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| CCTV Buyers Guide |
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 A Guide To Choosing CCTV Security Camera SystemsYou can have CCTV professionally installed, and, in some circumstances this may be appropriate. However modern technology has made CCTV products much more affordable and for the average DIY person, easy to fit. With such a large selection of cameras and prices, it is difficult to decide what to select. We have the following guide to help you choose the correct products. We also provide simple illustrations of fitting, from complete systems to fitting in domestic and commercial properties.'WIRE-LESS' A very popular system, wireless transmission is governed by regulations which allow licence-exempt systems to transmit signals up to 100 metres in line of sight. However this can reduce to about 30 metres when used indoors. Basic wireless cameras work on one frequency, this means you cannot use 2 cameras within 100 metres of each other. There are cameras and receivers with 4 selectable channels which allow for multi-camera systems. We also supply the small covert type of camera with its own built-in transmitter. See our product range. A 'wireless' camera requires a power source, this is usually obtained by plugging into the mains, making it not strictly 'wire-less'. Batteries, which have a finite life, are not suitable for permanent installations. The voltage required is in the range 9-12V DC. A power supply in the loft is often quite easily accessible. Wireless systems are used where running the video cable back to VCR or monitor is not viable. Wireless cameras can be used for temporary monitoring of stock rooms offices etc. Miniature wireless cameras, using battery power, can be fitted to model aircraft, trains, boats etc., with the receiver connected to a domestic camcorder, giving a realistic on-board experience. See our product range. 'WIRED' Wired cameras have virtually no interference and can be positioned a long distance from the monitoring/recording equipment. The cameras rarely need their own power supply. Normally one cable takes power and signal back to the recording device. We supply DIY kits where the camera is powered by the base unit, eliminating the need to plug the camera in to a mains outlet. See our product range. 'TYPES of CAMERAS' A traditional CCTV camera has an 'industry style' look, making it unsuitable for fitting to homes or shops. Top-end cameras are usually specified without a lens and are chosen to give the focal length required and field of view. There are two common types of CCTV cameras, CMOS and CCD (see Glossary of terms). CMOS based cameras are generally cheaper but do not produce such clear or sharp images. If there is a need to easily identify who or what is being captured and recorded, CCD cameras provide pin-point clarity and are best where clarity is needed. Integrated cameras and lenses are sealed to prevent moisture damage. This sealing process enables them to be used under water if required. They do not need a heater and their size makes them suitable for fitting to domestic and commercial properties. Because they are permanently sealed it is not possible to adjust these cameras. Many integrated cameras are fitted with a 3.6mm lens giving a 72deg angle of view which is suitable for most domestic and small commercial properties. We also have cameras with a narrower angle of view allowing the cameras to 'see' further - the angle of view for all of our cameras is stated within the bullet point copy. COLOUR OR MONOCHROME? The human eye sees and recalls things better if they appear in colour - it's easier to track down someone with a red top and blue skirt than a grey dressed person that would see in monochrome. Colour cameras are more expensive than monochrome, but they are also less sensitive making night usage an impractical option unless good lighting is available. Monochrome cameras can offer Infra Red (IR) sensitivity making their use with covert IR illumination possible. This can be useful where planning permission makes extra lighting impractical or the security requirement is such that intruders should not be alerted to the existence of CCTV surveillance. OUTDOOR CAMERAS If a camera is to be sited outside and is not going to be mounted in an enclosure it must be classed as weather resistant. All of our outdoor cameras are fully weatherproof. The cable entry points are sealed and most cameras come with trailing leads that allows the connections to be made inside the building. DAY/NIGHT CAMERAS Very popular in domestic and small commercial CCTV applications, day/night cameras allow great quality, colour recording during daylight hours. When light levels drop below a certain level the camera's infra red LED's allow the camera to continue recording good quality footage even in complete darkness. The distance the cameras