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CCTV Security Systems Chennai India

Video Surveillance Information portal for CCTV closed circuit TV (CCTV)

CCTV is a collection of video cameras for video surveillance.

CCTV differs from broadcast television and all equipment is immediately connected with cables or wireless transmitters that can not be received by standard TV antenna or a Siemens-broadcast of the video signals are only intended to be accessible by the equipment at its special closed circuit.

CCTV is generally used in areas where there is an increased need for security, such as banks, airports and urban centers. CCTV was initially developed as a means to increase security for the banks, but over time has evolved 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 or black and white cameras with the ability to switch between color and monochrome (day / night CCTV cameras have). The CCTV cameras that switch between color and black and white are designed for environments with low lighting at different times. There are two reasons for using a CCTV camera that can switch between color and black and white, black and white CCTV cameras are much more sensitive to low light environments, and black and white CCTV cameras can also be used with Infra red lighting. If enough light is available, there is the added benefit of using a color CCTV camera to record color information, eg the color of a car or a clothes person.

The primary function of a CCTV camera is to light into a video signal, all CCTV cameras require an optical lens to light concentrating on an image sensor located directly behind the lens of the CCTV cameras.

There are two types of image sensor is available, a CCTV camera with a CMOS (Complementary Metal-Oxide Semiconductor) image sensor chip and the other more common type that a CCD (Charge Coupled Device used) image sensor chip. The majority of CCTV cameras and video camcorders use a CCD image sensor, and CMOS image sensors are increasingly used in webcams, budget, internal security cameras and digital photography cameras. CCD cameras are capable of a much clearer and higher resolution image.

Different types of CCTV cameras board cameras, C Mount Cameras, IR cameras, IP Cameras, Zoom Camera, Speed Dome Camera.

All CCTV cameras require a power supply that are generally 12 volts DC, 24 V AC or 240 volts AC.

CCTV Lenses

As mentioned in the chapter on CCTV cameras, all CCTV cameras require an optical lens. The task of the lens is to limit and focus light on the image sensor of the CCTV cameras. A lens can automatically control the amount of light reaching the image sensor, these lenses are called "Auto Iris (AI) lenses and are generally used outdoors, where the light changes constantly throughout the day, night and in varying weather conditions.

It is also the task of the lens to control the depth of field of the image, either for a wide angle or a small corner image depending on the distance of the object in question from the CCTV camera. When moveable CCTV cameras use a zoom lens is usually fitted with different points of a guarded area can be viewed. Zoom lenses are usually controlled by the CCTV operator.

CCTV Recording Devices

The recording device receives and stores images from the CCTV camera, previously the time elapsed video multiplexers and VCRs were widely used in CCTV systems, but due to developments in the technology of digital video recorders are now more commonly used.

Time lapse VCR CCTV cameras allow images to be recorded for any period of time 3 hours on a videotape, in lengths from 3 hours to more than 960 hours. The problem with time-lapse video recorders is that the longer they are set to record the less video information it can record per second, comparable to taking a photo of 25 per second on a picture to 4 seconds for example.

Digital video recorders computer to access the Hard disks store information to be stored and may be record for much longer depending on the size of the hard disk and the codec used. DVR combines and improves the absorption possibilities of a time lapse VCR and a multiplexer.

CCTV camera and VCR Switcher

When there is an obligation to record more than one CCTV camera and video switcher can be used, the cameras are plugged into the switcher and the switcher automatically switches the image is conducted to the monitor and the video. The disadvantage of using a switcher is that when an incident is possible that the CCTV camera image will change so that the incident is missed.

CCTV video recorder and multiplexer

A multiplexer is a device that takes multiple video images and places them on a VHS tape, using the properties of the PAL signal to include as many images from more CCTV cameras per second. The video information recorded is limited by the amount of CCTV cameras on the system and the duration of the VCR set to record.

CCTV standalone digital video recorder

A stand alone DVR is specifically Designed for the CCTV systems. It uses computer hard disks to store video information and an embedded operating system controls the functions of the DVR, this type of recording device is most commonly used with current CCTV systems. CCTV Digital video recorders have several tools to more video information to be able to be registered at the desired times, with technology such as video motion detection, this means that the images of the CCTV 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 DVR's built in a multiplexer that allows the user to create multiple images on the screen at any given time by dividing the image.

Many DVR can also be connected to a network or a modem for remote access possible.

CCTV DVR comes with a high contrast LCD display is called Media DVR.

CCTV PC Based Digital Recorder

PC-based DVR CCTV works much in the way as a stand-alone CCTV DVRs, but use of video-capture cards and additional software to perform the activities of the DVR, DVR, these types of simple be upgraded to accept additional cameras by adding more capture cards. Like the stand-alone DVRs, PC-based recorders can also be connected on the Internet for remote access to the DVR.

CCTV Network Video Server

Network Video Servers are designed for IP CCTV cameras WAN or LAN computer networks where each camera has its own unique IP address.

