Glossary Q-T

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A device that compresses up to four video signals and simultaneously displays the images onto one monitor.


Rack Mount

An industrial standard housing 19" wide, its height is measured in units (U’s) of 1.75".

Radio Frequency (R.F.)

Signals with a repetition rate above audible range, but below the frequencies associated with heat and light.


Redundant Arrays of Independent Disks. The use of two or more disk drives instead of one disk, which provides better disk performance, error recovery, and fault tolerance, and includes interleaved storage techniques and mirroring of important data.

Random Interlace

A scanning technique commonly used in CCTV systems in which there is no external control over the scanning process. That is, there is no fixed relationship between adjacent lines and successive fields.


The rectangular pattern of scanning lines upon which the picture is produced. The illuminated face of the TV monitor without the video information present.

RCA aka RCA Jacks

A common connector plug for standard consumer video and audio equipment. This type of connector plug may also be described as a "phono" plug. RCA jacks are found on all VCRs and televisions equipped to handle a composite and component video.

Realtime (or real time)

Refers to video recorded at the same speed as action occurs (so it may be played back at the speed of real time without drag). Realtime video is phased at 30 frames per second (60 fields per second) for NTSC video and 25 frames per second (50 fields per second) for PAL format equipment.


Any component that receives, or tunes, broadcast signals, be it NTSC, HDTV, DBS, or AM/FM radio. Typically refers to the single component that includes a preamp, surround processor, multichannel amplifier, and AM/FM tuner.

Remote Playback

A feature of many DVR and NVR recorders. This allows users to play back recorded video over the internet from virtually any computer in the world.


A measure of the ability of a camera or television system to reproduce detail. Typically refers to the number of picture elements that can be reproduced with good definition.

Resonant Frequency

The frequency at which any system vibrates naturally when excited by a stimulus. A tuning fork, for example, resonates at a specific frequency when struck.


Root Mean Square or the square root of the arithmetic mean (average) of the square's set of values. A reasonably accurate method of describing an amplifier's power output.


Rear-Projection Television


A format of digital communication where only two wires are required. It is also known as a serialdata communication. The RS-232 standard defines a scheme for asynchronous communications, but itdoes not define how the data should be represented by the bits, i.e., it does not define the overall messageformat and protocol. It is very often used in CCTV communications between keyboards and matrixswitchers or between matrix switchers and PTZ site drivers. The advantage of RS-232 over others is itssimplicity and use of only two wires.


This is an advanced format of digital communication when compared to RS-232. The basicdifference is in the need for four wires instead of two as the communications is not single-ended as withRS-232, but differential. In simple terms, the signal transmitted is read at the receiving end as thedifference between the two wires without common earth. So if there is noise induced along the line, it willbe cancelled out. The RS-422 can drive lines of over a kilometer in length and distribute data to up to 10receivers.


This is an advanced format of digital communications compared to RS-422. The majorimprovement is in the number of receivers that can be driven with this format, and this is up to 32.


S.E.C.A.M. (See CCIR)

Color TV system used in France.

S/N Ratio (Signal To Noise Ratio)

Measure of noise levels of a video signal; the higher the number the better.

Saturation (Color)

The vividness of a color. It is directly related to the amplitude of the chrominance signal.

Scotopic vision

Illumination levels below 10–2 lux, thus invisible to the human eye.


Small Computer Systems Interface (Pronounced "scuzzy".) A ultra high-speed interface that can connect to computer devices such as a hard drive or CD-Rom. A SCSI channel can connect up to seven devices.


Sequential Couleur Avec Memoire, sequential color with memory. A color television system with625 lines per frame (used to be 819) and 50 fields per second developed by France and the former U.S.S. R. Color difference information is transmitted sequentially on alternate lines as an FM signal.


A cameras ability to reproduce a given scene with a given amount of light. Usually expressed in foot-candles or lux.

Sequential Switchers

Are commonly used devices in small to medium sized CCTV systems. The sequential switcher alternates the displayed video image from one camera to the next. However, with sequential switching not all cameras can be viewed simultaneously.

Simplex (Multiplexer)

A multiplexer with 1 frame store that can either time multiplex records or show multi-screen pictures in live or play back. It cannot record the multiplexer pictures whilst showing multi-screen pictures.

Single-mode fiber optics

An optical glass fiber that consists of a core of very small diameter. A typical single- mode fiber used in CCTV has a 9 mm core and a 125 mm outer diameter. Single-mode fiber has lessattenuation and therefore transmits signals at longer distances (up to 70 km). Such fibers are normallyused only with laser sources because of their very small acceptance cone.

Smart Card

Smart cards have an embedded computer circuit that contains either a memory chip or a microprocessor chip. There are several types of smart cards: Memory, Contact, Contactless, Hybrid (Twin), Combi (Dual Interface), Proximity and Vicinity.

Standard Cards

The standard card size is CR-80. CR-80 dimensions are 3.375" x 2.125" (85.6 mm x 54 mm).

Static IP Address

A Static or Dedicated IP address is a type of account from an ISP where your computer or network is assigned the same constant IP Address at all times. Also see IP Address and Dynamic IP.


A device used to switch the video signals from two or more cameras on a monitor.


Super HAD (Hole Accumulation Diode) CCDs allow more light to pass to each pixel, increasing sensitivity and reducing noise.



A digital transmission link with a capacity of 1.544 Mbps. T1 uses two pairs of normal twisted wires. T1lines are used for connecting networks across remote distances. Bridges and routers are used to connect LANs overT1 networks.


A picture condition in which horizontal lines are displaced in an irregular manner.


A lens used to produce a larger image of a distant object.

Terminated (75 Ohm Terminated)

Video input of a piece of CCTV equipment, wired to be the last in a particular video line.


The up and down tilting movement of a camera. To elevate or depress the vertical angle of view.

Timebase Corrector (T.B.C.)

Electronic circuit that aligns unsynchronized video signals before signal processing. Used in multiplexers and quad splitters.

Time-Lapse Recording

Video recorder (VCR,DVR,NVR) that can record frames with pauses between them thereby extending the time that a standard length tape will last.

Triplex (TM)

Multiplexer feature that gives you the ability to simultaneously view both playback and live cameras within the same multi-screen, while still encoding.

Twisted Pair

A cable, often screened, that consists of two conductors twisted together along their length

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