Kramer Worldwide

The science and study of sound as related to hearing and music.

"Background noise" as distinct from the acoustics of sound.

An electronic device designed to increase electrical signals including: current, voltage, or a combination of the two, AKA "power"

The absolute value of a current waveform or voltage at maximum capacity.

An electronic device used to manipulate and/or alter audio signals.

A representation of sound, generally using electrical voltage for analog signals, or binary numbers for digital signals.

The conversion of acoustical energy into electrical energy and vice versa.

Audio Video Bridging (AVB) is a series of technical standards developed by the Institute of Electrical and Electronics Engineers (IEEE) Time-Sensitive Networking Task Group to allow time-synchronized, low-latency audio streaming services through IEEE 802 networks.

A bidirectional microphone responds to both the front and rear, excluding side sounds; also called "figure of eight."

Also known as a "pressure zone microphone (PZM)", a boundary microphone is mounted on a flat plate; this works as a reflective surface to direct sound into the mic capsule.

A heart-shaped pattern used for handheld and lavalier microphones to reduce unwanted ambient sound. Wider than a unidirectional pattern, it provides greater resistence to feedback.

Increased air pressure and density which is the result of sound wave passage, or the region where this occurs.

A signal processing device which reduces the dynamic range of the signal transiting through it; controls the overall amplitude of a signal by reducing that part of the signal which exceeds an adjustable level (threshold) set by the user.

Also called a "capacitor microphone" or "electrostatic microphone,"  a condenser microphone transduces sound into electricity and operates on external voltage via phantom power.

The most commonly-used component in a loudspeaker system and found in all ranges of drivers.

The portion along a length of a recorded tape on which sync control information is placed; used to control the recording and playback of the signal.

The Audinate trademark for the company's proprietary digital audio networking technology; a combination of network proticals, hardware and software which delivers multi-channel, uncompressed,  low-latency digital audio over a standard Ethernet network using Layer 3 IP packets.

A measure of sound pressure level measured in dynes per centimeter squared. Its reference,  0 dBSPL, equals 0.0002 dynes/cm2. dBSPL is used as a measure of acoustical sound pressure levels  and is a 20log function.

The preferred method to represent the ratio of various audio levels; abbreviated as "dB".

A signal processing device/circuit which can delay one or more output signals by a controllable amount. It is used to correct loudspeaker drivers mounted with their points of apparent sound origin not physically aligned.

A sound field which lacks direction or random sound.

Sounds which travel directly to the person who is listening, reaching its location first and without using "reflections."

A sound system with multiple loudspeakers separated by distance, which typically operates in a lower sound pressure level than a high pressure system. The loudspeakers are most often suspended over the listeners' heads.

Used in all ranges of drivers.

In audio,  an individual speaker unit.

A microphone designed to attach a wire coil (known as the "voice coil") to a small diaphragm; sound pressure causes the coil to move in a magnetic field, which creates an electrical voltage that is proportional to the sound pressure itself.

Created by sound waves which are reflected (bounced) off surfaces between the source and the listener. The sound waves arrive at the listener’s ear closely on the heels of the direct sound wave.

Also known as "acoustic echo cancellation" (AEC), this technique uses digital sound processing (DSP) to filter out any undesired signals caused by echoes from the lead source of the audio.

Also known as the "EQ", this electronic filter adjusts/augments acoustic and electronic systems.

An audio processor which increases the dynamic range of a passing signal; it comes in two types: a downward expander and part of a compander.

1) Unwanted noise caused by the loop of an audio system’s output back to its input. 2) In a control system,  data supplied to give an indication of status,  i.e.,  on or off.

A small microphone designed to be worn either around the neck or clipped to apparel.

An audio signal compressor with a fixed ratio of 10:1 that prevents the signal from exceeding the threshold level.

A device used to monitor the output of an audio signal from a system in a local vicinity.

An electromagnetic transducer, which converts the electrical energy output of a power amplifier into acoustic energy.

In audio electromechanics, microphone sensitivity is the rating of the microphone's output.

Loudspeakers that reproduce midrange frequencies,  typically 300 Hz.

A device for blending multiple audio sources by adjusting their levels independently in real-time.

Also known as "monaural" and commonly abbreviated as "mono," the monophonic can record, reproduce or transit sound when a source(s) are connected to a single channel.

Called the "nearfield listening position," nearfield offers the best stereo output when the listeners and speakers heads are arranged in an equilateral triangle.

