside face of a CRT that glows when struck by electrons fired by an electron gun. Color CRTs have a repeating pattern of red, green, and blue phosphors named after the colors they emit when irradiated. See dot pitch.

Picture-in-picture (PIP): A TV function that allows the simultaneous display of two different programs on the same screen, usually with a small image of the subsidiary program(s) superimposed over that of the main program.

PIR: see Motion detector

Pixel (picture element): The smallest subunit of an image that’s treated separately in a digital video system or a non-CRT video display. Pixel counts are often quoted in specs for image sensors, LCD viewfinders, plasma and LCD flat TVs, and LCD and DLP projection TVs; see front projector and rear-projection TV.

Plasma: A type of video display that employs an enormous array of tiny cells of ionized gas (plasma), which is used to activate each cell’s colored phosphor.

Polarity: An electrical convention that describes one side of a circuit connection as positive and the other as negative. Reversing, or inverting, the polarity of an audio connection is equivalent to a wideband phase shift of 180°; see reverse polarity.

Port: An opening (also called a vent) in the cabinet of a bass-reflex speaker that enables the sound wave from the back of a woofer to reinforce the sound wave from the front; equivalent to a passive radiator.

Power: The rate of transfer or absorption of energy per unit time in a system. Electrical power is usually measured in watts, as in the output specifications for a power amplifier.

Power amplifier: A component, or part of a component, that strengthens the audio signal from a preamplifier so that it can drive speakers.

Powered speaker: A speaker, usually a subwoofer that has an amplifier built in.

Power supply: A subsection of a component that takes AC line voltage and converts it to one or more DC voltages to operate the rest of the circuitry. In audio, power-supply design can have an enormous influence on noise levels and the maximum output power an amplifier can produce.

Preamplifier: A component, or part of a component, that switches and processes signals from a variety of source components.

Preset: A memory circuit that is programmed by the user. For example, tuner presets store the frequencies of radio or TV stations so they can be recalled instantly.

Programming: The process of entering instructions for a component to carry out at a later time. For instance, many CD players can be programmed to play selected tracks in any order; see macro.

Progressive scan: A video component or signal that processes or displays each scan line of a video frame in sequence; the opposite of interlaced scan.

Quartz: A form of crystalline silicon dioxide that can be used to construct very stable radio-frequency (RF) oscillators and clocks.

Radio Data System (RDS): A system for transmitting text information along with the audio in a radio broadcast for display on an RDS-equipped tuner or receiver.

Radio-frequency (RF): The high-frequency electromagnetic signals used to broadcast radio and TV programs, or any very high-frequency signal, whether intended for broadcast or not.

Random access: The ability to go directly to the beginning of a numbered or labeled song, track, chapter, disc, or program without scanning the intervening material.

RCA connector/plug/jack: The most common kind of audio connector, using a small, single-pin plug and a coaxial shield.

Rear-projection TV (RPTV): A TV set that beams the output of video transducers (CRTs, DLPs, LCDs, and the like) in the rear of its cabinet onto an angled mirror, which in turn reflects it onto a large screen (from 40 to 80 inches diagonal) at the front of the cabinet.

Receiver: An audio component that receives radio broadcasts, switches and processes audio signals, and amplifies the selected signal to drive speakers; also see A/V receiver. A television receiver is a monitor that contains a tuner for TV signals.

Red, green, and blue (RGB): The three primary additive colors of most video systems (such as NTSC and DTV); also, the three color signals used by computer monitors. An RGB video connection provides each color as a discrete signal (also see RGB+H/V).

Regional coding: A “feature” of the DVD system that gives program producers the ability to restrict the geographical areas in which a DVD can be played. The U.S. and Canada are Region 1; Europe is Region 2.

Residential gateway: A device that combines the functions of a cable or DSL modem and a router.

Resistance: Electronic “friction” that turns the flow of electrical charges into heat; resistance is impedance that is the same for all frequencies.

Resolution: A measure of the ability of a video system to convey fine image details. Most resolution specifications or measurements are for horizontal luminance resolution, but there can be vertical luminance and color resolution figures as well.

