Glossary Of Spy ,Security and CCTV Cameras Terms and Definitions

AGC
Automatic Gain Control. When enabled, the camera's sensitivity is automatically increased when the level of ambient light drops. Automatic Gain Control. A circuit for automatically controlling amplifier gain in order to maintain a constant output voltage with a varying input voltage within a predetermined range of input-to-output variation.

APERTURE
The aperture of a lens controls the amount of light which can reach the pickup device (image sensor when relating to video). The size is controlled by the iris adjustment. By increasing the F-number (F1.2, F1.8, etc), less light will be permitted into the sensor.

ATC
Auto-tracking White Balance. This is a white balance feature that accepts many types of lighting conditions by using an automatic tracking system that automatically controls the color temperature range from 2,400K to 10,000K. ATW mode ensures reliable color reproduction when lighting conditions change frequently.

AUTO IRIS
Automatic method of varying the size of the lens aperture in response to changes in light. This is a function of the lens or the camera

AWC
Preset White Balance. AWC is suitable where a lot of white objects appear in the scene. Also it is suitable for situations where the object merges into the scene with a similar color shade.

AUTO BALANCE
A system for detecting errors in color balance in white and black areas of the picture and automatically adjusting the white and black levels of both the red and blue signals as needed for correction.

AUTOMATIC BRIGHTNESS CONTROL
In display devices, the self-acting mechanism which controls brightness of the device as a function of ambient light.

AUTOMATIC GAIN CONTROL
A process by which gain is automatically adjusted as a function of input or other specified parameter.

AUTOMATIC IRIS LENS
A lens that automatically adjusts the amount of light reaching the imager.
Backlight Compensation
A feature that compensates for bright backgrounds so foreground objects aren't silhouetted.

BNC
Bayonet Nut Connection. Also known as several other names. A connector for coaxial cable that is used in video connections and RG58 connections. The connector has a bayonet-type shell with two small knobs on the female connector which lock into spiral slots in the male connector when twisted on. BNC connections are easily adapted to RCA style jacks and plugs.

BROADBAND
High speed transmission. Allows for a wide band of frequencies on a single link. Different channels or frequencies within the band can send information concurrently, allowing more information to be transmitted within a short period of time. This allows for access to voice, data, and video all at the same time. DSL and cable TV providers are considered suppliers of downstream broadband. In television system use, a device having a bandpass greater than the band of a single VHF television channel.

BANDWIDTH
The number of cycles per second (Hertz) expressing the difference between the lower and upper limiting frequencies of a frequency band; also, the width of a band of frequencies.

BAR TEST PATTERN
Special test pattern for adjusting color TV receivers or color encoders. The upper portion consists of vertical bars of saturated colors and white. The power horizontal bars have black and white areas and I and Q signals.

BLOOMING
The defocusing of regions of the picture where the brightness is at an excessive level, due to enlargement of spot size and halation of the fluorescent screen of the cathode-ray picture tube. In a camera, sensor element saturation and excess which causes widening of the spatial representation of a spot light source.

BRIGHTNESS
The attribute of visual perception in accordance with which an area appear to emit more of less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)

BURNED-IN-IMAGE
Also called burn. An image which persists in a fixed position in the output signal of a camera tube after the camera has been turned to a different scene or, on a monitor screen.

CCD
Charged Coupled Device. A sensor that collects light and turns it into an electrical signal. As compared to CMOS sensors, it has greater sensitivity to light, better tonal range, and less noise which provides superior quality. CCD will hold onto the high-end CCTV market for some time to come. For imaging devices, a self-scanning semiconductor array that utilizes MOS technology, surface storage, and information transfer by shift register techniques.

CCD Format
The active imaging area of a CCD sensor, measured corner to corner.

CCTV
Closed-Circuit Television

CMOS
Complementary Metal Oxide Semiconductor. A semiconductor fabrication technology that achieves low power dissipation. These types of devices are used in digital camera imaging sensors and consume less energy than other imaging devices, are inexpensive, but provide lower image quality compared to CCD sensors.

COAXIAL CABLE
The type of cable most commonly used to transmit video.

COMPRESSION TECHNIQUES
There are several standardized formats for compressing video data. First off, video data needs to be compressed due the enormous amount of data being collected to replicate visual detail and motion. Two fundamental concepts to realize when deciding which video compression technique best suits your needs includes storage consumption and video quality. The most common video compression formats are MJPEG, MPEG-2 (DVD standard), MPEG-4, and Wavelet.

C MOUNT
A television camera lens mount of the 16 mm format, 1 inch in diameter with 32 threads per inch.

CCTV
Common abbreviation for Closed-Circuit Television.

