Some Great Offers On Camcorder Dvr Compare from Amazon
CCTV Security Systems Chennai India
Video surveillance information portal for CCTV Closed Circuit TV (CCTV)
CCTV is a collection of video cameras used for video surveillance.
CCTV differs from broadcast television as all the equipment directly associated with cables or wireless transmitters that can not be received by standard television aerials or equipment.The transmissions of video signals are only intended to be accessible to equipment its dedicated closed circuit.
CCTV is generally used in areas where there is an increased need for security, such as banks, airports and city centers. CCTV was Originally developed as a means to increase security for banks, but have over time developed into a cost-effective means of general video surveillance and home security.
A basic CCTV system consists of the following;
- Camera, lens and power supply.
- Recording Device, VCR or digital video recorder.
- A monitor.
- Wiring
CCTV Cameras
CCTV cameras are available in color, black and white or cameras that have the ability to switch between color and monochrome (day / night CCTV cameras). CCTV cameras that switches between color and black and white are calculated for environments with low lighting at different times. There are 2 reasons for using a CCTV camera that can switch between color and monochrome, monochrome cameras are much more sensitive to low light environments and monochrome CCTV cameras can also be used with Infra red lighting. When there is enough available light there is an additional advantage to using a color CCTV camera to record color information, for example, the color of a car or a person's clothing.
The primary function of a CCTV camera is to convert light into a video signal, all cameras require an optical lens to focus light on an image sensor located directly behind the lens inside the CCTV camera.
There are two types of image sensor is available, a CCTV camera with a CMOS (complementary metal-oxide semiconductor) image sensor chip and other more general type using a CCD (Charge Coupled Device) imaging sensor chip. Most of CCTV cameras and camcorders use a CCD image sensor, while the CMOS image sensors are more commonly used in webcams, budget home security cameras and digital photography cameras. CCD cameras are able to create a much clearer and higher resolution image.
Various types of surveillance cameras is board cameras, C mount cameras, IR cameras, IP cameras, zoom cameras, Speed Dome cameras.
All cameras require a power supply is normally 12 volts DC, 24 volts AC or 240 volts AC.
CCTV Lenses
As mentioned in the section on surveillance cameras, All cameras require an optical lens. The job of the lens is to limit and focus light on the image sensor of CCTV cameras. A lens can also automatically control the amount of light reaching the image sensor, these lenses called Auto Iris (AI) lenses and are generally used outdoors where the light is always changing during the day, at night and also in varying weather conditions.
It is also a task for the lens to check depth of field of the image, either a wide angle picture or a narrow-angle image depending the distance from the object from CCTV cameras. When the movable cameras use a zoom lens is usually fitted to allow different points of a monitored area to be seen. Zoom lenses are usually controlled by the CCTV operator.
CCTV Recording Devices
Recording The device receives and stores images from CCTV cameras in the past time lapsed VCR's and video multiplexers were generally used in CCTV systems, but because of developments in technology digital video recorders are now more commonly used.
Time lapse VCR's allow cctv camera images to be recorded for varying lengths of time a single 3 hours videotape, from lengths of 3 hours to over 960 hours. The problem with time lapse video recorders, is that the longer they are willing to absorb the smaller video information, they can record per second, equivalent to taking a photograph from 25 per second for a photo every 4 seconds for example.
Digital video recorders using computer hard drives to store the recorded data and may be up for much longer depending on the size of the hard disk and CODEC being used. A DVR combines and improves the recording capabilities in a time lapse VCR and a multiplexer.
CCTV VCR and CCTV Camera Switcher
When there is a requirement for admission to more than one CCTV camera and video switcher can be used, cameras are connected to switches and switch automatically switches the image fed to the screen and video. The disadvantage of using a switcher is that if there is an incident it is possible that the CCTV camera image will change causing the incident to be missed.
CCTV VCR and CCTV video multiplexer
A multiplexer is a device that takes multiple video images and put them on a VHS tape, using the properties of the PAL signal to include as many images from several surveillance cameras every second as possible. The video recorded data is limited by the amount of CCTV cameras on the system and the time the VCR set to record on.
CCTV Stand alone digital video recorder
A standalone DVR is designed specifically for CCTV systems. It uses computer hard drives to store video information, and an embedded operating system for control functions DVR, this type of recording device is most commonly used with existing CCTV systems. CCTV Digital Video Recorders have different settings to enable multiple video data to be recorded at the required times with technology such as video motion detection, this means that images from surveillance cameras are only recorded when the information of the image changes, for example a person walking in front of CCTV cameras.
As mentioned earlier, CCTV DVRs have a built- multiplexer, which allows the user to see more pictures on the screen at any given time by separation of the screen.
Many DVRs can also connected to a network or modem to allow remote access.
CCTV DVR Comes with High Contrast LCD Display called Media DVR.
CCTV PC-based digital recorder
PC based CCTV DVR operate much the same way as standalone CCTV DVRs, but use the video card and extra software to perform DVR operations, these types of DVR easily upgraded to accept additional cameras by adding more capture cards. As with standalone DVR's can be PC-based recorders also be connected to the Internet for remote access to DVR.
CCTV Network video server
Network video servers are designed for IP CCTV Cameras over WAN or LAN computer network, where each camera has its own unique IP address.
CCTV Monitor
There are two main types of monitor the analog monitoring is referred to as a CRT (Cathode Ray Tube) and the digital screen which is the commonly used PC screen known as TFT (Thin Film Transistor) screen.