will see at night is dependent on the strength of the LED's. See our The golden rule when deciding which camera to use for a given lighting condition is not to choose one that will only just give a picture. Try to give the camera approximately 10 times its quoted minimum scene illumination. Most cameras will be able to cope with excess light. The major problem is when they do not have enough light to produce a picture. RESOLUTION This is the horizontal resolution in TV lines, i.e., the number of black to white transitions that can be resolved across the image. This is a function of the number of pixels that make up the CCD imaging area and the bandwidth of the camera circuitry. Typical entry level camera resolution is 330 TV lines, with high resolution cameras producing better than 400 lines. Higher resolution costs more!. How do I display the picture from more than one camera?. Most CCTV systems deploy several cameras so you need a method to view and record the images. There are various ways this can be achieved; use a video switcher, a quad processor or a multiplexer. Here are the simple benefits of each system. Switchers A CCTV switcher is a unit that changes between camera pictures one at a time, the output being viewed on a monitor or passed to the recording device. As switchers can use any VCR to record in true real-time, the pictures can be of a very high quality. The fact that they provide true real-time recording unlike a snapshot from a multiplexer means they provide a superior picture quality. This can sometimes outweigh the disadvantages that switchers can only record one picture at a time. Advantages - Simple, low cost, good quality real-time pictures. Disadvantage - Can only record one camera at a time. Quad Processors Quad processors enable 4 camera pictures to be displayed simultaneously. They are useful where it is necessary to monitor several areas at the same time. As with a switcher, what is seen on the monitor is the picture that is recorded on your VCR. Advantages - Simple to use - shows multiple displays which can be recorded. Disadvantage - Records only 1 camera at a time real time or 4 at a quarter of the resolution. Multiplexers A multiplexer allows simultaneous recording of multiple full-sized camera pictures on to one VCR tape providing a more comprehensive record than with a switcher or a quad processor. Most have variable display options such as quad and picture in a picture allowing flexible surveillance of more than one camera at once. When to use a multiplexer Generally use when a high degree of surveillance is required and it is necessary to record full resolution pictures from a number of cameras at the same time. Advantages - Records all camera pictures full size on one tape - gives better monitoring of areas simultaneously - enables large areas to be monitored without losing surveillance due to camera switching time. Disadvantages - Does not record in real time - Raises the overall cost of the system. Recording CCTV Images Domestic VCR The simplest low-cost solution is to use your home VCR. This will typically give 8 hours recording time and can be used in conjunction with a Video Activator to provide event-only recording. We sell wired and wireless kits consisting of cameras with built-in motion detectors plus VCR activators. Recording will automatically be triggered on motion detection. Advantages very low cost. Worth considering buying a seperate VCR for camera recording. This VCR can be hidden in the attic or a cupboard making it less likely to stolen by an intruder. Disadvantages most domestic recorders have a slow "take-up" time. (the time taken to start recording) - cannot use the VCR to record TV channel whilst camera input is selected. Time-lapse VCR Similar to your home VCR but with a slower-moving tape that records the camera pictures as snapshots at split second intervals. The time-lapse can be set to give 24, 240 or 960 hours of recording on standard VCR tapes. Advantages very long recording time, cost-effective. Added features like alarms, auto tape-rewind. Disadvantages will need a quad processor or multiplexer when recording multiple cameras which adds to the cost of the system. the longer the recording time the longer the period of time between the snapshots. tapes do wear out through over use. DVR Digital Video Recorders can record images onto a built-in hard drive from one or more cameras. DVRs normally come combined with multiplexer functions and are generally considered the future of CCTV recording. DVRs can generally be split into two groups - standalone black box and PC-based solutions. PC-based solutions are discussed in their own section. Advantages all-in-one box for recording, multiplexing, alarms and motion detect. higher resolution than S-VHS VCR is possible near instant access to recording from known time and date no loss of quality when copies taken can record events