Technical Terms                                                                                    

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  Technical Terms:

  • AC refers to alternating current electricity. Many CCTV products use 24 volts AC, for which a separate power transformer is required.

  • AC/DC refers to changing between alternating current (AC) and direct current (DC). To switch from AC power to DC a transformer can easily be used to regulate the current. Power inverters convert DC current to AC current.

  • Amps (A) are used to measure electrical current consumption. 1 amp (A) = 1000 milliamps(mA).

  • Analog indicates a particular electrical signal which conveys electronic data (i.e. a video signal or audio signal). Information carried over an analog signal is a representation of data by continuously varying quantities. An analog electrical signal has a different value of volts or amperes for electrical representation of the original excitement (light, sound, etc.) within a dynamic range specific to the analog device.

  • Automatic Gain Control (AGC) refers to a circuit within the camera which regulates image brightness levels for optimum performance and highest video quality.

  • Automatic Light Control (ALC) indicates the image sensor's ability to automatically adjust in diverse lighting conditions to yield the most vivid video image possible.

  • Auto-Iris Lens is a lens with a built-in method of automatically controlling the lens aperture for the best video quality under diverse and changing lighting conditions. Auto-iris lenses can be especially helpful under very low light and bright direct forward light.

  • BNC is the type of connector plug commonly found on CCTV devices for video and audio input / output connections. BNC plugs are easily adapted to standard consumer RCA connectors using a simple one-piece plug adapter. Required for use with plug and play cable.

  • Bandwidth indicates the complete range of frequencies over which a circuit or electronic system can function with minimal signal loss. In effect, bandwidth indicates the amount of information and its complexity which can be carried over a signal. More complex information requires more bandwidth for an effective signal.

  • Back Lighting Compensation (BLC) indicates the image sensor's ability to automatically adjust in conditions where lighting is from behind the camera to deliver the sharpest and highest quality video image possible.

  • Black & White Camera is typically referred to as black and white because video image produced is in shades of gray. Only black and white CCD cameras have the ability to utilize IR infrared lighting. Even without infrared lighting, a black & white camera will generally perform better in low light conditions and deliver a crisp image.

  • Bullet Camera refers to a camera with a cylindrical shape using an inline video imaging chip rather than a board design.

  • CCD (Charge Coupled Device) is one of the two main types of image sensors used in digital cameras. When a picture is taken, the CCD is struck by light coming through the camera’s lens. Each of the thousands or millions of tiny pixels that make up the CCD convert this light into electrons. The number of electrons, usually described as the pixel’s accumulated charge, is measured, then converted to a digital value. This last step occurs outside the CCD, in a camera component called an analog-to-digital converter.

  • CMOS (Complementary Metal-Oxide Semiconductor) is one of the two main types of image sensors used in digital cameras. Its basic function is the same as that of a CCD. CMOS sensors are currently found in only a handful of digital cameras.

  • Coaxial Cable is the most common types of cable used for transmitting a video signal through copper wire. This type of wiring has a coaxial cross-section where an outer shielding protects the actual interior signal conductor from electromagnetic interference. In the CCTV industry, the term "coax" usually refers to RG-59 cable with BNC-type plug ends.

  • Color Cameras produce video images bearing the entire visible spectrum of colors. The color in pictures appear vivid, crisp, and distinguished on monitoring and playback of video.

  • DC refers to direct current electricity. Typically 12 volts DC, which can easily be adapted from standard AC wall outlets using a regulated AC/DC transformer. Unlike AC current, DC flows in only one direction within a circuit and therefore requires the correct +/- polarity.

  • Digital Video Recorder (DVR) device is capable of accepting one or more video (and sometimes audio) input signals for recording onto digital storage media. A DVR is basically a computer specifically designed to gather and compress video into a digital video format for storage on a hard disk drive or other form of digital media. Some DVRs offer built-in motion detection recording and can be viewed remotely and played back over the internet. Some models may easily be backed up onto external media, such as built in cd burners.

  • DVR Card is a device for installation in a home PC computer which converts that PC into a DVR digital video recorder by gathering video and compressing it into digital information onto a computer's hard disk drive.