Resonance: The tendency of a mechanical or electrical system to vibrate at a certain frequency when excited by an external force, and to keep vibrating even after the exciting force is removed. Resonances are undesirable in audio equipment and listening rooms because they can produce colorations.

Reverberation: A dense pattern of diffuse and multiple reflections that results when sound is created in an enclosed space. The more reflective the walls and surfaces of the listening space, the louder and longer lasting the reverb; the perceived effect of reverberation depends on the size of the room and how long it persists. Reverberation influences both the clarity and intelligibility of the sound (the more, the muddier) and the feeling of spaciousness or ambience (the less reverb, the more closed-in the sound will seem).

Reverse polarity: An electrical condition in which the “positive” and “negative” wires running to one speaker in a stereo pair are reversed relative to the other; this causes the sound waves emanating from the speakers to be out of phase with one another, which weakens bass output by cancellation and impairs stereo imaging.

RF: Radio Frequency. Analog electrical signals sent on cable or over the air. Conventional (broadcast) television and radio, as well as cable TV, deliver RF signals to your television/radio.

RF interference (RFI): When a radio or TV broadcast or other radio-frequency signal interferes with the operation of a component.

RGB+H/V: see red, green, and blue.

Rip: To extract the digital audio data from a CD; also applied to the process of converting such data to a compressed audio format, typically MP3.

RJ-11: A standard modular telephone jack.

RJ-45: The standard Ethernet connector found on home-network components.

Rollover: Automatic call forwarding if first phone number is busy. Typically used in office environment.

Room station: Intercom remote speaker used in bedrooms, bonus rooms, garages, patio, etc. have speaker, volume control and talk controls.

Router: A device for dividing an Internet connection among multiple computers or networks.

RS-232: A standard for serial communications ports on computers and some A/V components.

SAP (secondary audio program): A separate mono channel broadcast along with the two stereo channels in the U.S. system for stereo analog TV. The SAP channel can be used for an alternative-language soundtrack or descriptions for the sight-impaired.

Saturation: In video, saturation is the intensity of a color, specifically defined as its “distance” from white (for example, a lightly saturated pink vs. a deeply saturated red); also, the professional name for a video monitor’s color control. In audio, saturation occurs when an analog tape becomes fully magnetized and an increase in signal input level does not produce a corresponding increase in recorded level; saturation can also occur in the magnetic structure of the tape heads.

Scan line: One of the thin horizontal strips that together make up a video field or frame. The basic subunit of an analog video image; see pixel.

SDTV monitor: A TV set that can display a 480i-format standard-definition digital TV signal when connected to an outboard tuner/decoder.

Serial Copy Management System (SCMS): Incorporated in all consumer digital audio recorders to limit digital-to-digital copying of copyrighted music to a single generation. Any number of first-generation digital copies can be made from a digital original, but the resulting copies cannot themselves be copied via a direct digital link.

Server: Any device that makes stored data available to other devices, often through a wired or wireless network; see client, media server.

Set-top box: Any of several types of decoder, such as for cable TV, digital TV, or Internet functions, designed for hookup to a TV set.

7.1-channel: A 6.1-channel system where a recorded back surround channel is reproduced by two speakers, usually with individual amplification. Strictly speaking, however, unless additional processing is applied to send a different signal to each speaker, it’s still one channel in surround sound terms.

Sharpness control: A TV control that affects the middle to high frequencies of the luminance signal, which convey the subjective impression of sharpness.

Short: A “short” is a connection made inadvertently. For instance, if you had an extension cord with frayed wire, you could experience a “short”, or, an accidental connection.

Signal: An electromagnetic wave, current, or voltage whose variations carry audio or video information.

Signal processor: A component that manipulates line-level audio signals; equalizers and surround sound processors are the most common varieties.

6.1-channel: Any system that has provisions for a back surround channel, reproduced by one or two speakers centered behind the listening position, in addition to the conventional left and right surround channels of a 5.1-channel system; see 7.1-channel.

16:9, 16x9: see aspect ratio.

Solid-state: Electronic circuits whose active elements are transistors and integrated circuits, and specifically not vacuum tubes.