in real-time before an alarm actually occurs with "Pre-event trigger" enhanced playback function, forward and reverse frame by frame playback easily connect to networks/internet for remote viewing and playback. PC-based Systems If you already have a PC then with the addition of a video-capture card and surveillance software you have a powerful digital system. The purchase of a video capture card and software is a very cost effective method of providing a high specification system. Advantages easy to expand 2 ports to 4, 8, or 16 ports. Simply buy another card remote viewing software allows for many configurations for monitoring e.g. quad display records in real time, simultaneously from all cameras time and date stamping with motion detect alert wizard, send email with photo or video clip, SMS alert audio alert motion detection recording featuring different sensitivity settings and masking feature. Only movement in the masked rectangle trigger a response. By careful positioning of the rectangles you can allow for pet movement within the observation area. a low-cost, all-in-one solution that does away with the need for separate motion detect, splitters, quads or multiplexers. Tips on fitting CCTV to your house. The prospect of drilling a hole through the outside wall of your house to run the power and video cable for a camera may seem a big job. With a little forethought it can be quite simple. Positioning of cameras Most people want to hide the camera as much as possible. The modern 'bullet-type' camera is no bigger than your small finger and can easily be located under or on the fascia/soffit boards where the roof meets the wall. When located here it is sheltered from wind and rain and can be shaded from most sunlight. The height of the camera gives a good area of view and minimises the risk of vandalism. Another advantage of this location is cabling. It is pretty easy to run the cables into the loft from this position. Many houses have a small ventilation gap between the roof tiles and the external wall, or a small hole may be drilled in the fascia board to gain access to the loft. Cabling It is usually quite easy to pick up mains power in the loft or, if additional cabling is required it is now internal. Wireless transmission can be used for the video signal with the receiver being placed next to the monitor or recorder (TV, VCR, PC etc.). That's it, job done. A 'hard-wired' system is almost as easy to install. Locate the TV aerial down-lead that may be in the loft or run down the outside of the house, then run the CCTV camera video cable alongside the aerial cable, which will lead directly to the TV. A good method of connection is an RF modulator. This changes the camera's video output to an RF output. You can pipe the CCTV images down the existing TV aerial down-lead and view on the TV/VCR as if it were another channel. If your house is fitted with a TV distribution system, this method will allow the pictures to be seenon all the TV sets. Addition of Switchers etc. Consider placing switchers, mutiplexers or DVRs in the loft. This keeps all the cabling in the loft with just one output cable to your monitor. It also hides your recording device. If you dont understand any of the terms used, please see our CCTV Glossary. NOTE Disclaimer. 'Dropshipservices' accept no responsibility for any damage or injury caused to or by any person or persons, building, structure etc., howsoever caused by anyone following or attempting to follow, any of the 'tips' shown. All such occurrences shall be the sole responsibility of the person or persons involved. Glossary of Terms for CCTV Equipment AC Adapter Alternating Current Adapter; when plugged to 240 volts/ 50Hz AC Power (usually 117V AC/60Hz in the United States) it produces 12V DC, 24V AC or others. "UL Listed" and "Regulated" recommended. It is also called Power Transformer. AC Power Alternating Current Power. In the UK, the standard AC Power is single-phase 240V AC/ 50Hz and is provided from power outlets in the house. 24V AC power can be produced from an AC Adapter. AGC (Automatic Gain Control) Automatically adjusts the video quality in low light condition. Alarm Sensor Like Video Motion Detector, detects changes of motion to produce an alarm. ALC (Automatic Light Control) Allows the auto-iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows. Select this mode when an auto-iris lens is used. Algorithm A procedure or formula for solving a problem. Analogue (Analog) Continuously variable numerical values such as voltage, current, etc.(The CCD camera produces analogue video signals.) 