Describes the shape of the pickup area for "perfect sphere" omnidirectional microphones, which have equal sensitivity to sound from nearly all directions; a non-directional microphone.

Designed to provide power supply voltage to specific microphones using the matching two lines of the balanced audio path.

Sometimes called "Euroblocks," these are molded,  plastic, captive screw connectors. They can only be terminated by "compression termination."

An audio connector used as a speaker connector and unbalanced/balanced audio connector for musical instruments. Common types are 1/4 inch (full size) and 1/8 inch ("mini").

A common name for an RCA connector.

Random noise source which has equal energy per octave. Pink noise is created by passing white noise through a filter with a 3 dB/octave roll-off rate..

A sound system that has a central location for the loudspeaker(s),  mounted high above,  intended to cover a large area; typical of a performance venue or a large house of worship.

Also called a "pickup pattern;" describes the shape of the area where a microphone will be most sensitive to sound. There are seven microphone polar patterns: cardioid; figure-of-eight; hypercarioid; omnidirectional; shotgun; subcarioid; and supercardioid.

Also known as a "phono jack" or "pin jack," it is the standard connector commonly used in consumer line-level and studio sound equipment; the RCA connector also interconnects composite video signals.

Sound waves that bounce off of multiple surfaces before reaching the listener,  but arrive at the listener’s ears quite a bit later than early reflected sound.

A long,  cylindrical,  highly sensitive,  unidirectional microphone used to pick up sound from a great distance; note that it must be pointed directly at the source for clearest recordings.

Multi-channel sound that appears to have a three-dimensional presence. This may involve dozens of speakers or special phasing. A commercial example would be Dolby Atmos.

A specialized connector used to hook up speakers without causing a short circuit; allows connection of the speaker while working  or hot.

Any recording or transmission system which uses multiple loudspeakers to reproduce sound as captured by multiple microphones.

Actually a large woofer loudspeaker, subwoofers reproduce the tail-end of audio, that is, the last octave, from 20 Hz to 80-100 Hz.

The exaggerated heart-like shape of the area where a highly directional microphone is most sensitive to sound.

Also called a "boundary microphone" or "pressure zone microphone" (PZM), it is mounted on a flat plate which serves as a reflective surface directing sound into the microphone capsule; utilitizes the PZM principle.

Popular term describing sound systems which use more than mono and stereo loudspeakers to provide a 2- or 3-D auditory experience.

Tip-Ring-Sleeve; a stereo connector, used as a three-wire phone jack.

Tip-Sleeve; a mono connector, used as a two-wire phone plug.

A type of high-frequency loudspeaker.

A narrow pickup pattern used with microphones to reduce high-level ambient background noise.

Much like white light, white noise has all audible frequencies in equal amounts.

A low-frequency loudspeaker.

A simple, peer-to-peer computer network connection between two devices. "Ad hoc" is derived from the Latin for "as needed." 

Advanced Encryption Standard. An standard supported by the National Institute of Standards & Technology (NIST) which uses a block length of 128 bits and key lengths of 128, 192 or 256 bits.

A protocol used exclusively by Apple to allow wireless streaming of video and audio content from iPhones, iPads, and Macbooks to a connected television and/or audio system.

The Google operating system for smartphones, tablets, some smart televisions, and Chromebooks. This is an application-driven OS.

The smallest unit of digital information. Shortened form of binary digit,  symbolized by 1s and 0s. The abbreviation for bit is a lower-case "b".

Blue River NT is chip technology developed by Aptovision (new Semtech). The core is SDVoE™ technology.

An 8-bit word is called a byte. The abbreviation for byte is an upper-case "B".

A digital media player interface, usually in the form of a USB dongle, which allows anyone to cast Internet video to a connected television that supports Google Cast (VP9).

Stands for Central Processing Unit. The portion of a computer system that reads and executes commands.

A term used to describe an AV-IT network that is firewalled at all inputs and outputs to isolate it from an adjacent LAN, thus guarding against attempted hacks and intrusions.

Dynamic Host Control Protocol. DHCP is used in network switches to assign IP addresses automatically to connected IP devices that are set to DHCP mode.

A process by which a secure connection can be made to exchange data. A special code is devised to disguise, hide, or make inaccessible bits of data, using sophisticated keys. Only a matching key at the receiving end will decrypt the encrypted data.

A network protocol that is defined by IEEE 802.3. That protocol refers to layer 1 (Physical layer) and Layer 2 (Data Link layer) of the OSI-7 model. That protocol is used in Local Area Network (LAN).

