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Glossary
A

AC Adapter

 

Alternating Current Adapter; when plugged to AC Power (usually 117VAC/60Hz in the United States) it produces 12VDC, 24VAC or others. "UL Listed" and "Regulated" recommended. It is also called Power Transformer.

12VDC
Most board cameras, mini cameras and about one third of the professional cameras work with 12V DC 100mA to 200mA for B/W cameras and 150mA to 300mA for color ones.

24VAC

About two thirds of the professional cameras work with 24VAC, 20VA to 40VA. The cameras usually have screw type connections and you don't need to worry about the polarity. This power is usually supplied with AC Adapter and you need to prepare separate power cable for the connection. Unlike 12VDC, this power can be transmitted to a long distance up to 450ft and is proper for the cameras that are to be installed out-door or when you don't have the power outlet near the camera.

   
 

AC Power

 

Alternating Current Power. In the United States, the standard AC Power is single-phase 117VAC/60Hz and is provided from power outlets in the house. 24V AC power can be produced from an AC Adapter.

   
  AGC
 

The video signal is amplified at low light levels by an automatic gain control circuit. Unfortunately noise is also amplified. In some cameras the gain level can be controlled manually. (MGC = manual gain control).

 
 

Analogue

 

Continuously variable numerical values such as voltage, current, etc. (The CCD camera produces analogue video signals.)

   
 

Angle of View

 

The scene angle that a video camera lens can show on the monitor, like Diagonal Angle, Horizontal Angle and Vertical Angle, usually described in degree.

<More details>
Focal Length (FL) is the distance from the center of a lens to the focal point (CCD sensor chip). FL, as well as the CCD chip's format, is the major factor to determine the angle of view of a lens. For example, a 6.0mm FL lens on 1/3" sensor format has 56.8 degree of diagonal angle of view and a 5.0mm FL lens on 1/3" sensor format has 66.9 degree. But, the same 6.0mm FL lens can see 75.5 degree on 1/2" sensor format. The angle of view also varies a little depending on the Manufacturer of the lens.

For 1/3" CCD chip camera, the following formula is a simple way to determine the focal length of a lens needed.

(Distance to subject / Width of subject) x 4.5mm = Focal Length.

For example, if you want to watch a subject of 5.5ft width at 10ft distance with a 1/3" CCD camera, you will need a 8.0mm FL lens. That is, 10ft / 5.5ft x 4.5mm = 8.18mm. A 8.0mm FL lens mounted on 1/3" CCD camera will cover the subject you want to watch.

 
B

Bandwidth

 

The number of hertz (cycles per second) showing the difference between the lower and upper frequencies of a frequency band video uses higher frequency than audio, thus requires a wider bandwidth.

 
  BLC
 

Adjust the electrical shutter according to special area of measuring light. The exposal value will be normally in the measuring area.

   
C

C-MOS

 

Complementary Metal -Oxide Semiconductor. A video image sensor chip that produces much lower quality picture than CCD chip.

   
 

Camera Sensor

 

Video image sensor
CCD or C-MOS chip

<More details>
CCD (charge coupled device) consists of several hundred thousand individual picture elements (pixels) on a tiny 1/2", 1/3", or 1/4" chip. Each pixel responds to light falling on it by storing a tiny charge of electricity. The pixels are arranged on a precise grid, with vertical and horizontal transfer registers carrying the signals to the camera's video processing circuitry. This transfer of signals occurs sixty times per second. The 1/3" CCD chip is the most widely used sensor format these days; its size is 5.5mm (diagonal), 4.4mm (horizontal) and 3.3mm (vertical). The 1/4" sensor format, recently being used in color cameras, is 4mm (diagonal), 3.2mm (horizontal) and 2.4mm (vertical).

C-MOS (Complementary - Metal Oxide Semiconductor) chip, also a video image sensor, produces much lower quality picture than CCD chip

   
 

CCD

 

Charge Coupled Device. A video image sensor chip
CCD (charge coupled device) consists of several hundred thousand individual picture elements (pixels) on a tiny 1/2", 1/3", or 1/4" chip. Each pixel responds to light falling on it by storing a tiny charge of electricity. The pixels are arranged on a precise grid, with vertical and horizontal transfer registers carrying the signals to the camera's video processing circuitry. This transfer of signals occurs sixty times per second. The 1/3" CCD chip is the most widely used sensor format these days; its size is 5.5mm (diagonal), 4.4mm (horizontal) and 3.3mm (vertical). The 1/4" sensor format, recently being used in color cameras, is 4mm (diagonal), 3.2mm (horizontal) and 2.4mm (vertical).

 
 

CCTV

 

Closed Circuit Television
It does not broadcast TV signals but transmits them over a closed circuit through electrically conducting cable or wireless transmitter and receiver.

<More details>

CCTV, Closed Circuit Television, is a TV system that does not broadcast TV signals to public but transmits them over to limited monitor(s). CCTV system usually utilizes CCD video cameras (to produce the video), cable or wireless transmitters / receivers or Internet (to transmit the video), and monitors (to see the video). CCTV system is not only applied to serve the security and surveillance purpose but also to other fields like laboratory in schools or in private companies, even to production lines in factories. As the application of CCTV system increases, the CCTV industry has developed various of CCTV equipment such as time lapse VCRs, combiners, infrared illuminators, pan / tilt, etc. The most recent development is web camera server that uses the Internet for remote surveillance.