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. ANSI American National Standards Institute. This organisation is responsible for approving U.S. standards in many areas, including computers and communications. Aperture The light gathering area of a lens, controlled by the iris. ARP Address Resolution Protocol; for mapping an IP address to a physical machine address. ASCII American (National) Standard Code for Information Interchange. A standard character-to-number encoding widely used in the computer industry. ASIS American Society for Industrial Security. Aspect Ratio The ratio of the vertical to the horizontal image size; 3:4 is the NTSC standard. Aspherical Lens A lens designed with a non spherical shape so that it passes more lights or decreases barrel distortion on wide angle lenses. Attenuation A decrease or loss in a signal, usually measured in decibels. Auto-focus Lens Automatically adjusts the lens focus from surrounding scene and keeps a moving object in focus. Automatic Gain Control (AGC) Automatically adjusts the video quality in low light condition. Automatic Iris (Auto-iris) A diaphragm device in the lens that adjusts to light level changes. The iris diaphragm opens or closes the aperture to control the amount of lights coming through the lens. Automatic Level Control (ALC) Allows the auto-iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows. Auto Terminating Automatically select the correct termination depending on whether the video output is connected. Auto White Balance (AWB) Automatically adjusts a colour camera's colour to maintain white areas. Bandwidth The capacity of the transmission medium stated in bits per second or as a frequency. Or, the amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second (bps) or bytes per second. For analogue devices, the bandwidth is expressed in cycles per second, or Hertz (Hz). Back Light Compensation (BLC) Electronically compensates for high background lighting to give detail which would normally be silhouetted. Baud A unit of measurement that denotes the number of bits that can be transmitted per second. For example, if a modem is rated at 9600 baud it is capable of transmitting data at a rate of 9600 bits per second. Bifocal Lens A lens system that has two different focal length lenses and images two identical or different scenes onto a single camera sensor. The two captured scenes appear as a split image on the monitor. Binary A numbering system with only two values: 0 (zero) and 1 (one). Bit Abbreviated with small "b". Binary Digit. The smallest unit of data in a computer. Blanking The process whereby the beam in a CRT is cut off during the retrace period. BLC (Back Light Compensation) Electronically compensates for high background lighting to give detail that would normally be silhouetted. BNC Bayonet Neil-Concelman or British Naval Connector. A connector widely used in the CCTV industry, usually for coaxial cable. Easy to install and reliable with little video signal loss. BPS Bits Per Second is the unit used for measuring line speed, the number of information units transmitted per second. 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. Browser An application program that provides a way to look at and interact with all the information on the World Wide Web. Nets cape and Microsoft Internet Explorer are the two browsers that vast majority uses. Byte Abbreviated with capital "B". A unit of data that is eight bits long and is used by most computers to represent a character such as a letter, number or symbol C-Mount An industry standard for lens mounting. C-Mount is 1-inch diameter with 32 threads per inch. A C-Mount lens needs C-ring when it is mounted at a CS-Mount camera. C-MOS Complementary - Metal Oxide Semiconductor. A video image sensor chip that produces much lower quality picture than CCD chip. 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. CATV Cable Access Television. CCD Charge Coupled Device. A video image sensor chip. CCIR International Radio Consultative Committee; has made the technical recommendation for the European 625 line standard for video signals. CCTMA Closed Circuit Television Manufacturers Association. CCTV Closed Circuit Television. It does not broadcast TV signals but transmits them over a closed circuit through electrically conducting cable or wireless transmitter and receiver. CCTV Camera A part of the CCTV system that captures the video pictures. CCTV Monitor A part of the CCTV system that receives the video pictures from a CCTV camera and displays them. Coaxial Cable A cable that can carry a wide range of frequencies with very low signal loss. It consists of a metallic shield with a single wire placed along the centre of a shield and isolated from the shield by an insulator. Colour Saturation The degree of mixture of a colour and white. High saturation means little or no white. Composite Video Signal A combined signals in a television transmission. The picture signal, blanking signal, and vertical/horizontal synchronising signals are all combined. CRT Cathode Ray Tube. The vacuum tube part of a monitor or television. CS-Mount An industry standard for lens mounting. CS-Mount is 1 inch diameter with 32 threads per inch. A C-Mount lens needs C-ring when it is mounted at a CS-Mount camera. Date/Time Generator Installed between a CCTV camera and a monitor, it generates the information of Date, Time and camera ID. 