Alarm Sensor - Like Video Motion Detector, detects changes of motion to produce an alarm. Angle of View - The scene angle that a video camera lens can show on the monitor, like Diagonal Angle, Horizontal Angle and Vertical Angle, usually described in degree. Auto-Focus Lens -Automatically adjusts the lens focus from surrounding scene and keeps a moving object in focus. Automatic Gain Control (AGC) - This is a feature of many CCTV cameras that helps keep the strength of the output signal constant, even when the light level changes. In other words, it boosts the signal strength at low light levels, and caps it at higher levels. Auto Iris (AI) -Cameras with an Auto Iris feature, have the ability to compensate for large variations in light levels. Particularly useful for cameras that need to compensate for changes from bright sunlight to dark shadows. The auto iris circuitry is normally linked to a motorised iris drive that physically opens and shuts the iris on the lens. Closing a physical iris is a much better way to protect a camera from being damaged by bright sunlight then simply using electronics to reduce the signal strength. Automatic White Balance (AWB) -This is a feature of some cameras that automatically adjusts the color settings to maintain the quality of the white areas of the image. Back Focus -This is the alignment of the rear of the lens to the imaging device. Back Light Compensation (BLC) - This is a feature of cameras that automatically adjusts the image to compensate for bright sunlight or bright lights, to give more detail on the darker areas of the image. For example to focus on the detail of a face of a person that has the sunlight shining from behind. Brightness Control- The manual bias control on a cathode ray tube or other display device that controls the average brightness and the contrast of a picture. BNC Connector - BNC is a bayonet style connector for coaxial cable that is most commonly used for CCTV installations. Camera Format - Video camera's CCD chips format; 2/3", 1/3", 1/4", etc. Camera Sensor -Video image sensor. CCD or C-MOS chip. CCD - Charge Coupled Device. One of the two main types of image sensing device used in cameras. It operates by converting light energy into electrical charge. CCTV Camera - A unit containing an imaging device that produces a video signal in the baseband form, usually with synchronization pulses and color information (composite video). C Mount Lens & CS Mount Lens - CCTV lenses are available in two different lens mounts. "C-mount" lenses have a flange back distance of 17.5mm vs. 12.5mm for "CS-mount" lenses. Many of today's cameras can accept either type of lens, but it is important to make sure that camera and lens. Compression - Digital video pictures can be compressed with a number of techniques. These include, JPEG, M-JPEG, MPEG and Wavelet. Day/Night Camera - A camera that displays color pictures in good lighting conditions, and automatically switches to B/W in low light conditions. DC Power - Direct Current Power; can be derived from an AC adapter or from a battery. Among DC voltages of 6, 9, 12, 24, 28, 12VDC is most common in the CCTV industry. Digital Video Recorder (DVR) - Also known as a personal video recorder (PVR) or hard disk video recorder. DVRs store recordings on a large hard drive, and most let you pause and replay live television. When used with an electronic program guide service, you can find and record shows automatically. Electronic Iris (EI) - This is an electronic implementation of an auto iris. It uses electronics to simulate the effect of opening and closing the iris, by increasing or decreasing the effective shutter time of the camera. Electronic Shutter (ES) - Compensates for moderate light changes in indoor applications without the use of auto iris lenses. Format - The size of the cameras imager. Current standards are 1/2, 1/3, 1/4 inches. Frame - A whole video image; is composed of two interlaced fields. A CCD chip produces 30 frames per second at NTSC system and 25 frames at PAL.
Gamma - Degree of contrast in a video picture between output magnitude and input magnitude. HAD - Hole Accumulated Diode. A type of CCD sensor with a layer designed to accumulate holes (in the electronic sense), thus reducing noise level. Image Device - The detector in the camera, either a tube or CCD solid state device.
Image size - Reference to the size of an image formed by the lens onto the camera pickup device. The current standards are: 1", 2/3", 1/2" and 1/3" measured diagonally. Infra Red (IR) - Low frequency light below the visible spectrum. This is often used for covert or semi-covert surveillance to provide a light source for cameras to record images in dark or zero light conditions. Iris - This is a mechanical device that adjusts to vary the amount of light passing through the lens of a camera. Lens - An optical device for focusing a desired scene onto the imaging device in a CCTV camera. Lux - Light unit for measuring illumination. It is defined as the illumination of a surface when luminous flux of 1 lumen falls on an area of 1 m2. It is also known as lumens per square meter. One lux is equal to approximately 0.09290 foot candle. MPEG - MPEG is a standard used for coding and compression of moving images. It was developed by the Moving Pictures Experts Group. It is now used widely for the compression of video images. However MPEG isn't just one standard. They have developed several standards for different uses. For example MPEG-2 is used for DVD's and set top boxes. MPEG-4 was developed for multi-media applications for fixed and mobile web applications. PAL - This is the standard for TV signals used in the UK. It stands for Phase Alternating Line. Pan and Tilt - A camera mounting device that allows movement in both side ways and up or down. Pixel - The smallest cell or area in a picture. The greater number of pixels, the higher the resolution of the scene. Resolution - Measure of a camera’s ability to reproduce details. Higher numbers are better. Remote control - A transmitting and receiving of signals for controlling remote devices such as pan and tilt units, lens functions, wash and wipe control and similar. It may also refer to the hand held controls for some VCRs and other CCTV equipment. S/N Ratio - Signal to Noise Ratio. This is the ratio between the signal strength and the noise levels on an audio or video signal. TCP/IP - Transmission Control Protocol / Internet Protocol. The basic communication language or protocol of the Internet. Television Lines (TVL) - This is a measure of the resolution of a video device. Higher number is higher resolution. 380 TVL is considered medium resolution. 470 TVL or greater is considered high resolution. Vari-Focal s -This refers to a type of lens that has the facility to change the focal length. This allows adjustment of the magnification and field of view of the camera. Motion Detection - A system that uses the video signal from a camera to determine if there is any movement in the picture and set of an alarm. Zoom Lens - A lens of continuously variable focal length.