  • Electronic Shutter is a feature that automatically changes the speed at which light is captured in fields of video by the CCD image sensor. Automatic electronic shutter determines the amount of light available and helps deliver the best quality video by dynamically adjusting for the current lighting conditions by toning down light levels in very bright situations and boosting brightness in low lighting situations.

  • Ethernet/Modem indicates a network communication device for computer-type devices. Most DVR video recorders come standard with built-in Ethernet LAN connection (with 'RJ-45' plug) to enable remote internet viewing and/or network operation.

  • Focal Length indicates the distance between the optical center of a lens and a video camera's image sensor device. For practical purposes, Len's focal length refers to a camera's angle of view. Lenses with a higher focal length number have more narrow, telephoto fields of view (6-12mm). A very low number focal length indicates a very wide field of view (2.5-3.6mm).

  • Fixed Lens has one set focal length with a specific field of view which cannot be changed. Any camera without Varifocal option has a fixed focus lens. Meaning, the user cannot manipulate the field of view, everything in the picture beyond a few inches will be clear and in focus. Objects simply get smaller as they move further away from the camera.

  • Frames per Second (FPS) describes the number of full video frames displayed or recorded within one second. True Realtime video consists of 30 frames / sec. A complete frame of video is compiled of two separate images (or fields), so the number of fields in one second is always twice the number of frames per second.

  • FPS Display Rate indicates the number of frames per second a VCR or DVR recorder will display on a monitor for simultaneous viewing. The rate at which each camera is displayed is often NOT the same as the number of frames per second the recorder captures for playback.

  • FPS Record Rate describes exactly how many frames per second a video recorder can actually capture. Analog recorders like VCRs can easily record in Realtime (30 frames / sec. or time-lapse (fewer than 30 frames / sec.).

  • Hard Disk Drive (HDD) is a magnetic media storage device for recording digital information (like that used by computers or digital DVR video recorders).

  • HDD Capacity indicates the amount of information which can be stored on hard disk drive. This figure is measured in bytes: 1 GB = 1016 MB = 1032256 KB = 1048772000 bytes.

  • IR Infra Red Light is a frequency of light which is lower than the human eye's visible spectrum (in the range of 850 ~ 950 nanometers). Color cameras CANNOT use infrared light whatsoever. However, this special band of light CAN be detected by most black and white CCD camera. Therefore, a black and white video camera in combination with infra red lighting can see in pitch dark conditions. An infra red light source appears just the same as any visible light source on a black and white camera image.

  • JPEG is a standard for compressing image data. It is not a file format, it’s a compression method that is used within a file format. Some quality is lost in achieving JPEG’s high compression rates. Usually, if a high-quality, low-compression JPEG setting is chosen on a digital camera, the loss of quality is not detectable to the eye.

  • LCD (Liquid Crystal Display) is a low-power monitor often used on the top and/or rear of a digital camera to display settings or the photo itself.

  • Lens is an optical device which bends light, focusing it on onto an image sensor to create a distinct, visible image. All video cameras need lenses in order to obtain a clear picture. Lenses come in a variety of focal lengths. The focal length of a lens, in combination with the size of the imager, will determine its field of view.

  • Low Light (or low lux) Sensitivity refers to a camera's performance under low lighting conditions. Sony 1/3 " Ex-View and SuperHAD CCD chip sets have the best low light performance.

  • Lux is a measure of light in terms of candle power (measured in foot candles). Lux is often given as a technical specification for cameras to describe the lowest level of light required for the camera to produce any kind of an image. However, this number lists the absolute lowest level of light needed to move ANY of the image sensor's pixels. A lower "lux" rating indicates performance in darker conditions.

  • Megabyte (MB) is a measurement of data storage equal to 1024 kilobytes (KB).

  • Milliamps (mA) is a measure of electrical current power consumption. 1 amp (A) = 1000 milliamps (mA).

  • Multiplexer is a video switching device that accepts video input from multiple cameras and converts them to all display on one monitor and / or video recorder (similar to a quad video processor) However, a multiplexer is far more advanced. Video multiplexers use time division multiplexing, meaning that a full frame of video from each camera is recorded every few seconds. While multiplexed video does not achieve true Realtime display or recording (there is a slight drag to the images on playback), multiplexers do offer the capability to change between a view of several cameras and a solid close up view of only a single camera's view on playback of recorded video. When using multiple cameras, quads and multiplexers help to cut down on the amount of additional equipment needed for a dedicated surveillance system.