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. Decibel (dB) The power or voltage ratio of two signals. DIP switches Dual Interface Poll switches usually allow you to change the configuration of a circuit board to suit your application. DMZ Detection of Motion Zone DHCP Dynamic Host Configuration Protocol; lets network administrators manage centrally and automate the assignment of IP addresses in an organisation's network. DIN Multi-wire cable with DIN connectors at both ends. Usually has 5 or 6 inner wires. Different diameter and configuration from maker to maker. Distortion A general term when the object is not shown exactly as is. DNS 1) Domain Name System. A general purpose distributed, replicated, data query service. Its principal use is the lookup of host IP addresses based on host names. 2) Domain Name Server. A computer that converts host names, such as www.pelikancam.com to its corresponding IP Address, such as 67.100.253.111 DRAM Dynamic Random Access Memory. Most common RAM (Random Access Memory) for PC. DSL Digital Subscriber Line. A technology for bringing higher-bandwidth information to homes and businesses over ordinary copper telephone lines. DVR Digital Video Recorder; records video pictures digitally. Dwell Time The length of time a switcher displays one camera before sequencing to the next. EIA Electronic Industries Association. American standard for B/W camera system. ELC (Electronic Light Control) Compensates for moderate light changes in indoor applications without the use of auto iris lenses. Select this mode when a fixed iris lens or manual iris lens is used. Electronic Shutter Compensates for moderate light changes in indoor applications without the use of auto iris lenses. EMI Electro-Magnetic Interference. Ether net The most widely installed Local Area Network (LAN) technology. Specified in a standard IEEE802.3.10/100 BASE-T, the most commonly installed Ether net system, provides transmission speed up to 100 megabits per second. Extranet A private network. It uses the Internet Protocol to securely share part of a business information with suppliers, vendors or others FCC Federal Communications Commission; controls also wireless camera system as one of the commercial broadcasting systems. FFL Fixed Focal Length Lens Fiber-Optic Cable One of the video transmission ways, being used for a long distance transmission up to miles. Field One video frame is composed of two fields; one field consists of the odd numbered lines in the frame and the other field consists of the even numbered lines. Field Frequency The number of fields per second. Field Of View FOV. The width, height or diameter of a scene to be monitored. Usually determined by the focal length of a lens, the sensor format and the distance to the objects. Firewall A set of programs that protects the resources of a private network from outside users. FL Focal Length. The distance from the centre of a lens (or, the secondary principal point, if it has) to the focal point (sensor). The longer the focal length, the narrower is the angle of view. Flange-back Adjusting Ring Some models of CCTV cameras have built-in Flange-back Adjusting Ring, which adjusts the back-focal distance or picture focus. A C-Ring (5mm spacer ring) is not required when a C-Mount lens is to be mounted to a camera that has built-in Flange-back Adjusting Ring. Flash Memory Or flash RAM (Random Access Memory). A type of constantly powered non-volatile memory that can be erased and reprogrammed in units of memory called blocks. f-number (f-stop) Optical or lens speed. Smaller f-number means faster lens. Focal Length FL. The distance from the centre of a lens (or, the secondary principal point, if it has) to the focal point (sensor). The longer the focal length, the narrower is the angle of view. FOV Field of View. The width, height or diameter of a scene to be monitored. Usually determined by the focal length of a lens, the sensor format and the distance to the objects. 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. Frame Frequency The number of frames per second. The frame frequency is half the field frequency. FTP File Transfer Protocol. A way to exchange files between computers on the Internet Gamma Degree of contrast in a video picture between output magnitude and input magnitude. GB Gigabyte. Genlock A device that adjusts the frequency of internal sync to an external data. Ghost A shadowy or weak image in the received picture, offset to either the right or to the left of the primary image. HTML Hyper Text Mark-up Language. A set of codes inserted in a file intended for display on a World Wide Web browser page. HUB As a network product, a hub may include a group of modem cards for dial-in