A/V (audio/visual) hard disks are optimized for write operations and have a higher MTBF (mean time between failure) than a standard PC hard disk. A DVR is constantly writing to the disk, in contrast to a PC which is more often reading from the disk. For installation in DVRs, PolarisUSA always recommends using A/V drives for greater reliability and performance.
Auto Gain Control is a feature that allows the camera to automatically adjust the overall gain of an image to help normalize the output levels. As the lighting changes, the camera will attempt to keep the overall image at a consistent level of brightness.
AHD is an acronym for Analog High Definition
ALC is an acronym for Automatic Light Control See also 'HLC'.
Adaptive Tone Reproduction function provides gradation compensation to improve the contrast of subjects whose gradation has been lost in cases where both low-luminance areas and high luminance areas exist in the same picture.
Automatic Tracking White Balance is a feature that continually tracks and adjusts the white balance, making it suitable for use in cameras in which the image content and lighting are subject to changes.
Auto Iris (AI)
In an Auto Iris configuration, the camera maintains a fixed shutter speed and varies the size of the lens aperture in accordance with lighting conditions. See also 'Manual Iris'.
Auto White Balance is a feature in cameras that is used for color correction. Shifting lighting conditions can sometimes cause improper video coloration, and AWB attempts to correct this.
Backlight compensation (BLC) is a feature in cameras used for scenes with too much light behind a subject, which can cause silhouetting. BLC will automatically adjust the contrast to help bring out the detail that was lost.
Central Management Software
Central Management Software (CMS) is software designed to manage multiple unique IP video servers (whether a camera or DVR) from a single interface. For example, CMS would allow you view/control two separate network DVRs housed in two different locations within the same software interface.
Dead Pixel Compensation
Dead Pixel Compensation (DPC) is used to detect and repair dead or hot pixels. The camera lens must be totally covered before starting this process. This will compensate for any pixels that are no longer changing color.
See 'Dead Pixel Compensation'...
H.264 is an addition to the MPEG4 family of audio/video formats. It supercedes MPEG4 part 2 which is commonly used in DVRs, and offers significantly greater compression than JPEG2000 and MPEG4 part 2 with only slight degradation of quality. See also 'MPEG4' and 'JPEG2000'.
H.265, otherwise known as HEVC (High Efficiency Video Coding), is the most recent video compression standard as a successor to H.264 with both higher precision and efficiency, but an increased demand of computational power See also 'H.264'.
HLC is an acronym for Headlight Compensation See also 'ALC'.
Highlight Suppressing Back Light Compensation masks off areas that are above a certain brightness. This is very useful for seeing reflective license plates or bright areas that may blind the camera.
IP stands for Ingress Protection
The ratings first digit relates to the Ingress Protection against dust:
6-Totally protected against dust
The second digit relates to the Ingress Protection against water:
6-Protected against temporary flooding of water, e.g. for use on ship decks - limited ingress permitted
7-Protected against the effect of immersion between 15cm and 1m
8-Protects against long periods of immersion under pressure
JPEG2000 is an audio/video format developed by the Joint Photographic Experts Group. As it relates to DVRs, it is one of the major compression algorithms used, and offers a higher image quality than most other formats, but at the expense of bandwidth/recording space. See also 'H.264' and 'MPEG4'.
Looping Video is a feature on DVRs and monitors that simply means that the video input also has a pass-through video output. On monitors it is used to chain multiple monitors together. On DVRs it allows you to hookup individual spot monitors for each camera.
Lux is the SI unit of illuminance, and in cameras is used to measure the minimum lighting required for the camera to register a usable image. A well-lit office area is about 400 lux.
In a manual iris configuration, the lens aperture is fixed and the camera adjusts its shutter speed in accordance with lighting conditions. See also 'auto iris'.
A Megapixel is a million pixels. So a 4MP camera will bring you 4 million pixels of resolution to your application. See also 'MP'.
MPEG4 is a widely used audio/video format created by the Moving Pictures Experts Group. As it relates to DVRs, it is one of the major encoding algorithms used, and offers greater compression and lower bandwidth requirements than JPEG2000, at a slight loss of visual quality. Typically DVRs labeled as MPEG4 utilize MPEG4 part 2, which is not to be confused by MPEG4 part 10 (H.264). See also 'H.264' and 'JPEG2000'.
The Open Network Video Interface Forum (ONVIF) is a global and open industry forum with the goal to facilitate the development and use of a global open standard for the interface of physical IP-based security products. Or in other words, to create a standard for how IP products within video surveillance and other physical security areas can communicate with each other. ONVIF is an organization started in 2008 by Axis Communications, Bosch Security Systems and Sony.
http://en.wikipedia.org/wiki/ONVIF_(Open_Network_Video_Interface_Forum) See also 'http://www.onvif.org/'.
Patrolling (sometimes called touring) is a feature of some pan/tilt devices that allows you to set a series of waypoints and have the device automatically cycle through them on a schedule.
Power over Ethernet, or PoE, technology describes a system to pass electrical power safely, along with data, on Ethernet cabling. The IEEE standard for PoE requires category 5 cable or higher for high power levels.
Presets, in RS485 parlance, are memory locations in a pan/tilt camera or device that allow you to store a particular position and easily recall it later.
PTZ is an acronym for Pan, Tilt & Zoom.
RS-485 is a 2 or 4 wire interface that is common among devices that support pan/tilt features. Most DVRs have support for controlling RS-485-enabled cameras and pedestals.
TVL is an acronym for TeleVision Lines, and is a measurement of resolution for composite video. It is not to be confused with the pixel resolution used to describe digital images. An average CCTV camera has about 480 TVL, while a high resolution camera would be 600 TVL or higher.
Unshielded Twisted Pair (UTP) is a type of cable primarily used in networking. It can also be used to send composite video over much longer distances than RG59/RG6 cable.