Forward error correction (FEC) is built-in to encoders and decoders to recover dropped packets. Always results in increased signal latency.

Hypertext Transfer Protocol Live Streaming. An HTTP-based media streaming communications protocol implemented by Apple Inc. as part of its QuickTime, Safari, OS X, and iOS software.

Hyper Text Markup Language. A markup language that is used to create documents on the World Wide Web incorporating text, graphics, sound, video, and hyperlinks.

Hypertext Transfer Protocol. An application-layer protocol for transmitting hypermedia documents, such as HTML. It was designed for communication between web browsers and web servers.

Internet Group Management Protocol, used for enabling multicasts of video and audio over a network connection. A network switch for AV signal management must support this protocol.

The Apple operating system for smartphones and tablets (iPhones and iPads). This is an application-driven OS specifically designed for mobile devices.

Internet of Things. A term used to describe the spectrum of devices that can connect to and be operated via an Internet connection, such as voice recognition systems, smart thermostats and lighting, doorbell cameras, smart appliances, and a host of AV hardware.

Jumbo Frame MTU is 5 times greater (9000 Bytes) then IEEE 802.3 Standard MTU value (1500 Bytes).

Local Area Network. A network that uses layer 1 and Layer 2 only from the OSI-7 model, i.e.: uses the Physical layer and Data link layer for packets traffic, without routing.

A protocol developed by the WiFi Alliance to allow direct wireless streaming of video content up to 1080p/60 and multi-channel audio from a mobile device to a connected television. Miracast uses the WiFi Direct standard to establish and maintain a streaming link. It can work with any operating system.

A process by which the entire screen of a connected mobile device is duplicated on a larger screen, such as a television or projected image. Can be used for video streaming at low frame rates.

Dynamic Adaptive Streaming over HTTP. A method of video streaming over HTTP ports that is not affected by firewalls and requires no special proxies or memory cache. Similar in operation to HLS.

System software that manages computer hardware and software resources and provides common services for computer programs.

The Open Systems Interconnection (OSI) model consists of 7 layers: Physical, Data Link, Network, Transport, Session, Presentation and Application.

Random Access Memory; the most common computer memory used by programs to perform necessary tasks while the computer is on; an integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible.

Read Only Memory; memory whose contents may be accessed and read but cannot be changed. Permanent memory that can only be entered once, normally by a manufacturer; may not be altered or removed.

Real Time Streaming Protocol. RTSP is a common control protocol for streaming media over the network.

Software-Defined Video Over Ethernet. An alliance that is based on the Semtech chipset for streaming over 10G networks.

Small Form-factor Pluggable is a compact, hot-pluggable optical fiber module transceiver used for both telecommunication and data communications applications.

Secure Reliable Transport is an open source video transport protocol and technology stack that optimizes streaming performance across unpredictable networks with secure streams and easy firewall traversal.

A network topology where all network devices are connected to a central network device that is usually a hub or a switch. The only type of network in use today.

Streaming is a technology that compresses the content and delivers it by packets over the actual media. All video streaming protocols are based on transport protocols. The most frequently used are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). The size of each data stream depends on various factors, including actual file size, bandwidth speed and network latency. One of the most common compression types of streaming is the known MPEG standard. Streaming can be delivered by Video On Demand application or Real-Time application.

Transmission Control Protocol / Internet Protocol. The most widely used Internet protocols.

Universal Datagram Protocol. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network.

A term used to describe a set of communication services and solutions bundled, sold and delivered together on one platform, such as voice, data, Internet, and video services.

Unshielded twisted pair cable, typically used for data transfer. It contains multiple 2-conductor pairs twisted at regular intervals,  employing no external shielding.

Wide Area Network; a data communications system that uses telecommunications circuits to link a variety of local area networks (LANs) to each other over large geographic distances.

A free, open project that provides browsers and mobile applications with real-time communications capabilities via simple application program interfaces. Supported by all major Web browsers.

A one-way flow of information dispersed to a large audience over the Internet. The audience does not usually contribute to the content of the webcast,  which might include an audio stream,  presentation slides,  video clips,  or live speakers.

A general term to describe various types of online collaborative services. These can include web seminars (Webinars), webcasts, and peer-to-peer web meetings.

An online interactive meeting or seminar. The audience is typically smaller than a webcast and contributes to the discussion via polling,  Q&A,  or other collaborative means.