users, a gateway card for connections to a Local Area Network (LAN), and a connection to a line. Hz (Hertz) Cycles per second. ICMP Internet Control Message Protocol. A message control and error-reporting protocol. Impedance Electrical characteristic of a system or component, expressed in ohms. CCTV industry has standardised 75-ohm impedance. Infrared (IR) Light Invisible light beyond the 750 nanometers (red end of the visible lights). INT Internal sync mode that sets to internal 2:1 interlace. Intra net A private network. It may consist of many LAN and/or WAN. IP Internet Protocol. A set of rules to send and receive messages at the Internet address level. Iris An adjustable opto-mechanical aperture built into a camera that controls the amount of lights coming through the lens. ISDN Integrated Service Digital Network. A set of standard for digital transmission over ordinary telephone copper wire. JPEG Joint Photographic Experts Group. A graphic image file or a image compression algorithm. KB Kilobyte Kbps Kilobits per second. A measure of bandwidth. LAN Local Area Network. A group of computers and associated devices that share a common communications line. LED Light Emitting Diode. Lens Mount The area where a lens is mounted. There are two types; C- or CS-Mount. Lens Speed Optical speed, expressed by f-number. Smaller f-number means faster lens. Linux An UNIX-like operating system. Very efficient and fast-performing system. LL Line Lock mode LNB (Low Noise Block Converter) The part of satellite dish that hangs off of the arm and looks like a flashlight. It is what captures the digital signal from the satellite. Lux Lumens per Square Meter; unit of illumination amount. MATV Multiple Access Television. The method of distributing TV signals by broadcasting them through the air. MB Megabyte Mbps Megabits per second. A measure of bandwidth. Mini-DIN Multi-wire cable with Mini-DIN connectors at both ends. Usually has 4 inner wires. Monochrome Signal Black and White signal. MOD (Minimum Object Distance) The closest distance a lens will be able to focus upon an object. Wider angle (shorter focal length) lenses generally have a smaller MOD than larger focal length (narrower angle) lenses. MOS Metal-oxide Semiconductor. One of video image chips like CCD, but it produces lower quality video. Motorised 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 Moving Picture Experts Group. A standard for a digital video & audio compression. Multiplexer (MUX) Combines two or more video/audio signals into one channel. Usually accepts 10 or 16 video inputs and displays them in various formats. Network A series of points or connection points interconnected by communication paths. Noise Undesired signals that corrupt the original video signals and may reduce the image quality. NTSC National Television System Committee; formulates standards for American colour television system. NTSC system has 525 horizontal scan lines and 30 frames per second. NVR Network Video Recorder. A software or computer that records video on the hard disk. Like a DVR, it usually records digitally so the user can instantly search by time, date and camera. It collects video from network camera, network video server or DVR over the network. Optical Speed Lens speed, expressed by f-number. Smaller f-number means faster lens. Optical Axis Optical centreline that passes through the centre of a lens or mirror, etc. PAL Phase Alternating Line system. A colour television system used in Europe, Australia, parts of Africa and the Middle East. It has 625 horizontal scan lines and 25 frames per second. Pan and Tilt A Camera mounting device that allows movement in both side ways and up or down. Pan Rotating or scanning a camera side ways to view an area in a horizontal direction. Peak-To-Peak The amplitude difference between the most positive and the most negative excursions of a signal. Picture Element (Pixel) Photo sensor site in an image sensor like CCD chip; converts the input light image to an electronic signal. Pinhole Lens A lens with a relatively small front opening so it can be used in covert application. Pixel Picture Element. Photo sensor site in a image sensor like CCD chip; converts the input light image to an electronic signal. PPP Point-to-Point Protocol. For communications between two computers using a serial interface. PPPoE Point-to-Point Protocol over Ether net. Presets The pre-positioning of pan, tilt and zoom cameras by the use of potentiometers in the moving parts of the camera head. These allow the control equipment to store and move to a set reference point when the controller dictates or when an alarm exists. Protocol A special set of rules (in information technology). PSTN Public Switched Telephone Network. Quad Splitter Combines up to 4 video inputs into one channel and displays them on one monitor screen split into 4. RAM Random Access Memory. The place in a computer