CHARGE-COUPLED DEVICE

COAXIAL CABLE
A particular type of cable capable of passing a wide range of frequencies with very low signal loss. Such a cable in its simplest form, consists of a hollow metallic shield with a single wire accurately placed along the center of the shield and isolated from the shield.

COLOR BURST
That portion of the composite color signal, comprising a few cycles of a sine wave of chrominance sub carrier frequency, which is used to establish a reference for demodulating the chrominance signal. Normally approximately 9 cycles of 3.579545 MHz.

COLOR SATURATION
The degree to which a color is free of white light.

COMPOSITE VIDEO SIGNAL
The combined picture signal, including vertical and horizontal blanking and synchronizing signals.

COMPRESSION
The reduction in gain at one level of a picture signal with respect to the gain at another level of the same signal.

CONTRAST
The range of light to dark values in a picture or the ratio between the maximum and minimum brightness values.

DDNS
Dynamic Domain Name System. Allows for a dynamic or constantly changing IP address to be assigned to a networked device while allowing the associated domain name for that device to remain unchanged. The device in many cases is a server that provides information to clients. While an IP address must be assigned to the server, an optional domain name can be used to identify the device.

DVMR
Digital Video Multiplexing Recorder. A recorder that gathers and compresses video in a digital format to be saved on a hard drive. A DVMR is much different than a DVR. The DVMR is actually a multiplexing recorder, recording each individual channel in full screen to allow the best possible playback quality. Do to the advances in digital imaging, DVRs and DVMRs have come a long way and are quickly replacing VHS systems.

DIGITAL RECORDING
Technology that enables images from a camera to be stored on a hard drive. A digital recorder provides clearer images than videotape and faster access to them.

dB
Basically, a measure of the power ratio of two signals. In system use, a measure of the voltage ratio of two signals, provided they are measured across a common impedance.

DECODER
The circuitry in a color TV receiver which transforms the detected color signals into a form suitable to operate the color tube.

DEPTH OF FIELD
The in-focus range of a lens or optical system. It is measured from the distance behind an object to the distance in front of the object when the viewing lens shows the object to be in focus.

DEPTH OF FOCUS
The range of sensor-to-lens distance for which the image formed by the lens is clearly focused.

DIGITAL SIGNAL PROCESSING
An algorithm within the camera that digitizes data (the image). Examples include automatic compensate for backlight interference, color balance variations and corrections related to aging of electrical components or lighting. Functions such as electronic pan and zoom, image annotation, compression of the video for network transmission, feature extraction and motion compensation can be easily and inexpensively added to the camera feature set.

DISTORTION
The deviation of the received signal waveform from that of the original transmitted waveform.

DYNAMIC RANGE
The difference between the maximum acceptable signal level and the minimum acceptable signal level.
Electronic Shutter
A camera feature that compensates for changes in light conditions, from bright sunlight to dim indoor lighting.

ETHERNET
A local area network protocol that operates at OSI layer 2. This protocol is responsible for host to host communication and provides a method of media access for multiple computers to share. In older applications, the shared medium is a coaxial cable (RG8 or RG58 equivalent). Today, we find most applications to utilize a unshielded twisted pair (UTP) cable for connections rather than coaxial. There are several revised additions to the original standard, each describing a method of sharing a single medium with multiple devices. Each standards also specifies the speed at which data can be transferred. For instance, the 10baseT Ethernet cable standard specifies 10Mbit/sec data transfer over twisted pair cable that will not allow a device to transmit and receive data simultaneously. 100baseTX (Fast Ethernet) allows data to be sent and receive simultaneously providing faster data transmission at 100Mbit/sec over twisted pair cable.

FIELD OF VIEW (FOV)
The image area produced by any camera and lens combination (See focal length) .

FOCAL LENGTH
The distance from the center of the lens to the point where it focuses light. The combination of focal length and CCD format determines a camera's field of view. The shorter the focal length, the wider the field of view.

FOOT -CANDLE
A unit of luminance, incident light, or illumination equal to 1 lumen per square foot. This is the luminance provided by a light source of one candle at a distance of 1 foot, hence the name.

FIELD
One of the two equal but vertically separated parts into which a television frame is divided in an interlaced system of scanning. A period of 1/60 second separates each field start time.

FIELD OF VIEW
The maximum angle of view that can be seen through a lens or optical instrument.

FOCAL LENGTH
Of a lens, the distance from the focal point to the principal point of the lens.

FOCAL PLANE
A plane (through the focal point) at right angles to the principal point of the lens.

FOCAL POINT
The point at which a lens or mirror will focus parallel incident radiation.

FRAME
The total area, occupied by the television picture, which is scanned while the picture signal is not blanked.

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.