Wireless Local Area Network; a wireless network that uses physical layer and data link layers only. It shares information by connections at microwave radio frequencies in the 2.4 and 5 GHz radio bands.

Distortion on a audio or video signal due to the compressions of the original source. Usually caused by insufficient sampling and/or excessive compression.

AOMedia Video 1 (AV1) is an open, royalty-free video coding format designed for video transmissions over the Internet. It is being developed by the Alliance for Open Media (AOMedia) and is intended to be 50% more efficient than H.264.

Bit Error Rate, or the number of packets with errors over a specific time interval. A low BER indicates the system is transmitting packets correctly.

Bi-directional frame. Found in a Group of Pictures in the MPEG standard. These frames predict temporal and spatial changes in video frames, looking forward and backward.

The number of bits that represent a sampled analog signal. The greater the bit depth, the more accurate the digital representation.

A coding tree unit (CTU) is the basic processing unit of the High Efficiency Video Coding (HEVC) video standard. CTUs can be as large as 64x64 pixels with HEVC coding.

A cyclic redundancy check is an error-detecting code commonly used in digital networks to detect accidental changes to raw data during transport. CRC is built-in to MPEG-based video encoders.

Display Stream Compression. A codec specifically designed for visually lossless and low latency compression of display signals by a maximum ratio of 3:1. DSC is the basis of Blue River NT compression technology.

A signal that has been sampled and compressed into another form to reduce its size or complexity, usually to conserve bandwidth.

Forward error correction, built-in to all MPEG-2, H.264 AVC, and H.265 HEVC streams to ensure all packets are successfully received. FEC is not used with JPEG compression.

Group of Pictures. The GOP is used in MPEG-2, H.264 AVC, and HEVC H.265 compression and is made up of I, P, and B frames. The GOP length determines bit rate and latency.

A version of MPEG compression, known as MPEG-4 Advanced Video Codec, that is widely used for video streaming compressed TS and MPTS files.

H.265 (High Efficiency Video Codec) is the successor standard to H.264, aka MPEG-4 AVC . The advantage of H.265 vs. H.264 is that H.265 requires roughly 50% less bandwidth than H.264.

Hexadecimal is a base/positional number system with a base of 16. It uses 16 unique alpha-numeric symbols with the numbers 0-9 to represent themselves, and the letters A-F to represent the values of 10-15. One hexadecimal digit is equivalent to four binary digits.

Intracoded frame, also known as a key frame as it contains all picture elements and is not compressed. A Group of Pictures starts and ends with I frames.

Joint Photographic Experts Group. A standard for sampling and light compression of still and video images with low latency.

A wavelet-based image coding system with a high level of scalability. Video content can be coded just once at any quality level and decoded at many other quality levels and resolutions.

The difference in time between when video/audio is captured and when it is seen and/or heard at the display.

A block of pixels used in MPEG-2 and H.264 AVC video compression. A basic macroblock can be 2x2 pixels (MPEG-2) and as large as 64x64 pixels (HEVC H.265 transform unit).

Moving Pictures Experts Group. Also a standard for sampling and heavy compression of video images with moderate latency. MPEG-2 is widely used for broadcast, cable, and satellite television.

MPEG-H Audio can carry audio channels, audio objects and ambisonics audio, plus metadata within a single audio bitstream. It is used for 3D spatial sound.

Predictive frame. Found in a Group of Pictures. These frames predict temporal and spatial changes in video frames, looking forward only.

How many samples of the analog signal are taken in a given time interval in creating the digital signal.

Tiny Codec, also known as JPEG XS "mezzanine" compression. A form of JPEG compression that works up to 6:1 levels and is gaining in popularity for streaming 4K/ Ultra HD video and 8K video.

A new lossless video compression and decompression system that has a targeted efficiency of 50% over the HEVC H.265 codec. Its maximum coding tree unit size is 128x128.

A royalty-free codec developed by Google that is similar in operation to HEVC H.265. It has a maximum block size of 64x64 units and is used exclusively to play out YouTube video content.

Any light in a viewing room produced by sources other than the display.

A screen that reflects light back to the viewer at a complementary angle.

The ratio of image width to image height. Can be expressed in whole units (i.e. 16x9) or as a mathematical ratio (1.77:1).

Additional numerical or text information provided as an overlay while wearing headgear or special glasses in a real environment. Heads-up displays are examples of AR.

An area outside the visible image that may contain synchronization and metadata. Applies to both video and display images.

The metric unit for measuring illuminance of a display. Candelas per square meter (cd/m2) are also referred to as "nits."