Sony Dynamic Digital Sound (SDDS): A multichannel audio reproduction system for movie theaters utilizing ATRAC encoding and featuring as many as five front channels along with two surround channels and an LFE channel.

Soundstage: The virtual space created by an audio system; either the imaging of a stereo pair of speakers at the front of a room or the three-dimensional sound field created by all of the speakers in a multichannel home theater system. (Of course, the original soundstage is the real space where a movie soundtrack is recorded.)

Speaker (or loudspeaker): A component that accepts audio signals from a receiver or amplifier and converts them into sound waves for listening at some distance (unlike headphones); see driver.

Speaker-level: Audio signals that have been sufficiently amplified to drive a speaker; see line-level.

Specification (spec): A manufacturer’s numerical rating of a component’s performance in terms of a discrete, measurable characteristic such as frequency response or distortion.

Spectrum: The frequency and amplitude distribution of the various pure-tone components that make up a complex waveform; commonly shown in a graph with amplitude on the vertical axis and frequency on the horizontal.

Splitter: A passive device (one with no active electronic components) which distributes a television signal carried on a cable in two or more paths and sends it to a number of receivers simultaneously.

Standard-definition TV (SDTV): A subset of the digital TV (DTV) standard covering digital signals that will yield picture quality at least as good as that of analog NTSC television; see high-definition TV (HDTV ) and enhanced-definition TV (EDTV).

Stay: Describes security state of arming. Activating the "STAY" feature arms only the perimeter zones of your home. Zones, in most cases, can be assigned as either perimeter or interior zones. Once the "STAY" feature has been activated, one can stay inside the home and move around without the risk of setting off the alarm system. Only the perimeter doors and windows will be armed, so if someone breaks into the house through a perimeter door or window, the alarm will be set off. Entry / exit zones have delay.

ST (AT&T ST) connection: A fiber-optic digital audio connector that uses glass fibers rather than plastic; see Toslink.

Stereo: The use of two or more audio channels to provide spatial realism or directional effects; nowadays “stereo” usually refers only to two-channel programs, equipment, or systems. See imaging, binaural, multichannel.

Streaming media: Digital audio or video data downloaded from the Internet or from a computer on a home network for simultaneous decoding and playback.

Subwoofer: A speaker designed to reproduce only low-bass frequencies. A powered subwoofer contains an amplifier and an electronic crossover.

Super Audio CD (SACD): A high-density audio disc that uses Direct Stream Digital (DSD) audio encoding. “Hybrid” SACD pressings are playback-compatible with both SACD and standard CD players.

Super VHS (S-VHS): A development of the VHS videocassette system that originally required special tape to obtain its extended luminance resolution.

Surround: Channels or speakers in a multichannel audio system whose purpose is to create a sense of sonic envelopment or all-around directionality. Also a compliant suspension at the outer edge of a speaker driver’s diaphragm.

Surround sound: A reproduced sound field that is three-dimensional instead of a soundstage heard primarily in front of the listener; an audio system or part of a home theater system that creates such a sound field. See 5.1-channel, 6.1-channel, Dolby Digital, Dolby Surround, Dolby Surround EX, Dolby Pro Logic, DTS, DTS-ES, home theater, and THX.

S-video: A connector that separately carries the luminance and chrominance information for a single video signal; a set of video signals divided into luminance and chrominance components.

THX: A certification for audio components of a home theater system that adhere to standards and specifications developed by Lucasfilm THX and can reproduce soundtracks with very high fidelity to what is obtained in a movie sound studio. There are two grades of certification, THX Ultra2 (for price-no-object setups) and THX Select (for modest room sizes and budgets).

THX Surround EX: Circuitry for decoding Dolby Digital Surround EX signals approved by THX Ltd.; may include THX enhancements of plain DD Surround EX.

Tint control: The consumer video-monitor control that adjusts the general coloration of an image; see hue.

Tone controls: A kind of rudimentary equalizer included in most receivers, and in some preamplifiers and integrated amplifiers as well, that allows changing the relative balance among preset frequency bands, usually bass and treble but sometimes also midrange.

