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B
Back-focus.  A procedure of adjusting the physical position of the CCD-chip/lens to
achieve the correct focus for all focal length settings (especially critical with zoom lenses).
Back porch.  1.  The portion of a video signal that occurs during blanking from the end of
horizontal sync to the beginning of active video.
2.  The blanking signal portion that lies between the trailing edge of a horizontal sync pulse
and the trailing edge of the corresponding blanking pulse.  In CCIR and PAL it is 5.8µs long.
Chroma burst is located in the back porch.
Balanced signal.  In CCTV this refers to a type of video signal transmission (or data
transmission) through a twisted pair cable.  It is called balanced because the signal travels
through both wires in anti-phase, with no reference to Earth, thus being equally exposed to
the external interference, common mode interference is cancelled out.  It needs a differential receiver.
Balun.  This is a transformer used to match or transform an unbalanced coaxial cable to a balanced
twisted pair system, or visa versa.
Bandwidth.  The complete range of frequencies over which a circuit or electronic system can
function with minimal signal loss, usually measured between the 3 dB points (half power) at
each end of the frequency spectrum.  In PAL systems the bandwidth is generally accepted as 5.5MHz.
Baseband.  The frequency band occupied by the aggregate of the signals used to modulate a
carrier before they combine with the carrier in the modulation process. In CCTV the majority of signals
are in the baseband.
Baud.  The rate at which data is transferred.  Named after Maurice Emile Baud.  The Baud rate is
equivalent to bits per second in cases where each data event represents exactly 1 bit.
To communicate the baud rates of the equipment must be set the same. Note the baud rate and bit
rate in a system can be different.
BER.  Bit Error Rate.  The ratio of received bits that are in error relative to the total number of
bits received bit stream.  The BER is expressed as a powers of 10 (usually multiples of 3 ie k, M etc)
eg, a 1 bit error in 1 million bits is a BER of 10^-6.
Betamax.  Sony's domestic video recording format, a competitor of VHS, with better resolution in
colour.  The format is still popular in the USA.
Bias.  Current or voltage applied to a circuit to set a reference operating level for proper
circuit performance, such as the high frequency bias current applied to an
audio recording head to improve linear performance and reduce distortion.
Binary.  A base 2 numbering system using the two digits 0 and 1 (as opposed to ten digits
[0-9] in the decimal system).  In computer systems, the binary digits are represented by two different
voltages or currents, one corresponding to zero and another corresponding to one, positive logic uses
a positive voltage to represent binary 1 and zero volts to represent binary 0.
Bipolar.  A signal containing both positive-going and negative-going amplitude.  May also
contain a zero amplitude state.
Bit.  A contraction of BInary digiT.  Elementary digital information that can only be 0 or 1.
The smallest part of information in a binary notation system.  A bit is a single 1 or 0.  In
computer terms, a group of 4 bits is a nibble, 8 bits is a byte and 16 bits a word.
Bitmap (BMP).  A pixel-by-pixel description of an image.  Each pixel is a separate element.
Also a computer file format for pictures.
Bit rate.  Bps = Bytes per second, bps = bits per second.  The digital equivalent of bandwidth,
bit rate is measured in bits per second.  It is used to express the rate at which the compressed
bitstream is transmitted.  The higher the bit rate, the more information that can be carried.
Blackburst (colour-black).  A composite colour video signal.  The signal has composite sync,
reference burst and a black video signal.
Black level.  A part of the video signal, close to the sync level, but sometimes slightly above it
(usually 20 mV - 50 mV) in order to be distinguished from the blanking level.  This is called a
pedestal.  It electronically represents the black part of an image,  whereas the white part is
equivalent to 0.7 V from the sync level.
Blanking level.  The beginning of the video signal information in the signal's waveform.  It
resides at a reference point taken as 0 V, which is 300 mV above the
lowest part of the sync pulses.
Blooming.  The defocusing of regions of a picture where brightness is excessive.
BNC.  BNC stands for Bayonet-Neil-Concelman connector, and it is the "standard" connector
in CCTV and broadcast TV for transmitting a basic bandwidth video signal over a coaxial cable.
It can also be used as abbreviations for British Naval Connector or Bayonet Nut Connector.
B-picture.   Bi-directionally predictive coded picture; an MPEG term for a picture that is coded
using motion compensated prediction from a past and/or future reference picture.
Braid.  A number of metallic strands interwoven to form a tubular structure that may be
applied over one or more wires or flattened to form a strap.
Brightness.  In PAL and NTSC video signals, the brightness information at any particular
instant in a picture is conveyed by the corresponding instantaneous DC level of active video.
Brightness control is an adjustment of setup (black level, black reference).
Burst (colour burst or chroma burst).   Ten cycles (PAL) or seven to nine cycles (NTSC) of
sub-carrier placed near the end of horizontal blanking to serve as the phase (colour) reference
for the modulated colour sub-carrier.  It enables the monitors' Phase Locked Loop to synchronize
and track the change of phase during every line of video.
Bus.  In computer terminology, a path (often bi-directional) over which binary data travels
internally among the various components of a system and is available to each of the components
connected to the bus.
Byte.  Is 8 binary bits (ones and zeroes).   The greater multiples of bytes are shown below
     Kilobyte (1,024 bytes)
     Megabyte (1,024 kilobytes, 10488576)
     Gigabyte (1,024 Megabytes 1073741824 bytes)
     Terabyte (1,024 Gigabytes  1099511627776 bytes)
     Petabyte (1,024 Terabytes 1125899906842624 bytes)
     Exabyte (1,024 Petabytes 1152921504606846976 bytes)
     Zettabyte (1,024 Exabytes 1180591620717411303424 bytes)
     Yottabyte (1,024 Zettabytes 1208925819614629174706176 bytes)
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