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. CMOS camera is smaller than a CCD camera and works longer with the 9v battery.

CMOS - Complementary Metal Oxide Semiconductor:  a lower resolution camera compared to a CCD model.  The advantage of a CMOS camera is that is uses lower operation current.

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 ia 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.

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

Resolution - Resolution measures the cameras 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.

Focal Length - the distance from the surface of a lens and its focal point.