  • Pan/Tilt/Zoom (PTZ) indicates equipment with the ability to pan, tilt and zoom, usually controlled by remote. Much of PTZ equipment is completely integrated, meaning there is only one controller necessary to operate all three features.

  • Quad Processor is a video switching device that accepts video input from four cameras and converts them to all display on one monitor and / or video recorder. When using multiple cameras, quads and multiplexers help to cut down on the amount of additional equipment needed for a dedicated surveillance system.

  • RCA is a common connector plug for standard consumer video and audio equipment. RCA jacks are found on all VCRs. In most cases, RCA jacks are color coded yellow, white, and red. BNC plugs are easily adapted to standard consumer RCA connectors using a simple one-piece plug adapter.

  • Remote Playback is a feature of many DVRs. This allows users to play back recorded video over the internet from virtually any computer in the world.

  • Remote Viewing is a feature of many DVRs. This allows users to monitor CCTV cameras over the internet from virtually any computer in the world.

  • Resolution (TV lines) refers to the maximum number of vertical lines /pixel elements (horizontal resolution) a video camera is capable of displaying on a monitor or registering with a video recording device. Horizontal resolution indicates the number of pixel elements placed horizontally across each scanning line of resolution (vertical resolution). Horizontal resolution varies based on the abilities of each different camera and each different monitor. The number of TV lines of horizontal resolution is generally considered a measure of a camera's level of detail and sharpness in video quality.

  • Shutter Speed is a measurement of how long its shutter remains open as the picture is taken. The slower the shutter speed, the longer the exposure time. When the shutter speed is set to 1/125 or simply 125, this means that the shutter will be open for exactly 1/125th of one second. The shutter speed and aperture together control the total amount of light reaching the sensor. Some digital cameras have a shutter priority mode that allows you to set the shutter speed to your liking.

  • Time-lapse refers to recording one still video image frame at fewer than 30 frames per second. The speed of this recording can usually be adjusted. Time-lapse video is therefore slower than Realtime recording and has a drag when the video is played back. One advantage of time-lapse recording is the ability to increase maximum recording time so longer periods of time can be captured on a video tape or digital hard disk drive. However, a major disadvantage of time-lapse recording is missing many frames of video and missing much of what happens during a given period of time. There is no way to recover these missed frames on playback. For the ultimate in surveillance, Realtime video recorders deliver the most complete and accurate video information of what occurred.

  • VCR stands for video cassette recorder. This is an analog device capable of accepting a video (and usually audio) input signal for recording.

  • Varifocal Lens allows the user / installer to manually adjust the camera's field of view. Varifocal lenses can therefore be changed to provide wider viewing angles or narrower telephoto viewing angles. Because of their adjustability, Varifocal lenses are great when a camera will serve more than one purpose or to ensure proper focus without first determining an exact fixed lens focal length. Varifocal lenses are also typically referred to as zoom lenses.

  • Weatherproof Equipment has been specifically designed for safe use in most outdoor weather conditions. However, weatherproof equipment should not be considered waterproof because it is not intended to be placed in direct weather. At the same time, there may also be extreme weather conditions which even standard weatherproof video equipment cannot function properly. Heating or cooling fans are encouraged for these types of conditions. Weatherproof cameras must be placed under some type of eave or covering with or without a housing.

  • Zero Lux Operation refers to video imaging in pitch black (0.0 lux) lighting conditions. Black/White cameras can use IR lighting to yield crisp and distinguishable video images when absolutely no visible light is available.

  • Iris Lenses, Manual are perfect for common interior surroundings with constant light, such as interior of shopping centers, schools, libraries, and offices. Manual Iris Lenses are ideal for such locations, because the iris setting of the lens only needs to be set once during the installation.

  • Iris Lenses, Auto are perfect for locations, where light is constantly changing, such as outside parking lot, and building entrances. Auto Iris Lenses are powered through cameras power supply. The iris for these lenses automatically opens and closes according to the changes of the light conditions. If the light level is low, the lens iris opens up to allow enough light for optimum picture quality, and when the light level is high, it closes the iris so that incoming light does not overwhelm the camera and blur out the picture.