B C D
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H I J
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A procedure of adjusting the physical position of the CCD-chip/lens to
correct focus for all focal length settings (especially critical with
Back porch. 1.
The portion of a video signal that occurs during blanking from the end
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
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
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
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.
Bit Error Rate. The ratio of received bits that are in error
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
eg, a 1 bit error in 1 million
bits is a BER of 10-6.
Sony's domestic video recording format, a competitor of VHS, with
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
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
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.
A pixel-by-pixel description of an image. Each pixel is a
Also a computer file format for
Bit rate. Bps = Bytes
per second, bps = bits per second. The digital equivalent of
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.
A composite colour video signal. The signal has composite sync,
reference burst and a black video
Black level. A part
of the video signal, close to the sync level, but sometimes slightly
(usually 20 mV
- 50 mV) in order to be distinguished from the blanking level.
is called a
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
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 stands for Bayonet-Neil-Concelman connector, and it is the
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
Connector or Bayonet Nut Connector.
Bi-directionally predictive coded picture; an MPEG term for a picture
using motion compensated prediction
from a past and/or future reference
Braid. A number of
metallic strands interwoven to form a tubular structure that may
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
Ten cycles (PAL) or seven to nine cycles (NTSC) of
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,
Gigabyte (1,024 Megabytes
Petabyte (1,024 Terabytes
Exabyte (1,024 Petabytes
Zettabyte (1,024 Exabytes