A visual artifact caused by insufficient bit depth sampling or representation of content, usually in areas with smooth gradations. The transition from one luminance value to the next is too great, resulting in an abrupt change in luminance value and creating what appears to be a contour line.

A proprietary technology for projectors that uses tiny, movable mirrors to create images. Developed by Texas Instruments and widely used for digital cinema.

A digital interface for computer video and audio that can also be copy-protected.

Digital Light Processing(c) by Texas Instruments. A projection system that has technology based on the Digital Micromirror Device (DMD). It uses thousands of microscopic mirrors on a chip focused through an optical system to display images on screen.

Digital Micromirror Device. The semiconductor chip used in DLP imaging.

A display device that emits its own light to create an image. OLEDs and LEDs are emissive displays.

Any display that uses a matrix of pixels, including LCD, DLP, LCoS, OLED, and LED technologies.

1 square foot of surface radiating 1 lumen of light.

High-bandwidth Digital Copy Protection, an encrypted data layer for display and USB interfaces to prevent copying of protected video content. The current version is 2.2, adopted in 2013. It employs AES-128 encryption and a 20 millisecond "locality" check to verify a secure connection is made. Version 2.3 will shorten the locality check to 7 milliseconds.

High Definition Multimedia Interface, a digital interface for video and audio that can also be copy-protected.

High dynamic range video. Video captured with more than 11 stops of light from full black to peak (specular) white, requiring at least 10 or more bits of color depth to display.

High frame rate. For video, frame rates exceed 50/60 Hz (typically 100 and 120 frames per second). High frame rates for cinema include 48 and 96 frames per second.

A technique whereby blue laser diodes and green-yellow color wheels are combined to produce white light for projectors.

Liquid-crystal display. The most common type of large screen display, using liquid crystals and polarizers to shutter light and filters to create color images. This is a transmissive display technology.

Liquid Crystal on Silicon. A reflective imaging technology for projectors using small liquid-crystal chips.

Light-emitting diode, also classified as inorganic light-emittig diodes to distinguish from OLEDs. These semiconductor devices produce intense colored light and are used for lamps, indicators, and high-brightness indoor and outdoor displays.

A screen surface characterized by silvered or aluminized embossing,  designed to reflect maximum light over wide horizontal and narrow vertical angles. Must be held very flat to avoid hot spots. Also referred to as a "gain screen."

The SI measurement for illuminance. A measure of the total quantity of visible light emitted by a source. 1 lumen equals 1 candlepower/12.56.

The SI measurement of luminance flux per unit area. One lux is equal to one lumen per square meter.

A video compression artifact that shows up as small, square-shaped tile patterns across an image. Also known as "tiling."

A screen that evenly disperses light  both horizontally and vertically,  creating a wide viewing cone and wide viewing angle free of "hot spots." Typically has a gain of 1.0.

The numbers of horizontal and vertical pixels that create the picture. The native resolution describes the actual resolution of the imaging device and not necessarily the resolution of the delivery signal. Often used to describe electronic displays.

Equal to 1 candela per square meter.

Organic light-emitting diode. An emissive display technlogy that can use white or colored emitters to produce images with high color saturation and wide viewing angles.

A device which produces an image on a screen by transmitting light through transparent acetate placed on the stage of the projector.

A chemical substance which glows when struck by an electron beam,  providing the image in a CRT. The higher the quality of the phosphor,  the brighter and more vivid the image. In a laser projector, a blue laser is projected onto a phosphor wheel to create yellow light, and the blue and yellow beams are then combined to create white light.

A pixel clock is a timing signal for video pixels. The speed of the pixel clock is determined by the video resolution and the refresh rate, and is often referred to as the bandwidth of the video signal.

A direct view display made up of an array of cells,  known as pixels,  which are composed of three subpixels,  corresponding to the colors red,  green,  and blue. Gas in the plasma state is used to react with phosphors in each subpixel to produce colored light (red,  green,  or blue) from a phosphor in each subpixel.

A prism beam splitter refracts white light into separate color components. In a projector, it works with filters to create red,  green,  and blue components.

Presents all pixels in an image in a progressive fashion, starting from the top of the video frame and proceeding through all the lines to the bottom of the screen.

A technique to create different levels of luminance by switching an imaging element or pixel on and off rapidly for different time intervals. Used by DLP and LED imaging systems.

A micro-crystalline compound that emits intense, pure colored light when stimulated by photons. Increasingly used in LCD televisions to show high dynamic range (HDR) content.

