Results 1 to 1 of 1

Thread: CCTV Glossary

  1. #1
    Senior Member
    intelliGEORGE's Avatar
    Join Date
    Jan 2008
    Location
    Sydney, AUSTRALIA
    Age
    43
    Posts
    4,106
    Thanks
    884
    Thanked 1,484 Times in 691 Posts
    Rep Power
    478
    Reputation
    7236

    Default CCTV Glossary

    Auto Iris

    A feature in many lenses that allows the lens to compensate for changing lighting conditions. Under bright lighting conditions it allows the Iris to be closed, and then opened in lower light situations. It's very good at handling gradual lighting changes and less effective at handling rapid lighting changes.

    AGC (Automatic Gain Control)

    This feature tries to keep the signal strength even. This can boost weak signals (low light conditions) and reduce strong signals (overly bright light) as well as improve general picture quality.

    ALC (Automatic Level Control)

    This allows for users to manually adjust if the camera should see more details in brighter areas or darker areas.

    AWB (Auto White Balance)

    Auto White Balance allows a camera to correct for different types of lighting. Florescence lighting can cast a blue-ish tinge compared to natural lighting. AWB attempts to correct for this. On some cameras it may need to be set manually by holding the camera next to a white piece of paper.

    ATW (Auto Tracing White Balance)

    A mode intended for more dynamic lighting conditions then AWB.

    Backfocus

    The final distance between the imager and the back glass of the lens.

    Balun (Balanced Unbalance)

    This converts a balanced (twisted pair) to unbalanced (coax) connector. It's used most often with twisted pair or Cat5 wire.

    BLC (Back Light Compensation)

    The feature opens up the Iris a little more, attempting to allow more light in from foreground subjects so that bright light sources behind an object don't cause a "blooming" effect.

    BNC

    Connector type used in CCTV. Fairly easy to twist on and off, but resistant to being yanked off.

    C/CS Mount Lens

    This refers to the distance from the lens to the imager (CCD or CMOS chip). Most modern cameras support CS lens and may include a spacer ring for mounting C style lens.

    CCD (Charged Couple Device)

    One of two major technologies for converting light into an electric signal. CCD chips are separated from the devices that convert its electrical signal into NTSC/PAL signals. This reduces some of the interference from other electronics. CCD's are a little more expensive but generally give a better image then their CMOS counterparts.

    CCTV (Closed Circuit Television)

    A reference to the time in which the video signal only fed to one source.

    Co-ax (Coaxial Cable)

    A shielded cable with copper running down the center. For CCTV work, RG-59 Copper shielded is the kind of cable used.

    dB (Decibel)

    A measurement of signal strength. It is measured logarithmically. 6dB difference is twice the signal strength. The higher the dB rating, the better the image quality will be.

    DD Lens: (Direct Drive)

    A lens that requires a DC signal from the camera to close the lens.

    Depth of Field

    This is the distance at which the camera is in good focus. This distance is a factor of the lens used. Varifocal lens allow for the user to set this distance. Generally this should be set in dim light to get the best balance between day and night. Use of a Neutral Density filter can make this easier.

    DVR (Digital Video Recorder)

    A device for recording video signals to either a hard drive or some kind of optical media. (Sometimes called a CCTV DVR or DVR.)

    EI (Electronic Iris)

    This simulates auto-iris through the use of controlling contrast and brightness.

    Field of View

    A measurement of how wide and high of an image will be. Measured in degrees, but when mixed with a depth of field measurement it can be displayed as feet or meters.

    FPS (Frames Per Second)

    This is the number of frames, or images, taken each second. TV is 25 frames per second. Sometimes referred to fields per second. TV would be 50 fields per second.

    F- Stop

    A ratio of focal length to lens diameter. The lower the number, the more light will strike the CCD.

    Ground Loop

    An alternating current (AC) that can be produced in a cable. This is usually caused by parts of the system being fed from different electrical sources resulting in different earth potentials at each end of the signal path. This results in interference of the video pictures in the form of a black shadow bar across the screen or as a tearing effect in the top comer of a picture.

    Lux

    A measurement of how much light is striking a surface.
    Approximate Lux Description of Situation
    < 0.001 Starlight overcast night
    0.001 - 0.01 Starlight - clear night
    0.01 - 0.1 Overcast Night
    0.1 - 1 Moonlight
    1 - 100 Dusk / Twilight
    100 - 10,000 Overcast Day
    10,000 - 1,000,000 Bright Sunlight

    Multiplexer

    A device that takes multiple camera inputs and outputs them as one stream.

    NVR (Network Video Recorder)

    A DVR that pulls a signal from cameras across a network.

    Neutral Density Filter

    A piece of glass or plastic that reduces all types of light evenly. It's used to force an iris open to allow for good focus at night when doing the original focus of the camera.

    PTZ (Pan, Tilt, Zoom)

    A camera with the ability to be moved by the operator. Popular among Casinos, less useful for applications without 24 hour monitoring.

    TVL (Television Lines)

    A measurement of resolution. It measures the number of horizontal lines.

    Varifocal Lens

    A lens that allows the user to change its focal distance. Usually shown like this. 8-80mm lens. This means the lens can be adjusted to be any focal distance between 8mm to 80mm.

  2. The Following User Says Thank You to intelliGEORGE For This Useful Post:

    mobsta (13-06-09)



Look Here ->

Similar Threads

  1. Dumb Criminals Caught on CCTV
    By intelliGEORGE in forum CCTV
    Replies: 25
    Last Post: 01-02-11, 08:12 PM
  2. Understanding Ground Loops in CCTV
    By intelliGEORGE in forum CCTV
    Replies: 13
    Last Post: 09-06-09, 10:17 AM
  3. Useful CCTV tools
    By intelliGEORGE in forum CCTV
    Replies: 12
    Last Post: 31-01-08, 05:11 PM
  4. CCTV Basics - For the Youngsters
    By intelliGEORGE in forum CCTV
    Replies: 4
    Last Post: 29-01-08, 05:58 PM
  5. Right Lens For CCTV Applications
    By intelliGEORGE in forum CCTV
    Replies: 0
    Last Post: 16-01-08, 09:12 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •