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The Glossary

An all inclusive glossary of security lingo is provided for your convenience. This list
will undoubtedly be helpful when delving in to the realm of security.

T:

T1 - A digital transmission link with a capacity of 1.544 Mbps. T1 uses two pairs of normal twisted wires. T1
lines are used for connecting networks across remote distances. Bridges and routers are used to connect
LANs overT1 networks.
T1 channels - In North America, a digital transmission channel carrying data at a rate of 1.544 million bits
per second. In Europe, a digital transmission channel carrying data at a rate of 2.048 million bits per
second. AT&T term for a digital carrier facility used to transmit a DS-1 formatted digital signal at 1.544 Mbps
T3 channels - In North America, a digital channel that communicates at 45.304 Mbps commonly referred to
by its service designation of DS-3.
TBC - Time base correction. Synchronization of various signals inside a device such as a multiplexer or a
time base corrector.
TDG - Time and date generator.
TDM - Time division multiplex. A time-sharing of a transmission channel by assigning each user a
dedicated segment of each transmission cycle.
Tearing - A lateral displacement of the video lines due to sync instability. It appears as though parts of the
images have been torn away.
Teleconferencing - Electronically linked meeting conducted among groups in separate geographic
locations.
Telemetry - Remote controlling system of, usually, digital encoded data, intended to control pan, tilt, zoom,
focus, preset positions, wash, wipe and similar. Being digital, it is usually sent via twisted pair cable or
coaxial cable together with the video signal.
Termination - This usually refers to the physical act of terminating a cable with a special connector, which
for coaxial cable is usually BNC. For fiber optic cable this is the ST connector. It can also refer to the
impedance matching when electrical transmission is in use. This is especially important for high
frequency signals, such as the video signal, where the characteristic impedance is accepted to be 75-W.
TFT - Thin-film-transistor. This technology is used mainly for manufacturing flat computer and video
screens that are superior to the classic LCD screens. Color quality, fast response time and resolution are
excellent for video.
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 2.275 cm/s (which is the case with the domestic models of VHS VCRs), it moves with discrete
steps that can be controlled. Time Lapse VCRs have a number of other special functions very useful in
CCTV, such as external alarm trigger, time and date superimposed on the video signal, alarm search and
so on.
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 in reference to a 3-hr (180-min) tape. Time
multiplexing. The technique of recording several cameras onto one time lapse VCR by sequentially
sending camera pictures with a timed interval delay to match the time lapse mode selected on the recorder.
T-pulse to bar - A term relating to frequency response of video equipment. A video signal containing equal
amplitude T-pulse and bar portions is passed through the equipment and the relative amplitudes of the T-
pulse and bar are measured at the output. A loss of response is indicated when one portion of the signal
is lower in amplitude than the other.
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 fiber 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 up linked 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 of digital equipment. Such compatibility eliminates the
need for interfacing circuitry. TTL signals are usually limited to two states, low and high, and are thus much
more limited than analog signals.
2. Thru-the-lens viewing or color measuring.
Twisted-pair - A cable composed of two small insulated conductors twisted together. Since both wires
have nearly equal exposure to any interference, the differential noise is slight.

Courtesy of CCTV Labs and CCTV focus magazine

Glossary