Light or sound energy that has been redirected by a surface.

Any display device that reflects light to create an image, such as Digital Light Processing or LCoS.

The bending or changing of the direction of a light ray when passing through a material,  such as water or glass. How much light refracts,  meaning how great the angle of refraction,  is called the refractive index.

The rate at which sequential frames of video are presented, expressed in Hertz (Hz).

1) The amount of detail in an image. 2) The number of picture elements (pixels) in a display.

A self-contained rear projection system.

A processor that re-scales the pixels in an image to match that of the display Scaling may be required when the image size does not fit the display device, adding or removing pixels as necessary. Artificial pixels may be interpolated between frames, lines and pixels and added to the original signal during the process.

The distance from the projection lens to the screen surface.

Any display device that uses light shuttering to pass or block light, creating grayscale and color images. An LCD TV or monitor is a transmissive display, as is a rear-projection screen.

The viewing angle determines how far off the axis (screen centerline) a viewer can still sit and still see a quality image.

The best viewing area for the audience. The term cone is used because there is width,  height,  and depth to the best viewing area, which emanates from the center of the screen.

An artifically-generated "reality" observed with special eyewear or in controlled environments on a large screen. The viewer can interact with virtual reality, simulating motion, direction, and depth cues, along with artifically-generated sounds and soundscapes. This is an immersive experience, separate from the real world.

Wide color gamut video. This is the ITU Recommendation BT.2020 color gamut, used for high dynamic range imaging. HDR and WCG go hand-in-hand.

The maximum angle a conductor can be bent to before excessive attenuation is encountered,  signal integrity is compromised,  or the conductor breaks.

A material (usually a metal or metal compound) that conducts an electric current because some electrons in the material are free to move.

The technology by which people separated by distance come together to share information. Conferencing systems may include projection,  monitor displays,  computers,  satellite connections video and audio playback devices,  and much more.

Can be observed when a white light beam passes through a triangular prism. The different wavelengths of light refract at different angles,  dispersing the light into its individual components.

A centralized housing unit that protects and organizes electronic equipment.

The number of times a cable can be bent before it breaks. A wire with more strands,  or more twists per inch,  will have a greater flex life than one with a lower number of strands,  or one with less twists per inch.

Abbreviated as fc or ft-c,  it is an English unit of measure expressing the intensity of light illuminating an object. The illumination from one candle falling on a surface of 1 square foot at a distance of 1 foot.

An informal, unstructured space where "ad hoc" meetings can be held, usually with a minimum of AV equipment.

A logarithm is the exponent of base 10 that equals the value of a number.

A system in a facility that allows for remote requests of content to be delivered from a head-end location.

A multipurpose test instrument with a number of different ranges for measuring current,  voltage,  and resistance.

Videoconferencing that links many sites to a common gateway service allowing all sites to see,  hear,  and interact at the same time; requires a bridge or bridging service. Also called continuous presence.

A test device that allows measurement of electronic signals by dynamically displaying the wave form of the signal.

A communication system where two sites are directly linked.

Maximum amount of tension that can be applied to a cable or conductor before it is damaged.

A unit of measure of the vertical space in a rack. One RU equals 1.75 inches (44.5 mm).

A relationship between two numbers indicating how many times the first number contains the second number.

Entertainment or business video and audio transmitted via a satellite.

When light hits a textured surface,  the incoming light waves get reflected in multiple angles because the surface is uneven.

The maximum force that a material can withstand before deforming or stretching.

A grouping or range of radio frequencies, i.e. "the 5 GHz Wi-Fi band."

An electrical disturbance caused by an electromagnetic field.

A threaded connector that is used in transmission applications such as cable television. The cable’s center conductor also serves as the connector’s center pin.

A condition where incident and reflected radio waves propagate from wireless audio/video transmitters to receiver, sometimes causing phase cancellation and audio drop-out.

The tendency of a radio transmission to interfere with other electronic signals.

A closed circuit system becomes an RF system when video and audio signals are modulated and tranmsitted at a certain frequency,  called a channel. RF systems require a display device (e.g. TV) with a tuner set to a selected channel to display the information modulated onto that frequency.

Satellite and Master Antenna Television system; a television system where satellite and broadcast programs are received via a master antenna array and distributed to users over coaxial cable or fiber optic cable.

An electronic device that divides a signal to route it to multiple devices.

The distance between two corresponding points of two consecutive cycles measured in meters. The wavelength of an RF signal is inversely proportional to its frequency.