CCTV Monitor

There are two main types of the monitor; The analog monitor known as a CRT (Cathode Ray Tube) and the digital monitor that the usual PC monitor known as TFT (Thin Film Transistor) monitor.

There its advantages and disadvantages to both monitor, a TFT monitor is less space than a CRT monitor. A CRT monitor gives a better image of low and high resolution cameras than a TFT monitor. For high resolution camera, a TFT monitor more cost effective than using a high resolution CRT monitor.

CRT monitors are usually specially Designed for CCTV systems and come equipped with a composite Video Input BNC (Bayonet Nut link) connector. CCTV monitors are designed for long term use compared to standard TVs and catering for higher screen resolutions.

Developed in the late 1940's as a miniature version of the Type C connector, Bayonet Neil-Concelman (sometimes at false name of a British naval ship or Bayonet Nut Connector Connector). A connector widely used in the 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 connector.

Lighting CCTV

All CCTV cameras require a degree of relief to pick an image, black and white cameras generally work well in dark environments than color CCTV cameras. Infrared light can also be used with black and white CCTV cameras.

There are different types of infrared light or available are standard bulbs or LED (Light Emitting Diode) species.

Infra red light can burn frequencies in different areas, although invisible to the naked eye CCTV cameras can see the light emitted. Depending on the frequency that the IR light does depend on how the light is visible to the naked eye glow. Note that not all cameras are sensitive enough to pick up all frequencies of infra red.

Covert CCTV cameras

Hidden CCTV is the practice of using video cameras in locations that are not made clear to the persons being monitored by the specific CCTV camera coverage, but recommended that there is reasonable cause for the purpose of the covert, and that its primary objectives are clearly defined, only used for the purposes of prevention of crime and are not used for longer than intended.

Remote CCTV

Remote CCTV is the means of CCTV images via a computer network or standard telephone networks. Software is used on the local PC that access to the digital video recorder makes.

CCTV IP Camera

CCTV IP refers to Internet Protocol Closed Circuit Television; traditional CCTV systems use digital or analog cameras with analog cables that connect with a recording device such as a digital video recorder. IP CCTV cameras are designed to be plugged into any existing wired or wireless computer TCP / IP network directly or a broadband connection, so the CCTV camera can be accessed by any computer connected to the network, this includes the Internet.

Computers are used to network of CCTV cameras that store images, but with the flexibility of IP CCTV, the CCTV cameras could be located on either side of the world. Although IP CCTV cameras can be directly connected to an existing network, bandwidth is always a consideration if the data sent from the CCTV camera is probably much larger than the standard data transferred to the usual office networks that are not properly planned and can slow the entire network.

CCTV video signal

The video signal is known as the moving image information signal produced by a video camera, 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 CCTV cameras and IP CCTV cameras (Internet Protocol Closed Circuit Television) provided data uses a signal that consists of a series of computer readable still images. These CCTV cameras are generally connected directly to a computer or a computer network and accessed by software to enable live viewing, recording and playback of the video. A format for this moving video data is MPEG (Moving Pictures Experts Group).

CCTV video transmission

Video transmission is the way to the video signal from the camera to record or control device. The transmission can be transmitted by wire or by wireless radio broadcast.

The most common cable for transmission is wired RG6 coaxial cable.

Network cable is often used as a video is able to travel further along than standard coaxial twisted pair cables.

Other forms of video transfer fiber optic cables, microwave transmission and license free radio broadcast.

CCTV Resolution

Resolution refers to the number of definable portions of the horizontal image produced by a camera, recorded by video or digital video recorder and displayed on the monitor.

CCTV manufacturers call this TVL (Television Lines). Minimum of 420 ATV is recommandable.

The ATV of the analog PAL video information is closely compared with the pixels of a digital image.

VHS (Video Home System) recorders are suitable for recording a 300 lines or 240 lines monochrome image of a color image, SVHS (Super Video Home System) is capable of recording 400 lines monochrome 340 lines of picture and a color image.

The recording device should be the deciding factor in choosing the resolution of a camera as a 520 TVL camera recorded on a VHS recorder will only record 240 lines of the available 520 lines.

Digital Video Recorders (DVR) have the advantage of being able to PAL analog signal into a digital signal at different resolutions, the disadvantage is that the higher the resolution of the image set, the larger the file size of the digital image. The conversion of the analog PAL signal to a digital image is done using a codec (compressor-decompressor).

CCTV's Codec

A codec is used for an analog video signal into digital signal, either through hardware or software. Codec play an important role in the digital VCRs, they are not only used to convert the analog signal into a digital signal, but the best quality video information to produce even the smallest file size. This makes a big difference to the amount of video that can be stored on a hard drive DVR.

There are many standards CODEC, which are used for video compression you may encounter are MPEG-2, MPEG-4, JPEG 2000, AVI and H.264, H.264 is the latest codec is incorporated into the CCTV market, due to video-conferencing equipment.

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