Toslink: The most common fiber-optic connector for digital audio; uses plastic fibers; see ST.

Tracking: The ability of a CD or DVD player to follow the pattern recorded on a disc in the presence of physical or optical disturbances.

Transducer: Any device that transforms energy of one type into energy of another type. Speakers, microphones, image sensors, CRTs, and plasma displays are all transducers.

Transformer: A passive electrical device that raises or lowers AC voltages (as in a power supply ), or changes input or output impedances; used in some amplifiers to match their output impedance to that of the speakers.

Transistor: The basic solid-state amplifying element used in most audio components; see solid-state, fieldeffect transistor (FET), and MOSFET.

Treble: The upper part of the audio spectrum, from 2 or 3 kHz up to 20 kHz; see bass and midrange.

Tuner: A component, or part of a component, that receives radio or TV signals from an antenna or cable connection, allows the user to select a station, and demodulates the audio or audio/video signal from the broadcast radio-frequency (RF) signal.

Tweeter: A speaker driver designed to reproduce treble frequencies.

two-way, three-way, and so on: Refers to the number of frequency bands a speaker’s output is divided into. A two-way speaker has a woofer and a tweeter; a three-way speaker adds a midrange driver. Four-way power towers add a built-in subwoofer.

UHF Ultra High Frequency; the part of the radio spectrum from 470 MHz to 806 MHz, including TV channels 14 through 83.

Universal remote control: A remote that can operate multiple devices, not simply a single component, and usually from more than one brand or manufacturer. Universal remotes are either preprogrammed with control codes for a multitude of specific products from most popular brands, or they can be “taught” the infrared codes used by the dedicated remotes you already have, thus replacing them.

Universal Serial Bus (USB): A general-purpose standard connection for transferring digital audio, video, or control signals between A/V components, computers, and computer peripherals. USB 2.0 is a newer version of the interface capable of much higher data rates.

V-chip: An integrated circuit built into a TV set that allows parents to automatically restrict the viewing of objectionable material. It works in conjunction with program-content codes transmitted with the TV signal; see Extended Data Service.

VGA: A PC graphics standard equivalent to RGB+H/ V and found as an output option on some HDTV tuners and as an input on some HDTV monitors and projectors. Instead of five RCA jacks, it uses a 15-pin D-Sub connector.

VHF Very High Frequency: The part of the radio spectrum from 54 to 88 MHz and 174 to 216 MHz, which includes TV channels 2 through 13.

Video CD: A forerunner to the DVD system designed to produce “VHS-quality” video using a standard-size CD and MPEG-1 video encoding; also see MPEG-2 .

Virtual surround sound: A system that can simulate the effect of multichannel surround sound using only two speakers or headphones. Many of these systems work well if you sit exactly in the “sweet spot,” but the illusion diminishes or vanishes if you move.

Voice coil: In a dynamic speaker or microphone, a hollow cylinder wound with wire that is immersed in the field of a permanent magnet and attached to a diaphragm. In a speaker, current through the wire from the amplifier creates an alternating magnetic field in the coil that causes it and the diaphragm to move back and forth according to changes in the input signal. In a microphone, sound moving the diaphragm also moves the coil, generating a signal voltage in it that is fed to a recorder or directly to a sound system for amplification.

Voltage: The measure, in volts, of the strength of an electrical field; it can be thought of as pressure pushing electrical charges through a circuit, forming a current.

ordings.

Waterflow switch: A waterflow switch may have been installed if you have automatic fire sprinklers in your home. Your fire sprinkler installer is certified to install the switch. Waterflow switches are typically mounted in the garage in a red enclosure. Waterflow switches can be tied into your security system to enable automatic dispatch of the fire department if fire sprinklers are triggered. Requires Central Station Monitoring.

Watt (W): The primary unit of electrical power.

Watts per channel: A specification of the output power an amplifier or receiver can deliver to each speaker connected to it.

WAV (.wav) file: A Microsoft Windows file format for storage of audio data, typically, but not necessarily, in linear-PCM form; often applied to other file formats that also store PCM audio data.