   
 

Camera

 

A part of the CCTV system that captures the video pictures.

   
 

Monitor

 

A part of the CCTV system that receives the video pictures from a camera and displays them.

<More details>
B/W Monitor and Color Monitor
In the past, 9 to 12 inch (diagonal) B/W monitors were widely used in the field. These days, many people are looking for 14 inches for color monitor and 17 inches for B/W. As the color monitor needs 3 different color dots to produce one pixel of information on the monitor, it usually has lower resolution than B/W monitor.

Single Monitor, Quad Monitor and 4-CH. Monitor
Single Monitor is usually professional monitor with one video input of BNC jack. Quad splitter, video switcher or multiplexer can be connected to single monitor to combine multiple cameras. Quad monitor has built-in quad splitter and usually has 4 DIN jacks for video inputs. 4-CH Monitor has built-in 4 channel video switcher and usually has 4 DIN jacks for video inputs. Quad Monitor or 4-CH. Monitor is usually a part of packaged observation system and is not compatible with other Manufacturerr's camera or cable.   
    

 
 

CRT

 

Cathode Ray Tube
The vacuum tube part of a monitor or television.

 
D

DC Power

 

Direct Current Power; can be derived from an AC adapter or from a battery. Among DC voltages of 6, 9, 12, 24, and 28, 12VDC is most common in the CCTV industry.

<12VDC>

Most board cameras, mini cameras and about one third of the professional cameras work with 12V DC, 100mA to 200mA for B/W cameras and 150mA to 300mA for color ones. These cameras usually have DC jacks to accept DC power plugs. You should be careful about the polarity (positive and negative) for this power source. 12V DC power can be supplied with AC Adapter or battery pack. You may even use a "power cord" plugged to the cigarette lighter in a car.

   
 

DVR

 

Digital Video Recorder records video pictures digitally. DVR, Digital Video Recorder, records video pictures digitally on a hard disk drive(HDD). This HDD, usually built-in, has capacity of 20 Gb, 30 Gb or 60Gb to store the records. You can program the picture resolution and recording time according to the application; real-time or time-lapse recording also available. Overwriting the oldest pictures is programmable. Event alarm recording that records, only when a movement is captured within the image frame, is easier to program and more reliable than the Time Lapse VCR's alarm recording function. You just assign dots over the screen where you want to detect the movement. As DVR records digitally, the image quality remains the same regardless of how many times the images are stored or rerecorded. And, you can select images quickly by using time/date or alarm search, or just browsing through.

   
E Electronic Shutter
 

Electronic Shutter, one of the major features of CCD camera, is not really a moving shutter, but a clever piece of signal processing.

Under low light conditions, the CCD is allowed to gather signal at the electronic shutter speed of full 1/60th of a second.

Under brighter lighting conditions, the video processing chip automatically responds by reading the CCD and then immediately "early purging" it, resulting in precise control over the video level. Even at a shutter speed of 1/100,000th of a second, the CCD camera is still delivering 60 images per second, but each image is gathered over a much shorter period of time. The end result is a fantastic picture, with no fading, no adjustments, and best of all, unbelievable reliability.

 
F

FCC

 

Federal Communications Commission; controls also wireless camera system as one of the commercial broadcasting systems.

   
  F/f
 

Focal Length = (Distance to subject / Width of subject) x 4.5mm

For example, if you want to watch a subject of 5.5ft width at 10ft distance with a 1/3" CCD camera, you will need a 8.0mm FL lens. That is, 10ft / 5.5ft x 4.5mm = 8.18mm . A 8.0mm FL lens mounted on 1/3" CCD camera will cover the subject you want to watch.

Optical or lens speed. Smaller f-number means faster lens.
Optical Speed is about how fast a lens collects lights and is defined by the f-number like f/1.2, f/2.0, etc. This speed is determined by the Focal Length (FL) and the Diameter (D) of a lens; f-number = FL/D.
In conclusion, the lower the f-number, the more lights reaching the camera sensor and the better the video picture. The f-numbers are usually marked at the iris rings of lenses.

   
G Gamma value
 

It is a corrective value to take in account the fact that picture display re-produced by monitor is not linear. Generally it is set at 0.45; however with some industrial applications it is preferably set to 1. By changing gamma value the contrast of image is also changed.

   
I

Infrared Light

 

Invisible light beyond the 750 nanometers (red end of the visible lights)

   
J

JPEG

 

Joint Photographic Experts Group. A graphic image file or a image compression algorithm.

 

 

K

KB

 

Kilobyte

 

 

Kbps

 

Kilobits per second
A measure of bandwidth

   
L

LED

 

Light Emitting Diode.

   
M

MB

 

Megabyte

 

 

Mbps

 

Megabits per second
A measure of bandwidth

   
 

MOS

 

Metal-oxide Semiconductor. One of the video image chips like CCD, but it produces lower quality video.

