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Back-EMF (Back-Electromotive Force)
Occurrence in which a speaker driver continues moving after the amplifier signal stops moving the voice coil back through the magnetic field and creating its own voltage which flows back to the amplifier and creates a flopping effect in the speaker driver.
Back focus.
The distance between the lens and the pickup chip; to remain in focus while zooming, the lens' back focus must be adjusted precisely. Also, the act of adjusting a lens' back focus.
Background generator
SEG circuit that adds colour to a black background, useful for keying words onto a coloured background.
Backhaul
The act of sending a program or newsfeed via satellite from a local area back to the main distribution area for rebroadcasting via satellite.
Baffle.
Front panel of a speaker enclosure on which the drivers are placed.
Balance.
The degree to which two or more sound sources present an equal sound pressure level (equal loudness) when driven with the same material
Balanced.
Balanced wiring in electronics refers to wiring with two conductors in addition to a wire shield
Banana Connector.
A speaker wire termination consisting of a single, fat shaft which bulges on the sides similar to a banana and inserts in 5-way binding posts.
Band 1.
  1. A grouping of frequencies in the audible frequency spectrum.
  2. A range of radio frequencies used for a certain type of communications.
  3. A set of related frequencies. UHF (ultrahigh frequency) is one band 470-890 MHz (megahertz).
Banding.
A picture artifact or fault whereby smooth brightness or colour gradients appear to be comprised of bands of brightness or colour, often the result of too few bits used to represent each sample of a picture. Banding could make a billiard ball look like a sliced onion.
Bandpass Enclosure.
A type of speaker enclosure used with subwoofers to produce large amounts of bass with minimal power input by utilizing essentially a sealed subwoofer enclosure mated to a ported box.
Bandwidth.
  1. The frequency range across which an audio system can reproduce sound.
  2. The width of the band over which frequencies are transmitted. A band is a portion of the electromagnetic spectrum, defined by the lowest and highest frequencies in it. The bandwidth is the difference between the highest and lowest frequencies. The greater the bandwidth, the greater the carrying capacity.
  3. The range of frequencies over which a circuit or electronic device can function properly. NTSC bandwidth is 4.2 MHz, meaning the signals can have frequencies ranging between 0 vibrations per second and 4.2 million vibrations per second.
Bank.
A storage location in a sampler or synthesizer that typically holds a large number of individual program (sounds).
Barn doors.
Metal flaps on a lighting instrument that can be closed or opened to direct the light, and shade areas where light is undesirable.
Barrel connector.
An adapter with a socket at each end which allows two cables to be connected together.
Barrel Distortion.
Form of video distortion in which lines on the screen bow or bend outward toward the edges of the screen when they should be straight lines with no curve (or curved lines are curved more than they should be).
Baseband.
The most common type of network. Data is transmitted digitally, each wire carrying one signal at a time.
Bass.
  1. The deepest frequencies of the audible spectrum - generally those below 200 Hz.
  2. Low frequency sound.
Bass Reflex.
Type of speaker enclosure which uses a port to increase bass output for a given power input resulting in 2 to 3 dB (decibels) more sound pressure than a similar sealed enclosure (also known as an acoustic suspension enclosure).
Baud.
Bits per second transmitted or received by a modem.
Bayonet Mount.
Lens-to-camera connection popular on professional cameras.
Beaded Screen.
Projection screen covered with tiny glass beads (looks like white sandpaper); has a gain of 2 or 3.
Beaming.
Term used to describe a sonic characteristic in which high frequency sounds produced by an audio system tend to be too loud and harsh or grating with a distinct directional component.
Beta (Betamax).
Consumer video format developed by Sony during the 1980's and eventually dropped for VHS.
Betacam.
Portable, professional camera/recorder format developed by Sony. Betacam uses a component video system.
Betacam SP.
  1. A superior performance version of Betacam. SP uses metal particle tape and a wider bandwidth recording system.
  2. Component VCR format using Betacam cassettes.
  3. Improved version of betacam, downwardly compatible with it, very popular among professionals.
Bezier Patch.
Grid upon which flat objects are "pasted". By stretching or bending the grid, objects will stretch, bend, or morph.
Bi-amplify.
Technique in audio where the high frequency drivers in a speaker are driven or powered separately from the low frequency drivers used in the same speaker through the use of dual binding posts on the speakers and multiple amplifiers.
Bias.
A high frequency signal added to an audiotape in order to reduce distortions.
Binary.
Counting system based on two levels, 0 and 1, used by computers and other digital equipment.
Binding Post.
A means of connecting speaker wire to an amplifier or speaker.
Bipolar Speaker.
Type of loudspeaker that directs sound in two directions using speaker driver on two sides of the enclosure opposite one another operating in phase (meaning that they both push out at the same time and they both come in at the same time).
Bipolar Transistor.
Transistor (transistor being a semiconductor capable of amplification) designed like a sandwich with semiconducting material on either side of a "base" semiconductor in the middle (the semiconducting material used for the base is different from that used for the "sandwich bread" one being p type and one being n type); bipolar transistors are commonly found in high-end amplifiers.
BIOS
Basic Input / Output System. An essential part of the operating system used to handle communication between a computer and its peripherals. A PC BIOS is stored in ROM. It checks that all required hardware components such as memory, disc drives and keyboards are present, loads key parts of the operating system and tells it what hardware is available.
BITS (BYTES).
A binary digit. Mode of information used by a computer to store numbers. One bit equals a \Qone' or a \Qzero'. Usually 8 bits equals one byte, however, MIDI uses a 10 bit-byte that includes a start bit, the 8 - bit data message, and a stop bit.
Bit Depth.
Bit depth measures how much colour information is available to display or print each pixel in an image. The greater bit depth means more available colours and more accurate colour representation in the digital image. For example, a pixel with a bit depth of 1 has two possible values: black and white. A pixel with a bit depth of 8 has 256 possible values.
Bit Rate.
The number of bits transferred in one second by a digital device such as a CD player.
Bitmap.
Image stored as pixels mapped across the screen.
Bi-wire.
Technique used in connecting speakers to amplification sources in which two wires are run from each amplifier terminal to the corresponding speaker terminal instead of one.
Black a tape.
The process of recording a black burst signal across the entire length of a tape. Often done before recording edited footage on the tape to give the tape clean, continuous video and sync and to insure there is no video already on the tape.
Black balance.
Colour camera adjustment which makes blacks pure black (not tinted one colour or another).
Black burst.
A composite colour video signal comprised of sync, colour burst and black video. It is used to synchronize (genlock) other video sources to the same sync and colour information. Black burst generators are used in video studios to "lock" the entire facility to a common signal ("house sync" or "house black").
Black Level.
The level of brightness at the darkest (black) part of a visual image or the level of brightness at which no light is emitted from a screen resulting in pure black.
Blanking.
One of the sync signals that determines the size of the black sync bar at the bottom of the TV picture.
Blanking level.
Also known as the pedestal, it is the voltage level produced at the end of each horizontal picture line which separates the portion of the video signal containing the picture information from the portion containing the synchronizing information. This voltage makes the electron beam "invisible" as it moves to draw the next visible line.
Blanking Interval (Horizontal & Vertical).
The horizontal blanking interval is the time between the end of one scanning line and the beginning of the next. The vertical blanking interval is the time between the end of one video field and the beginning of the next. Blanking occurs when a monitor's electron beam is positioned to start a new line or a new field. The blanking interval is used to instantaneously reduce the beam's amplitude so that the return trace is invisible.
Bleeding.
Video term referring to an image error where the colour from one object in an image seeps into the object or objects next to it in the same image.
Blooming.
Video distortion caused by an excessive level of brightness resulting in images which are too large or exaggerated in size and are overly soft having lost a degree of focus.
Blue Gun.
Used with colour bar test signals, this calibration switch on a TV monitor activates only the electron guns for the blue phosphors; for adjusting colour hue and saturation. Blue pedestal Control on a colour camera CCU which adjusts the amount of blue signal the camera makes when it "sees" no blue. Similar controls for red and green may exist. Used in balancing black levels.
Bluetooth
Specification for linking devices such as mobile phones, computers and PDA( Personal digital assistants) over a short range wireless connection. The maximum range which it can operate is currently 10m, with data transfer rates of up to 721Kbps supported.
BMP.
Bitmap format for an image file, capable of handling 16 colours, 256 colours, or True colour. BMPs are a subset of Windows DIB format, but do not support image compression.
Boundary Effects.
Reverberations and sound irregularities caused by sound waves bouncing off hard surfaces, namely walls, floors and ceilings.
Bowing.
Form of video distortion characterized by lines that should be straight curving or bending.
Bps.
Bits per second, the speed data travels through a wire or device.
BRI Basic Rate Interface,
ISDN phone line with two 64kbps channels and one 16kbps channel.

