Glossary Of Spy ,Security and CCTV Cameras Terms and Definitions

GAIN
Gain is an increase or decrease in the strength of an electrical signal. An increase in voltage or power, usually expressed in dB.


GAMMA
A numerical value, or the degree of contrast in a television picture, which is the exponent of that power law which is used to approximate the curve of output magnitude versus input magnitude over the region of interest.

GHOST
A spurious image resulting from an echo.

HUM
Electrical disturbance at the power supply frequency or harmonics thereof.

INTERFERENCE
Extraneous energy which tends to interfere with the reception of the desired signals.

IRIS
An adjustable aperture built into a camera lens to permit control of the amount of light passing through the lens.

JITTER
Small, rapid variations in a waveform due to mechanical disturbances or to changes in the characteristic of components. Supply voltages, imperfect synchronizing signals, circuits, etc.

LUX
A unit measuring the intensity of light. The light of a full moon is about 0.1 lux, while bright sunlight is about 100,000 lux. Basically, the lower the rating the better the camera performs at night. 1.0 lux in video means light level of a candle light. l Lux approximately equals to 10 foot-candles (1 Lux = 10.764 fc). International System (Sl) unit of illumination in which the meter is the unit of length. One lux equals one lumen per square meter.
LENS
A transparent optical component consisting of one or more pieces of optical glass with surfaces so curved (usually Spherical), that they serve to converge or diverge the transmitted rays of an object, thus forming a real or virtual image of that object.

LENS SPEED
Refers to the ability of a lens to transmit light, represented as the ratio of the focal length to the diameter of the lens. A fast lens would be rated f/8. The larger the f number, the slower the lens.

LIGHT
Electromagnetic radiation detectable by the eye, ranging in wavelength from about 400 to 750 nm.

LOOP THROUGH
Also called looping. The method of feeding a series of high impedance circuits (such as multiple monitor/displays in parallel) from a pulse or video source with a coax transmission line in such a manner that the line is bridged (with minimum length stubs) and that the last unit properly terminates the line in its characteristic impedance. This minimizes discontinuities or reflections on the transmission line.

LOSS
A reduction in signal level or strength, usually expressed in dB. Power dissipation serving no useful purpose.

MONITOR
A unit of equipment that displays on the face of a picture tube the images detected and transmitted by a television camera.

M-JPEG
Motion Joint Photographic Experts Group. A compression technique for moving images which applies JPEG still image compression to each frame of a moving picture sequence. Playback requires a machine capable of decompressing and displaying each JPEG image quickly enough to sustain the required frame rate of the picture sequence. M-JPEG offers the highest resolution during playback, but is the least efficient in storage.

MULTIPLEXER (Mux)
A device that accepts video signals from a number of cameras and encodes them into one signal that is recorded on a digital recorder or VCR. The multiplexer also decodes the recording, so it can play back motion video from one camera at a time or several cameras all at once to one monitor. Many multiplexers also display several camera views at a time on a monitor while sending images to a recorder.

NOISE
Electrical energy or interference that appears on the screen as a grainy picture or "snow".

NTSC
National Television Standards Council. A video format standard used in North America, Japan, and parts of South America. Abbreviation for National Television Systems Committee. A committee that worked with the FCC in formulating standards for the present day United States color television system.

OUTPUT
The signal level at the output of an amplifier or other device.

PAL
Phase Alternating Current. A video format standard used in Europe, Australia, China, etc.

PIR
Passive infrared. A motion detector that senses body heat to detect motion.

PTZ
Pan Tilt Zoom. You will find some video cameras that allow these functions with a series of motors and special housings. Sometimes, you will find units that provide pan and tilt movements only.

PAN AND TILT
A device upon which a camera can be mounted that allows movement in both the azimuth (pan) and in the vertical plane (tilt).

PAN/TILT PRESET POSITIONING
Follower pots are installed on pan/tilt unit to allow feedback to the controller and provides information relevant to horizontal and vertical positioning, allowing the controller to quickly adjust to a pre-selected scene automatically.

