Surveillance Definitions

In cryptography, the Advanced Encryption Standard (AES) is an encyption standard adopted by the U.S. Government.  The standard comprises three block ciphers, AES-128, AES-192 and AES-256, adopted from a larger collection originally published as Rijndael. Each AES cipher has a 128-bit block size, with key sizes of 128, 192 and 256 bits, respectively. The AES ciphers have been analyzed extensively and are now used worldwide, as was the case with its predecessor, the Data Encryption Standard (DES).

AGC – Automatic Gain Control is an electronic system found in many types of devices.  Its purpose is to control the gain of a system in order to maintain adequate performance over a range of input signal levels.  Or an electronic circuit that tries to keep the video signal at a constant level (1volt peak-peak).  Useful on cameras working at low light levels.

AI – Auto Iris is an electronic circuit that acts as an iris on CCD cameras by electronically shuttering the CCD sensor.  Or an automatic method of varying the size of a lens opening in response to changes in scene illumination.

AWB – Auto White Balance is an electronic process used in video cameras to retain true colors.  It is performed electronically on the basis of a white object in the picture.

CCD – Charged Coupled Device:  It is analog technology.  The CCD camera has a little bit higher resolution than CMOS.  The camera also functions better in low light.  A CCD camera drains a little bit more power than the CMOS cameras.  It uses 12v instead of 9v.  A CMOS camera is smaller than a CCD camera and works longer with the 9v battery.

HAD CCD – Hole Accumulation Diode is a type of CCD sensor with a layer designed to accumulate holes (in the electronic sense), thus reducing noise level.

S to N Ratio -  Signal to Noise Ratio is simply the ratio of the signal power and noise power, expressed in decibels (db).  Or measure of noise on a video signal.  It is represented in decibels as the level of the video signal compared to the level of noise present on that signal.  The higher the signal to noise ratio the better.

BLC – Balance Light Control is a method to compensate for bright spots in a picture.  It is also important to consider whether there are bright spots in the picture such as car headlights which can make identification of the vehicle registration or model impossible.  This can also be a major problem where it is necessary to identify a person who is moving from bright daylight into artificial light.  This could result in the subject becoming an unidentifiable silhouette.

FL - Focal length is measured in mm or inches, and is the distance between the optical center of the lens and the point on which it focuses.  A lower focal length results in less magnification with a greater field of view, and vice versa for longer focal lengths.  Security cameras usually have a focal length of ¼”, 1/3”, or ½”.

OSD – On Screen Display is a method of displaying set-up information or instructions on to a display monitor.

Resolution – Resolution measures the camera's ability to reproduce an image.  The higher the resolution, the better the picture quality.

LUX – LUX is the measurement of low light needed for the camera to view and record properly.

FPS – Frames Per Second is the number of still frames (pictures) that give the illusion of motion, which appear in a single second of time.  30fps is considered “Real Time.”  So for Real Time viewing of your cameras, you need at least 30fps for each camera.

IR – Infrared, IR LEDS are used on Day/Night cameras which allow the camera to see in the dark.

FPS - Frames per Second - the number of still frames (pictures) that give the illusion of motion, which appear in a single second.  30 fps is considered "real time."  You need 30fps for each camera for real time viewing or recording with your cameras.

NTSC - National Television Standards Committee; the analog video representation standard used in the US and South America.  Compared to PAL.

PAL - Phase Alternating Line - the analog video representation standard used in Australia, and most of Europe and Asia.  Compared to NTSC.

Motion Detection - Refers to the feature in some VCRs and DVRs to only record video if something in the image moves or changes.  Therefore you don't have to look through hours of taped video looking for something to happen.  It also saves a lot of space on the tape or hard drive.

CODEC - A term referring to any technology used to compress and decompress large files such as audio and video files for efficient data transfer.

H.264 Compression - The latest MPEG4 compression technology, released in 2003.  H.264 provides excellent video compression.  You get the same quality image as MPEG4 even at the higher resolutions like full screen D1.

Digital Video Recorder (DVR) - A digital video recorder is basically a computer that converts the incoming (analog) signal from the cameras to digital, and compresses it, and stores it.  The DVR replaces the function of a multiplexor (or quad or switcher) and a security VCR.  There are many advantages of digital video recorders over their analog counterparts.