| Word | Description |
| Tearing | A term used to describe a picture condition in which groups of horizontal lines are displaced in an irregular manner. |
| Telemetry | Control of PTZ cameras is provided using Telemetry Control. This signal is sent down 'twisted pair' cable or along the same coaxial cable the video signal is being sent down. Typical Telemetry signals are RS-485 or RS-422. |
| Telephoto | A lens where the focal length is longer than the physical length of the lens, not to be confused with a zoom lens. |
| Termination | 1. The connection of a discreet impedance at the end of a transmission line. 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, which for coaxial cable is usually BNC. For optical fibre cable, the most common Termination in CCTV is the ST connector. |
| TFT | Thin-Film-Transistor. This technology is used mainly for manufacturing flat computer and video screens that are superior to the classic LCD screens. Colour quality, fast response time and resolution are excellent for video. |
| TS | Time Sensitiivty. The length of time required for an object to remain in the detection zone to trigger an event. |
| 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. |