JPEG JPEG is a standard for coding/compression of still pictures. It is used in the CCTV systems to compress and store individual frames of video.
Lens An optical device for focusing a desired scene onto the imaging device in a CCTV camera.
Line Lock In CCTV, this usually refers to multiple cameras being powered by a common alternative current (AC) source (either 24 V AC, 110 V AC or 240 V AC) and consequently have field frequencies locked to the same AC source frequency (50 Hz in CCIR systems and 60 Hz in EIA systems).
Loop This refers to connecting an additional device in parallel with an existing video cable. For example, when driving a video recorder as well as a monitor from the same video signal.Most good quality DVRs now come with loop connectors allowing you for instance to record that camera onto the DVR and still at the same time stream just that picture to a selected TV or Monitor.
Matrix Switcher This is a device that allows any of its camera inputs to be switched to one or more of its monitor outputs. The outputs can of course also be video recorders.
Monitor The device used to view video pictures. These devices do not normally have television RF frequency receivers. They normally have composite or component video inputs.
Monochrome This refers to a black and white image rather than a color one.
Motion Detection A system that uses the video signal from a camera to determine if there is any movement in the picture and sets off an alarm or triggers the recorder to start recording.
Motorized Lens A camera lens equipped with small electric motor that enables focusing lens, opening or closing the iris diaphragm, or changing the focal length.
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.
Network Camera This refers to a camera that is designed to record pictures and transmit them directly over a computer network or dialup internet connection. Network cameras normally do not have any analogue video outputs. The images are encoded directly in one of the standard compression techniques, such as JPEG or MPEG.
Noise Undesired signals that corrupt the original video signals and may reduce the image quality.
NTSC This is standard for TV signals developed by the National Television Standards Committee in the USA. The UK, Australia and Europe, use a similar, but different standard known as PAL.
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.
PPPoE Point-to-Point Protocol over Ethernet.
Protocol A specific set of rules, procedures or conventions relating to format and timing of data transmission between two devices. A standard procedure that two data devices must accept and use to be able to understand each other.
Quad Splitter A device that compresses up to 4 video signals and simultaneously displays them on a monitor.
RARP Reverse Address Resolution Protocol. For host machines that don’t know their IP address.
RCA A device on the internet that determines the next network point to which a data should be forwarded.
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.
Router A device on the internet that determines the next network point to which a data should be forwarded.
RS-232 A format of digital communication using a three wire unbalanced presentation. The RS-232 standard defines the presentation and voltages for asynchronous communications, but it does not define how the data should be represented by the bits, i.e., it does not define the overall message format and protocol. It is very often used in computers, CCTV and communications between keyboards and matrix switchers.
RS-422 This is an advanced format of digital communication when compared to
RS-232. A major difference is that the presentation is balanced line and the signalling is differential. In simple terms, the signal transmitted is read at the receiving end as the difference between the two wires without a reference to earth. So if there is common mode noise induced along the line, it will be cancelled out. RS-422 can drive lines of up to 1200m and distribute data on to up to 10 receivers.
RS-485 This is an advanced format of digital communications compared to RS-232. It is a balanced line transmission system. The major improvement over RS422 is in the number of receivers that can be driven with this format, up to 32. It is classically a half.
Serial Interface A digital communications interface in which data are transmitted and received sequentially along a single wire or pair of wires. Common serial interface standards are RS-232 and RS-422.
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.
SMTP Simple Mail Transfer Protocol. TCP/IP used in sending and receiving e-mail.
Starlight Cameras A technology that utilises the small rays of starlight lighting to enhance a darkened image and show up as a much clearer brighter image.
S-Video Transmits luminance and color portions separately, using multiple wires, thus avoiding the color encoding process and its inevitable loss of picture quality.
TCP/IP Transmission Control Protocol / Internet Protocol. The basic communication language or protocol of the Internet.
Time/Date Generator Installed between a CCTV camera and a monitor, it generates the information of Date, Time and camera ID.
Termination This refers to a 75 Ohm terminator that is used to terminate each end of a video line.
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 (Normally CMOS cameras). 420 TVL or greater is considered high resolution (CCD cameras).
Twisted-pair A cable composed of two small insulated conductors twisted together. Since both wires have nearly equal exposure to any interference, common mode noise is high, but the differential noise is slight thus common mode noise is rejected in a twisted pair line. Twisted pair cable is used for balanced line transmission.
Vari-Focal 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.
Videocassette Recorder (VCR) A device that accepts signals from a video camera / microphone and records video/audio on magnetic tape in a cassette. The VCR can play back recorded video/audio on a television set or CCTV monitor.
Video Switcher Switcher or Sequential Switcher. A device that allows the video signals from multiple cameras to be displayed on a monitor, or recorded on a VCR one at a time in sequence.
Video Server This is a device that accepts inputs from CCTV cameras using the PAL, composite video signal. It digitizes the signal and then transmits images via a network, dialup or GSM connection. Advanced video servers have built-in video motion detection, and can buffer images while they are being uploaded to a remote server, where they are recorded.
Wavelets This is a compression technique used to give high compression without degrading the image quality.
Y/C A method of sending video pictures in 2 separate parts down 2 separate cables. The component parts are Y and C.
ZOOM LENS A lens with the ability to change its focal length manually or through the use of a controller to cover a variety of needs.
ZOOM RATIO The ratio of the starting focal length (wide) to the ending focal length (telephoto) of a zoom lens. A 10X zoom will magnify the image at the wide end by 10 times. Examples of a 10X zoom lenses; 8mm~80mm, 12mm~120mm.