White balance: In a camcorder, the control or system that compensates for the different quality of color produced by different sources of scene illumination (sunlight, incandescent bulbs, and so on) as seen by its image sensor.

White noise: A type of random noise characterized by equal energy per hertz (in contrast to pink noise). White noise is naturally generated by analog electronics, and the ear hears it as a treble-dominated hissing.

Wideband component video: An output on a DVD player or other device that can generate or pass progressive-scan or high-definition video signals to a TV set or monitor able to display them.

Widescreen: A piece of program material or a component that contains or operates with images of wider than “normal” aspect ratio (which is 4:3). High-definition TV ’s widescreen aspect ratio is 16:9. Display of wider images on a 4:3 screen requires letterboxing or pan-and-scan techniques.

Wi-Fi (Wireless Fidelity): A certification logo for Ethernet devices that comply with certain wireless standards (see IEEE 802.11).

Windows Media Audio (WMA): An audio codec, developed by Microsoft, used for downloaded music files and streaming media applications.

Windows Media Video (WMV): A video codec, developed by Microsoft, for streaming multimedia and downloaded video files. A high-definition version, WMV HD, is now available.

Woofer: A speaker driver designed to reproduce bass or bass/midrange frequencies.

XLR: A three-conductor balanced-line connector; also called a Cannon connector.

YCrCb: Digital component-video signals as recorded by professional digital video recorders and encoded by an MPEG-2 encoder for recording on a DVD; often confused with YPr Pb.

YPrPb: Analog component-video signals as obtained at the outputs of a DVD-Video player or a digital TV set-top box.

Zone: A listening/viewing area in a multiroom audio or A/V system.

Zone, instant: Security zone that activates an immediate alarm when a contact is opened while the alarm is armed. Typically used for doors and windows not requiring an entry/exit delay.

Zone, interior: An interior zone is a zone that is armed only in an “Away” mode. If the system were armed in a “Stay” mode, the interior zone would not be activated to allow you to move about inside the home. Typically used for motion detectors.

Zone, entry/exit: Security zone that activates an Entry/Exit Delay. Typically used for the Front Door and Garage Entry Door to allow a timed entrance.

Zone, fire: Security zone with a fire device on it. Fire zones are active 24 hours a day whether alarm is armed or not. Fire zones used in conjunction with Central Station monitoring provide 24-hour fire protection with automatic Fire Department response. See your C&R Systems Representative for details.

ABBREVIATIONS:

480i: 480 scan lines, interlaced

480p: 480 scan lines, progressive

720p: 720 scan lines, progressive

1080i: 1,080 scan lines, interlaced

A, amp: ampere

AAC: Advanced Audio Coding

A/D: analog-to-digital

A/V: audio/video

AC: alternating current

ADC: analog-to-digital converter

AE: auto exposure

AES: Audio Engineering Society

AFC: automatic frequency control

AGC: automatic gain control

AM: amplitude modulation

amp: amplifier or ampere

ANSI: American National Standards Institute

ATRAC: Adaptive Transform Acoustic Coding

ATSC: Advanced Television Systems Committee

aux: auxiliary

A/V: audio/video

AWG: American Wire Gauge

BD: Blu-Ray Disc

B-frame: bidirectional frame

BJT: bipolar junction transistor

B – Y: blue minus luminance

BPF: bandpass filter

bps: bits per second

CATV: community-access (cable) TV

CCD: charge-coupled device

CCTV: closed-circuit TV

CD-R: recordable CD (unerasable)

CD-ROM: computer data CD

CD-RW: rewritable CD

CEA: Consumer Electronics Association

CEDIA: Custom Electronic Design and Installation Association

CG: character generator or computer graphics

CIE: Commission International de l’Éclairage (International Commission on Illumination)

CRT: cathode-ray tube

D/A: digital-to-analog

DAB: digital audio broadcasting

DAC: digital-to-analog converter

DAT: digital audio tape

dB: decibel

dBA: decibel, A-weighted

dBf: decibel re 1 femtowatt

dBFS: decibel re digital full-scale

DBS: direct broadcast satellite

dBW: decibel re 1 watt

DC: direct current

DCDi: Directional Correlation Deinterlacing