|
Dictionary of Technical Terms - H
A B
C D E F G H
I J K L M
N O P Q R
S T U V W
X Y Z
Num
H
H
Henry. Also hexadecimal (H or h).
H
Horizontal. In television signals, may refer to any
of the following: 1. The horizontal period or rate. 2. The
horizontal line of video information. 3. The horizontal sync
pulse.
H & V lock time
The length of time it takes for a device to lock to
horizontal and vertical sync.
H blanking width
The width in terms of time occupied by horizontal
blanking. The period of time from the end of active video of one
line to the beginning of active video of the next line. During this
time, the electron beam in a camera or monitor is turned off as it
returns or retraces to the other side of the raster to begin a new
scan.
H drive (horizontal drive)
A pulse used to trigger the next horizontal line.
Generally a 2-4 volt negative-going pulse that typically starts at
the beginning of horizontal blanking and ends at the trailing edge
of sync.
H lock time
The length of time it takes for a device to lock to
horizontal sync.
H phase
1. The horizontal phase relationship of one piece of
equipment to another for studio timing purposes. 2. The phase of
horizontal sync in relation to subcarrier. See SC/H phase.
Hanover bars
An undesirable artifact of interlaced scanning that
looks like line-crawling venetian blinds.
hard black clip
Stops the composite video going below a
predetermined level.
hard disk
A digital data storage device using a rigid,
magnetic disk.
hard white clip
Stops the composite video going above a
predetermined level.
hard-wired
1. Electrical devices connected through physical
wiring. 2. Electronic programming technique using physical
connections and therefore essentially unalterable.
harmonic
A periodic wave having a frequency that is an
integral multiple of the fundamental frequency. For example, a wave
with twice the frequency of the fundamental frequency is called the
second harmonic.
harmonic distortion
The production of harmonics at the output of a
circuit when a periodic wave is applied to its input. The level of
the distortion is usually expressed as a percentage of the level of
the input.
HDTV
High definition television.
head end
The central point where cables originate in a cable
distribution system.
header
A type of connector typically having a rectangular
body made of plastic insulating material through which connecting
conductor pins protrude.
henry (H)
Unit of measurement of inductance. hertz
Unit of measurement for the number of cycles of a
waveform in one second. Cycles per second.
hi-con
High contrast, meaning high contrast video used as a
key source.
high frequency (HF)
The frequency bands from 3 to 30 MHz.
high frequency loss
Loss of signal amplitude at higher frequencies,
caused for example, by passing a signal through a coaxial
cable.
high impedance loop-through
See high Z looping input.
high level language
Any symbolic computer language that controls a
computer via commands that are similar to human language as opposed
to the numbers used in machine language.
high tally
Control panel button is lit to full brightness (as
opposed to dim), usually to indicate that the signal is on air.
high Z looping input
A high impedance input circuit which also includes
an output to enable routing the signal to another piece of
equipment.
hold-out matte
Area of a key where matte occurs behind the key.
hole cut
See key.
horizontal drive
See H drive.
horizontal (blanking) interval
The time period between lines of active video.
HORIZON™
A Grass Valley Group line of routing switchers
capable of handling a large number of inputs and outputs.
horizontal line
A single horizontal scan of a camera or CRT beam. A
number of these video scans together form a frame of video. There
are 525 interlaced lines per frame in NTSC, 625 in PAL.
horizontal period
The length of time for a complete horizontal line of
video information.
horizontal phase
See H phase.
horizontal resolution
Chrominance and luminance resolution (detail)
expressed horizontally across a picture tube. 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.
horizontal retrace
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.
horizontal sync pulse
The synchronizing pulse at the end of each video
line that determines the start of horizontal retrace.
house reference
See house sync.
house sync
Television sync generated within the studio and used
as a reference for generating and/or timing other video
signals.
hue (tint, phase, chroma phase)
One of the characteristics that distinguishes one
color from another. Hue defines color 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 color: See also
saturation and luminance. In NTSC and PAL 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 bars
Horizontal black and white bars that extend over the
entire TV picture and usually drift slowly through it. They are
caused by a power line interfering frequency or one of its
harmonics.
hum-bucker
1. A circuit (often a coil) that introduces a small
amount of voltage at power line frequency into the video path to
cancel unwanted AC hum.
hum rejection
In circuits, the ability to cancel interference in a
video or audio signal, often at the 50 or 60 Hz power line
frequency.
hum suppression
The cancellation of power line hum. See
hum-bucker.
hybrid circuit
A circuit that looks very much like a subminiature
printed circuit board and is composed of a mix of thick film and
surface mounted components. Hybrids make possible improved
performance, extended reliability, and economy of space. Use of
hybrids permits design of equipment such as entire processing
amplifiers (GVG 7510 Series) on single PC modules.
Hz
Hertz.
A B
C D E F G H
I J K L M
N O P Q R
S T U V W
X Y Z
Num
|