where the operating system, application programs, and data in current use are kept temporarily so that they can be quickly reached by the computer's processor. RARP Reverse Address Resolution Protocol. For host machines that don't know their IP address. RCA The Radio Corporation of America; conveniently used to describe phono jack and plug, one of the audio/video connectors. Resolution Expressed by TV lines or pixels, it indicates the quality level of video images. RF Radio Frequency. RG59/U Cable One of coaxial cables suitable for video transmission in CCTV system. Router A device on the Internet that determines the next network point to which a data should be forwarded. RS-232 Port A communication port with 15 pins. SECAM Sequential Couleur A'Memorie, a colour television system used in France, Russia and other countries that do not use either the NTSC or PAL system. It has 625 horizontal scan lines and 25 frames per second. Sequential Switcher Video 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. Server A computer program that provides services to other computer programs in the same or other computers. Or, the computer that a server program runs. Signal-to-Noise(S/N) Ratio The ratio between the television signal and the noise; expressed in decibel (dB). The higher the number the better. SMTP Simple Mail Transfer Protocol. TCP/IP used in sending and receiving e-mail. Switcher Sequential Switcher or Video 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. SVHS (Super Video Home System) Super VHS; a higher quality extension of the VHS home videotape format. S-Video Transmits luminance and colour portions separately, using multiple wires, thus avoiding the colour encoding process and its inevitable loss of picture quality. TCP Transmission Control Protocol. A set of rules to exchange messages with other Internet points at the information packet level. 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. Time Lapse VCR A video recorder that can be set to record continuously over long period of time. This can be anything from two hours to 960 hours. VHS Victor Home System; used by most VCRs as the recording medium. Video Band The frequency band used to transmit a composite video signal. 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. WAN Wide Area Network. Wave let A mathematical function useful in digital signal processing and image compression. In the Internet communications, wave let has been used to compress images to a greater extent than is generally possible with other methods such as JPEG or MPEG. Web Camera (or Web Camera Server) A CCTV Camera with built-in web server computer. Web Server The computer program (housed in a computer) that serves requested HTML pages or files. Zoom Lens A lens of continuously variable focal length. Data Protection Act Any CCTV system used to record images of individuals must comply with the requirements of the Data Protection Act 1998. Failure to do so may result in a fine by the government of up to £5000 for the system owner. Some systems may be exempt from the act, an example of this, is one that is installed in a private residence. Requirements: Registration The system owners must notify the Government’s Information Commissioners Office that they are processing data in the form of CCTV recordings. This can be done by post (call 01625 545700 to request an application form) or on-line at www.dataprotection.gov.uk. The charge for registering is currently £35. Notification Signs must be mounted adjacent to the entrance to areas where CCTV is in operation. For external areas where CCTV is in operation signs should be fitted to the perimeter or approaches. Security Recording equipment (i.e. Video Recorders, including Hard Drive and PC based systems, etc...) and Recording Media (i.e. Video Cassettes, Hard Drives, etc...) should be held in a secure area (such as a locked room or office) or in purpose made secure storage cabinets and accessible only by individuals responsible for the operation of the system. Logging All non-hard drive recordings, i.e. on to video cassettes, CD’s, video prints, etc must carry a unique serial number that links with an entry in to a recordings log book. Erasure For all non-hard drive based systems, the medium (i.e. video cassettes, etc...) on which the images are captured should be erased before re-use so that images are not recorded on top of images recorded previously. At the end of a recording mediums useful life it is recommended that you destroy it. Privacy All recordings must be held in a secure manner accessible only to individuals and organisations named in a site-specific code of practice. If cameras are capable of viewing areas where an individual may have a reasonable right to privacy e.g. within his/her home some form of physical masking or electronic privacy zoning should be installed.
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