There are advantages and disadvantages for both displays, A TFT monitor is less bulky than a CRT monitor. A CRT monitor will show a better picture of low-and middle-income solution cameras than a TFT screen. For high resolution cameras, a TFT screen to be more cost effective than using a high resolution CRT monitor.
CRT monitors are usually specially designed for CCTV systems and comes equipped with a composite video input BNC (Bayonet Nut Coupling) connector. CCTV monitors are also designed for prolonged use compared to standard TV and address the higher screen resolutions.
Developed in the late 1940's as a miniature Type C connector, Reciprocating Neil-Concelman (sometimes mistakenly called a British Naval Connector or Bayonet Nut Connector). A connector commonly used in CCTV industry, usually for coaxial cable. Easy to install and reliable with little video signal loss. A rotating ring outside the tube locks the cable to any female.
CCTV Lighting
All cameras require a degree of lighting that could pick up an image, generally monochrome cameras work well in darker environments than color cameras. Infrared lighting can also be used with monochrome cameras.
There are different types or infrared lighting available, standard bulbs or LED (Light Emitting Diode) type.
Infra-red lighting can illuminate areas at different frequencies, although invisible to the naked eye, can cameras see light. Depending on the spectrum that infrared light is depends on how visible the lamp filament is the naked eye. Note, however, not all cameras are sensitive enough to capture all the frequencies of infrared.
Covert CCTV Camera
Covert CCTV is the practice of using video cameras in places there has been obvious to those controlled by the dedicated CCTV camera coverage, but it is recommended that there is reasonable cause for the purpose of covert surveillance and that its primary objective is clearly used only for the purposes of preventing crime and has not spent longer than intended.
Remote CCTV
Remote CCTV is the means to access CCTV images via a computer network or standard telephone network. Software is used on local PC, giving access to the digital video recorder.
CCTV IP CAMERA
IP CCTV refers to Internet Protocol Closed Circuit Television; traditional CCTV systems use digital or analog cameras with analog cables connecting to a recording device as a digital video recorder. IP CCTV cameras are designed to put on any existing wired or wireless computer TCP / IP network, or directly on a broadband connection, so CCTV cameras can be accessed from any computer connected to the network, this includes the Internet.
Computers used on the network to store CCTV camera images, but with the flexibility of IP CCTV, CCTV cameras could be positioned on opposite sides of the world. Although IP cameras can be connected directly to an existing network, bandwidth is always a consideration, since the data sent from the CCTV camera is probably very larger than standard data transmitted over standard office network, which if not planned correctly, it can slow down the whole network.
CCTV Video Signal
The video signal is known as the moving image information signal from a camcorder, we use a video standard called PAL (Phase Alternate Line) is a color or monochrome video signal that consists of 25 pictures or frames per second. A new breed of cameras called IP CCTV cameras (closed Internet Protocol television) uses a data signal which consists of a series of electronic still images. These cameras are generally connected directly to a computer or computer network, which is available software to enable live viewing, recording and playback of video images. One format for this moving video data is called MPEG (Moving Pictures Experts Group).
CCTV Video Transmission
Video transmission is the means to get video signal from the camera for recording or monitoring device. Transmission may be carried over wires or by radio and television broadcasting via radio transmission.
The most commonly used cable for cable is RG6 coaxial cable.
Network cable is used more often as video is unable to travel further along twisted cables than the standard lure.
Other forms of video transmission include fiber optic cables, microwave transmission and unlicensed radio transmission.
CCTV Resolution
Resolution refers to the number of definable parts of the horizontal image produced by a camera, recorded by video or digital video recorder and displayed on the screen.
CCTV equipment manufacturers refer to this as TVL (TV Lines). At least 420 TVL is recommandable.
The TVL of the analog PAL video information is closely relative to pixels in a digital image.
VHS (Video Home System) recorders to record 300 lines of a monochrome image, or 240 lines of a color image, SVHS (Super Video Home System) capable of recording 400 lines monochrome image and 340 lines in a color image.
Recording Apparatus, the decisive factor when choosing the resolution of a camera as a 520 TVL camera to be admitted to a VHS recorder will only record 240 lines, out of the available 520 lines.
Digital Video Recorders (DVRs) have the advantage of being able to convert the analog PAL signal to a digital signal at different resolutions, downside is that the higher the resolution of the image recorded, the larger the file size that digital image. The conversion of the analog PAL signal to a digital image is done using a codec (compressor-decompressor).
CCTV Codec's
A CODEC is used to convert an analog video signal into a digital video signal using either hardware or software. Codec's plays an important role in digital video recorders, they are not only used to convert the analog signal to a digital signal, but also to produce the best quality video information at the smallest file size. It makes a big difference to the amount of video that can placed on a hard disk DVRs.
There are many standards for the CODEC used for video compression that you may come across is MPEG-2, MPEG-4, JPEG 2000, AVI and H.264, H.264 is the latest codec introduced in the CCTV market, arising from video conferencing equipment.
About the Author
ATSS-Active Total Security Solutions Provider Chennai India Provides Security Systems Information with related product details along with product working explanation, due to that the customer know their needs and they decide what they want.
www.videosurveillance.co.in
Camcorder Dvr Compare
One of the greatest challenges in working with today's smaller camcorders (with smaller chips) is getting a shallow depth of field for your shot. in my opinion, this is one of the major limitations of these cameras. since this is a well recognized problem, video professionals have come up with a variety of ways to handle this problem, which I will share here.