An electric current that reverses its polarity (phase) at regular intervals.

An analog signal is any continuous signal for which the time-varying feature of the signal is a representation of some other time varying quantity. In an analog audio signal, the instantaneous voltage of the signal varies continuously with the pressure of the sound waves.

To reduce the amplitude (strength) of a signal or current.

A circuit in which two branches are electrically alike but inverted with respect to each other and symmetrical with respect to a common reference point,  usually ground. A balanced circuit has better noise immunity than a single-ended (unbalanced) circuit, due to its inherent high common-mode rejection ratio (CMRR).

An illustration of the signal path through a given system.

Stands for Bayonet Neill-Concelman connector. Used with coaxial cable to provide a uniform connection with minimal standing waves, as it is a constant impedance connector. Can be used at radio frequencies up to 3 GHz. Attaches to a matching jack with a bayonet (twist) action.

An electronic device that provides some isolation between other components. It can have unity or higher gain.

A wiring system that delivers power and data to various devices.

Concelman connector, developed at Amphenol Corporation as a constant impedance connector for large coaxial cables. It is a bayonet-action connector.

The ability of a material to accumulate and store an electrical charge from the voltage across it. Altough a material may be non-conductive, it can distort an electrical signal due to its capacitance (increasing with the signal frequency).

The opposition a capacitor offers to alternating current flow. Capacitive reactance decreases with increasing frequency or,  for a given frequency, the capacitive reactance decreases with increasing capacitance. The symbol for capacitive reactance is XC.

Sometimes called a Phoenix(R) connector,  it is a molded plastic connector whose termination requires that you strip and slide a wire directly into a slot on the connector. A set screw then pushes a gate down to hold the wire in place.

Enhanced version of the Cat-5 cable standard that adds specifications for far end crosstalk. (Part of the EIA/TIA 568A standard.)

Cable standard for Gigabit Ethernet and other interconnect that is backward compatible with Category 5 cable,  Cat-5e and Cat-3. Cat-6 features more stringent specifications for crosstalk and system noise. (Part of the EIA/TIA 568A standard.)

The ratio of the common-mode interference voltage at the input of a circuit,  to the corresponding interference voltage at the output.

Refers to either noise or surge voltage disturbances occurring between the signal and the ground conductor (green wire). Unwanted common mode disturbances may exist as a result of noise injection into the neutral or grounding wires,  wiring faults,  or overloaded power circuits.

The quality of being continuous (as in a continuous electrical circuit).

The rate at which electrical energy flows through a circuit.

Electronic device that extracts video and/or audio information from an RF-modulated signal.

A method of transmitting information by discrete,  non-continuous bits, usually in the form of data packets.

An electronic device that converts digital signals into analog form.

Electricity that maintains a steady flow and does not reverse polarity, unlike alternating current (AC). Usually provided by batteries,  AC to DC transformers,  and power supplies.

A generic name for D-shaped serial connectors used in data communications.

One of two common multi-pin connectors available for DVI signals. The DVI-D carries no analog video information,  only digital. The digital signal is limited to 5 meters.

One of two common multi-pin connectors available for DVI signals. The DVI-I adds analog video to the connection,  permitting greater distances than the digital limit of 5 meters.

Filters remove or pass certain frequencies in a signal.

Gigabits per second. Also notated as Gbps.

A frequency of one billion Hertz. Typically used to describe radio frequencies and pixel clock rates along with computer CPUs.

A frequency of one million Hertz. Typically used to describe radio frequencies and pixel clock rates along with computer CPUs.

A connector used with 4,  6,  or 8 pins. Common modular connectors are RJ-11 and RJ-45.

A type of optical fiber cable through which light waves travel with multiple reflections. Has a maximum transmission length of about 2 km (1.25 miles) @ 100 Mb/s and 550 m (1.3 mile) @ 1 Gb/s.

Neill connector, developed at Bell Laboratories as a constant impedance connector for large coaxial cables. It is a threaded connector.

A filter with a very narrow response characteristic that “notches out, ” or eliminates,  a specific frequency or band of frequencies.

A band or group of frequencies where the relationship between them is such that the lowest frequency is half that of the highest.

Defines the relationship between current,  voltage,  and resistance in an electrical circuit as proportional to applied voltage and inversely proportional to resistance. The formula is I=V/R. I = current (in amps),  V = voltage (in volts),  R = resistance (in Ohms).

The highest level of signal strength,  determined by the height of the signal’s waveform.

