B C D
E F G
H I J
K L M
N O P
Q R S
T U V
HAD. Hole Accumulated
Diode. A type of CCD sensor with a layer designed to accumulate
holes (in the electronic sense),
thus reducing noise level.
HDD. Hard Disk Drive.
A magnetic medium for storing digital information on most
and electronic equipment that process
HDDTV. High Definition
Digital TeleVision. The upcoming standard of broadcast television
with extremely high resolution
and aspect ratio of 16:9. It is an advancement
from the analogue
high definition, already used experimentally
in Japan and Europe.
The picture resolution is nearly
2000×1000 pixels, and uses
the MPEG-2 standard.
Digital Subscriber Line. A digital transmission path that can be
used for the
transmission of CCTV pictures
(1 camera) at up to 2Mbps. Up to 5 cameras can be transmitted
but the data rate is shared (i.e.
384kbps for each camera).
HDTV. High Definition
TeleVision. It usually refers to the analogue version of the
Headend. The electronic
equipment located at the start of a cable television system, usually
including antennas, earth stations,
preamplifiers, frequency converters, demodulators,
and related cable transmission
Helical scan. A method
of recording video information on a tape that increases the "density"
of recorded information on tape,
when compared with linear recording. It is used commonly in
and professional VCRs.
Horizontal Drive (also Horizontal
sync). This signal is derived by dividing sub-carrier by
227.5 and then doing some pulse
shaping. The signal is used by monitors and
determine the start of each horizontal
Chrominance and luminance resolution (detail) expressed horizontally
across a picture tube, it is often
given as TeleVision Lines (TVL). This is usually expressed as
a number of black to
white transitions or lines that can
be differentiated. Limited by the
bandwidth of the video
signal or equipment.
caused by driving a colour-modulated composite video signal (PAL
into a monochrome monitor. It is also often a characteristic of
Interference (RFI) picked up along
a coaxial cable length.
At the end of each horizontal line of video, a brief period when the
scanning beam returns to the other
side of the screen to start a new line, sometimes called
Horizontal sync pulse.
The synchronizing pulse at the end of each video line that determines
the start of horizontal retrace.
Hertz. The unit that
measures the number of cycles per second. Named after Heinrich
Rudolph Hertz, a physicist.
Usually refers to the containment of the camera and lenses and
such as heaters, washers and wipers, to meet specific environmental
HS. Horizontal synchronization.
Hue (tint, phase, chroma phase).
One of the characteristics that distinguishes one colour from
another. Hue defines colour
on the basis of its position in the spectrum, i.e.,
whether red, blue,
green or yellow, etc. Hue
is one of the three characteristics of television
colour: see also Saturation
and Luminance. In PAL and
NTSC video signals, the
hue information at any particular point in the
picture is conveyed by the
corresponding instantaneous phase of
the active video subcarrier.
Hum. A term used to
describe an unwanted induction of mains frequency.
Humbug. A trade name
for an isolation transformer (to remove earth or ground loops).
Hyper-HAD. An improved
version of the CCD HAD technology, utilizing on-chip micro-lens
technology to provide increased
sensitivity without increasing the pixel