   
 

MPEG

 

Moving Picture Experts Group.
A standard for a digital video & audio compression

 

 

 

Multiplexer

 

Combines two or more video/audio signals into one channel. Usually accepts 10 or 16 video inputs and displays them in various formats.

   
N

NTSC

 

National Television System Committee; formulates standards for American color television system. NTSC system has 525 horizontal scan lines and 30 frames per second.

   
O ODM
  Original Design Manufacturer.
   
  OEM
  Original Equipment Manufacturer.
One that produces complex equipment (as a CCTV system) from components usually bought from other Manufacturers.
   
P

PAL

 

Phase Alternating Line system.
A color television system used in Europe, Australia, parts of Africa and the Middle East
It has 625 horizontal scan lines and 25 frames per second.

 
 

Picture Element (Pixel)

 

Photo Sensor site in the image sensor like CCD chip; converts the input light image to an electronic signal.

<More details>
These are the individual photo-diodes that form the sensor matrix. Their number varies according to sensor type and is strictly related to camera resolution. The number of pixels is usually given in two different forms:

a) Total pixels
It is the total number of pixels on the CCD faceplate; however some of them are not usable.

b) Active pixels
It is the actual number of active pixels; this value is always a lower figure than total pixel, but is the only reliable value.

   
 

Pixel

 

Picture Element. Photo Sensor site in the image sensor like CCD chip; converts the input light image to an electronic signal.

   
R

RCA

 

The Radio Corporation of America; conveniently used to describe phono jack and plug, one of the audio/video connectors.

   
 

Resolution

 

Expressed by TV lines or pixels, it indicates the quality level of video images.

<Camera Resolution>
The industry of CCD video camera sensor uses pixels (picture elements) as its quality parameter. Medium resolution of B/W camera in EIA system is 510 horizontal pixels by 492 vertical pixels and is equivalent to 380 TV lines. High resolution is 768(H) x 492(V) pixels and equivalent to 570 TV lines. Color camera's medium resolution means 330TV lines and high resolution needs more than 460 TV lines.

<Monitor Resolution>
The monitors in NTSC system have 525 vertical scanning lines regardless of their size. The horizontal 700 TV lines of B/W monitors represents medium level and more than 900 TV lines means high resolution in EIA system. The color monitor's horizontal resolution of 300 TV lines means medium quality and that of more than 450 TV lines means high resolution.

 
S

Sensitivity

 

Sensitivity can be quoted in two different ways.
a) Usable picture
Sometimes this is called minimum illumination. This gives merely an indication of minimum light level at which the camera starts providing an output video signal.
b) Full video
This is the real value to be taken into consideration as it gives the lowest light value at which camera supplies a full output video signal "1V peak to peak". This value is important for the whole CCTV system because many devices need a full signal to operate properly.

Sensitivity can be measured:
a) At the faceplate
In this way, it measures the camera performance when light falls directly on the sensor faceplate. Although this is a technically correct figure, it never actually happens, because to get a real picture you need a lens, which reduces in some ways the light amount falling on the faceplate.
b) At the lens
This is a more effective value of the actual sensitivity of the camera + lens system. Obviously the lower the F-No., the better result you get.

<For instance>
A camera having a value of 0.1 Lux (full video) with f1.4 lens has a higher sensitivity than a camera showing the same value of 0.1Lux with f1.2 lens. By using f1.2 lens with the 1st camera its sensitivity would be possibly around 0.08 Lux. Another value to be taken into consideration is the scene reflectance (which is the light amount, in percentage, reflected by the scene).
The higher is the reflectance value, the higher is the light amount available to the camera faceplate. Usually the reflectance is something between 65% and 90%.

<For Instance>
A camera having a sensitivity of 0.1Lux (full video) with a f1.2 lens with a reflectance value of 70% is more sensitive than a camera having the same sensitivity (full video) with the same lens but at 90%.
The sensitivity value is normally specified in ‘Lux'. However some American Manufacturers give this value in foot-candle. 1Lux = 10fc.

   
  S/N ratio signal/noise ratio
 

It is a measure showing the amount of interference caused by noise. Its value is important especially at low light levels. The higher its value, the better will be the picture quality at low light levels.

T TV SYSTEM
  1.CCIR/EIA is for B/W system
 

(1)CCIR is made the technical recommendation for the European 625 line standard for video signals.

 

(2)EIA is American standard for B/W camera system.

  2.PAL/NTSC is for color system.
 

PAL is a color television system, which is used in Europe, Australia , parts of Africa and the Middle East . It has 625 horizontal scan lines and 25 frames per second. (Frame: A whole video image; is composed of two interlaced fields. A CCD chip produces 30 frames per second at NTSC system and 25 frames at PAL. )

 

NTSC formulates standards for American color television system. NTSC system has 525 horizontal scan lines and 30 frames per second.

 
V

Videocassette Recorder (VCR)

  A device that accepts signals from a video camera / microphone and records
video / audio on magnetic tape in a cassette. The VCR can play back recorded
video / audio on a television set or monitor.
 

 


 
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