Bridge (Bridging).
Amplification term used to describe the process whereby two channels of amplification are combined to operate as a single mono channel.
Bright Sound.
Having a quality having a harsh or brittle high-end with too much focus on the upper frequencies.
Broadband.
Describes analogue transmission over a wire that can carry multiple signals at once. Cable TV uses broadband transmissions.
Buffer.
An area of RAM used to temporarily store data.
Butterworth Crossover.
Type of crossover that uses a low-pass filter design, which results in no amplitude anomalies in the frequencies passed on by the filter (the passband).
Burn in.
A spot, streak, or blemish on the TV screen which remains even when the camera is focused on a new scene. TV screen burn-ins are usually caused by displaying a contrasty object for too long. Aiming the camera at a very bright object like the sun can burn-in the CCD chip.
Burst.
Part of the sync signal controlling the hue and colour accuracy of TV pictures. It is a reference signal used by TVs and other video equipment as the benchmark for what all the hues should be.
Burst Phase.
Control on a colour camera CCU (or other video gear) that adjusts the timing of the burst signal and thus varies the colour hues in the picture.
Bus.
A communication pathway connecting two or more devices

Bus Structure
Bus lines classified as: data, address and control.
There are a number of possible interconnection systems. Single and multiple BUS structures are most common.

Bus Interconnection Scheme.
What do buses look like ?

  1. Parallel lines on circuit boards
  2. Ribbon cables
  3. Strip connectors on mother boards
    e.g. PCI
  4. Sets of wires
Butterfly or Overhead.
Large sheet of diffusion material usually erected like a tent over the subject to soften light.
Byte.
Eight bits, usually the number of bits necessary to represent an alpha numeric character like the letter A (which happens to be 01000001).

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