AC Adapter

   Alternating Current Adapter; when plugged to AC Power it produces 12VDC, 24VAC or others. It is also called Power Transformer.

 

12VDC

12 volt Direct current voltage. Most board cameras, mini cameras work with 12V DC.

 

AC Power

  Alternating Current Power.

   

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.

 

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-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

 

  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.

   

  Camera

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

 

  CRT

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

 

  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.

   

  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.

  

  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.

 

  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

 

  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.

 

Infrared Light

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

 

JPEG

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

 

KB

   Kilobyte

 

   Kbps

   Kilobits per second, A measure of bandwidth

  

LED

   Light Emitting Diode

 

  MB

  Megabyte

 

  Mbps

  Megabits per second, A measure of bandwidth

 

  Monitor

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

 

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 Manufacturer's camera or cable.       

   

  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.

 

  NTSC

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

 

  ODM

  Original Design Manufacturer.

   

  OEM

  Original Equipment Manufacturer.

One that produces complex equipment (as a CCTV system) from components usually bought from other Manufacturers.

   

  PAL

  Phase Alternating Line system.

A color television system used in Europe, Australia, parts of Africa and theMiddle East

It has 625 horizontal scan lines and 25 frames per second.

 

  Pixel

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

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.

 

  RCA

  The Radio Corporation ofAmerica; 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.

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.

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.

 

  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.

 

  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.

 

  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 theMiddle 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.

 

  Video Cassette 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.