An adjustment method that allows compensation for high frequency loss in cables.

The position of a point in time (an instant) on a waveform cycle. Phase can also be an expression of relative displacement between two corresponding features of two waveforms having the same frequency.

A shorthand term used to describe the physical data rate of an interface. The "phy rate" for HDMI 2.1 is 12 Gb/s per lane, and for DisplayPort 1.4 is 8.1 Gb/s per lane.

The property of a material to impede the flow of electrical current,  expressed in ohms.

Refers to an analog video signal with separate conductors for the red signal,  green signal,  blue signal,  horizontal sync and vertical sync. VGA signals use the RGBHV format.

Recommended Standard 232 is a standard introduced in 1960 for the serial communication transmission of data.

Software Defined Video over Ethernet. A trade association of manufacturers who employ the Blue River NT system in their products.

A physical layer in some cables used to protect signals and sometimes used as a return path for current. There are three basic types of cable shielding: foil,  braid and combination.

Test equipment instrument that produces calibrated electronic signals intended for the testing or alignment of electronic circuits or systems.

A type of optical fiber cable where light waves travel in a single path with no reflections at distances up to 32 km (20 miles).

Small Microwave Adapter. A small, threaded constant impedance plug used for miniature coaxial cables and antennas. Commonly used with Wi-Fi routers and access points/cards.

A compilation of multiple individual AV components and sub-systems interconnected to achieve a communication goal.

Connections to a transformer or transmision line that let you extract different levels of power or signal energy.

A momentary variation in power such as a surge,  spike,  sag,  blackout,  noise,  or other type of transient.

Wires that are paired together and twisted around each other; can be shielded or unshielded.

Transmits the audio signal on a single conductor that is referenced to ground, typically in a coaxial wire structure. Also known as as a single-ended circuit.

Derived from the number 1. Unity gain indicates no change in gain through a system or device.

Universal Serial Bus, a high-speed serial data connection that can also carry power and work as a display interface.

A new, 24-pin compact and symmetrical version of the USB connector that can carry data, power, and display/audio signals simultaneously.

The basic international unit of potential difference or electromotive force; symbolized by an upper case "V".

The electrical potential to create current flow in a circuit.

A single conductive element intended to carry a voltage or electronic signal.

A standard for recording and playback of Full HD (1920x1080p) video, using a blue laser optical disc and H.264 AVC compression.

An International Telecommunications Union standard, Recommendation BT.2020, which defines a gamut of colors, a gamma curve, and a white point for high-dynamic range and wide color gamut video.

An International Telecommunications Union standard, Recommendation BT.709, which defines a gamut of colors, a gamma curve, and a white point for standard dynamic range video.

A type of sampling and compression that reduces the color information in a video signal in favor of luminance data to conserve signal bandwidth. 4:4:4 is equivalent to RGB, while 4:2:2 contains 1/3 less and 4:2:0 contains 1/2 less data than 4:4:4.

A video signal format where luminance, chrominance, and sync pulses all travel on one coaxial cable. Used only for standard-definition video.

A blurry appearance around the edge of an otherwise in-focus object (or the reverse) when the velocity of light going through the lens is different at the edges than at the center of the surface,  due to the lens design.

Digital Cinema Initiative. A set of specifications for formatting and display of digital movies. DCI also describes a gamut of display colors, also known as DCI P3.

The area in front of a camera lens that is in focus from the closest distance to the camera to the furthest distance.

An imaging copy stand used to capture a video image of printed documents or three-dimensional objects.

For interlaced video, one half of a video frame containing every other line of information. Two fields comprise a full interlaced video frame. For progressive video, one video field is the same as a video frame.

Abbreviated as FL,  it is the distance between the center of a lens and the point where the image comes into focus. The shorter the focal length,  the wider the angle of the image.

The act of adjusting a lens to make the image appear clear,  sharp,  and well-defined.

A video acquisition and display format having 1,920 horizontal and 1,080 vertical pixels. This can be an interlaced signal (1080i) or progressive-scan (1080p). Sometimes abbreviated as FHD.

High Definition Television.

The lens that focuses the image onto the screen.

Standard Definition Television.

A condition where light rays passing through the edges of a lens have a slightly different focal length from those passing through the center, creating an uneven focus across the image.

A video acquisition and display format having 3,840 horizontal and 2,160 vertical pixels.

An advanced version of Blu-ray, designed for recording and playback of Ultra HD video, using a blue laser optical disc and H.264 HEVC compression.