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H I J
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Q R S
T U V
In North America, a digital transmission channel carrying data at a
In Europe, a digital transmission channel carrying
data at a rate of 2.048
TBC. Time Base Correction.
Synchronization of various signals inside a device or
system, such as a
multiplexer or a time base corrector.
Transmission Contorl Protocol / Intenet Protocol
TDG. Time and Date
TDM. Time Division
Multiplexing. Time-sharing of a transmission channel by assigning
a dedicated segment of each transmission cycle. Video
use TDM techniques to record many
signals onto a single tape.
Tearing. A lateral
displacement of the video lines due to sync instability. It
parts of the images have been torn
Electronically linked meeting conducted among groups in separate
data used for the remote control (or monitoring) of a system.
digital encoded data, which is
represented by voltages on the line. Sometimes the signal
can be audio tones, such as Frequency
Shift Keying (FSK) or Dual Tone Multi Frequency
(DTMF). It is intended to
control pan, tilt, zoom,
focus, preset positions, wash, wipe and
digital, it is usually sent via twisted
pair cable but it can also be transmitted
over the video coaxial cable, in
the opposite direction to the video.
Telephoto. A lens
where the focal length is longer than the physical length of the
to be confused with a zoom lens.
1. The connection of a discreet impedance at the end of a transmission
When the characteristic impedance
of the cable (75 Ohms in CCTV) is the value used (as
should always be the case) the
maximum power is transferred with no reflections.
2. It can refer to the physical
act of terminating a cable with a special connector,
coaxial cable is usually BNC.
For optical fibre cable, the most common Termination in CCTV
is the ST connector.
This technology is used mainly for manufacturing flat computer
and video screens that are superior
to the classic LCD screens. Colour quality,
time and resolution are excellent
Time lapse VCR (TL VCR).
A video recorder, most often in VHS format, that can prolong
the video recording on a single
tape up to 960 hours (this refers to a 180
min tape). This
type of VCR is often used in CCTV
systems. The principle of operation is
very simple -
instead of having the video tape
travel at a constant speed
of just under 24mm/s (which
the case with the domestic models
of VHS VCRs), it moves with
discrete steps that can
controlled. TL VCRs can have
a number of other special
functions for use in CCTV systems.
Time lapse video recording.
The intermittent recording of video signals at intervals to extend
the recording time of the recording
medium. It is usually measured when using a 3-hr
T-pulse to bar. A
term relating to frequency response of video equipment. A video
containing equal amplitude T-pulse
and bar portions is passed through the equipment
relative amplitudes of the T-pulse
and bar are measured at the output. A
loss of response is
indicated when any portion of the
signal is lower in amplitude
than the other.
The test signal
is called a Pulse and Bar
signal and often includes a 2T a 10T a bar and a ramp signal, which
contains low medium and high frequencies.
Touchscreen. A computer
type screen that enables selection similar to a computer mouse but
operates by touching the screen.
The operation is usually either based on capacitance or
Surface Acoustic Waves (SAW).
Tracking. The angle
and speed at which the tape passes the video heads.
Transcoder. A device
that converts one form of encoded video to another, e.g., to convert
NTSC video to PAL. Sometimes
mistakenly used to mean translator.
Transducer. A device
that converts one form of energy into another. For example, in
optics, a device that converts
light signals into electrical signals.
Translator. A device
used to convert one component set to another, e.g., to convert Y, R-Y,
B-Y signals to RGB signals.
Transponder. The electronics
of a satellite that receives an uplinked signal from the earth,
amplifies it, converts it to a
different frequency and returns it to the earth.
TTL. 1. Transistor-Transistor
Logic. A term used in digital electronics mainly to describe the
ability of a device or circuit
to be connected directly to the input or output
equipment. Such compatibility
eliminates the need for interfacing circuitry. TTL
are usually limited to binary i.e..
two states, low and high, and are thus much
than analogue signals. 2.
Thru-The-Lens viewing, metering or colour measuring.
TVL. TeleVision Lines.
The measure of resolution of either a camera output or a monitor
display. It is limited by
the frequency response of the system or the Chroma sub carrier.
Twisted-pair. A cable
composed of two small insulated conductors twisted together. Since
both wires have nearly equal exposure
to any interference, common mode noise is high, but
the differential noise is slight
thus common mode noise is rejected in a twisted pair line. Twisted
pair cable is used for balanced line transmission.