PIXEL
Short for Picture Element. A pixel is the smallest area of a television picture capable of being delineated by an electrical signal passed through the system of part thereof. The number of picture elements (pixels) in a complete picture, and their geometric characteristics of vertical height and horzontal width, provide information on the total amount of detail which the raster can display and on the sharpness of the detail, respectively.

PRIMARY COLORS
Three colors wherein no mixture of any two can produce the third. In color television these are the additive primary colors red, blue and green.

RISC
Reduced Instruction Set Computer. Processors whose design is based on RISC provide a rapid execution of a sequence of simple instructions rather than on the provision of a large variety of complex instructions. This provides for faster decoding and simple addressing modes where more complex modes are replaced by sequences of simple arithmetic instructions.

RJ-45
A serial connector that looks very similar to a standard telephone connector, except that it houses eight wires instead of four.

RESOLUTION (HORIZONTAL)
The amount of resolvable detail in the horizontal direction in a picture. It is usually expressed as the number of distinct vertical lines, alternately black and white, which can be seen in a distance equal to picture height. A measure of the ability of the camera or monitor to reproduce detail. The higher the resolution the clearer the image.

RESOLUTION (VERTICAL)
The amount of resolvable detail in the vertical direction in a picture. It is usually expressed as the number of distinct horizontal lines, alternately black and white, which can theoretically be seen in a picture. A measure of the ability of the camera or monitor to reproduce detail. The higher the resolution the clearer the image.

ROLL
A loss of vertical synchronization which causes the picture to move up or down on a receiver or monitor.
Switcher
A device that switches views from several cameras to one or more monitors.

S/N (signal-to-noise) Ratio
The ratio between useful video signal and unwanted noise. The higher the number, the better the image quality.

SATURATION
In color, the degree to which a color is diluted with white light or is pure. The vividness of a color, described by such terms as bright, deep, pastel, pale, etc. Saturation is directly related to the amplitude of the chrominance signal.

SHUTTER
Ability to control the integration (of light) time to the sensor to less than 1/60 second; e.g: stop motion of moving traffic.

SIGNAL-TO-NOISE RATIO
The ratio between useful television signal and disturbing noise or snow.

SHOW
Heavy random noise.

SPIKE
A transient of short duration, comprising part of a pulse, during which the amplitude considerably exceeds the average amplitude of the pulse.

STANDARD MINIMUM SIGNAL
1000 microvolts at 75 ohms (0dB mV) in RF systems; 0.7-VPP non-composite, 1-VPP composite in video systems.

TCP/IP
Transmission Control Protocol / Internet Protocol. This two-layer protocol suite is the foundation for communication on the Internet. Any computer or device that wants to communicate over the Internet must use the TCP/IP protocol stack. TCP provides reliable delivery of information with the ability to correct errors during transmission as well as provide a variety of other reliable features to ensure proper data transfer. IP provides the logical addressing system for any device on a network, ensuring that each unit is identified so communication can take place. Being connectionless, IP treats each individual packet (chunk of data) as a single unit, providing source and destination addresses so each networked device that receives that packet can determine where the packet originated and where it is destined to go. IP does not care whether the information got there or how it got there, that is why TCP and IP must work together. Usually uses a client/server architecture where one device (the client) requests information from another device that supplies the wanted information (the server).

TWISTED PAIR
A cable composed of two small, insulated conductors twisted together. Since both wires have nearly equal exposure to any interference, unwanted noise is substantially reduced.

TEARING
A term used to describe a picture condition in which groups of horizontal lines are displaced in an irregular manner.

TEST PATTERN
A chart especially prepared for checking overall performance of a television system. It contains various combinations of lines and geometric shapes. The camera is focused on the chart, and the pattern is viewed at the monitor for fidelity.

VARIFOCAL LENS
A lens that can be manually adjusted for the desired magnification and field of view.

VERTICAL RESOLUTION
The number of horizontal lines that can be seen in the reproduced image of a television pattern.

WHITE BALANCE
A process used in video cameras to retain true colors.

ZOOM
To enlarge or reduce, on a continuously variable basis, the size of a televised image primarily by varying lens focal length.

ZOOM LENS
An optical system of continuously variable focal length, the focal plane remaining in a fixed position.