What is CCTV CAMERA?

Video surveillance systems provide a forever open eye to watch over property, allowing a sense of safety and security. Cameras attached to a closed circuit television (CCTV) system send data to a computer or video recorder for live viewing or later playback. The term closed circuit means that the images or video recorded by the cameras are not broadcast, but saved on a storage device. Marie Van Brittan Brown firstly invented the CCTV  camera.

Video cameras`

How to tell the difference between analogue and digital cameras depend on the basis of sending analogue or digital signals to a storage device. In a less technical way, an analog camera is one that uses film rather than some type of electronic sensor, such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor chip (CMOS).

Analogue

Video tape recorder can record analogue signals as pictures directly. If we use tape to record the analogue signals, the tape must run very slowly to keep continuous operation. This is because in order to allow a three hour tape to run for 24 hours, it must be set to run on a time lapse basis which is usually about four frames a second.

Analog refers to devices in which measurable output quantities, such as voltage or pressure, represent input data. Let us take a microphone for voice recording for example. As you speak, fluctuations in air pressure strike the diaphragm of the microphone, causing corresponding fluctuations in voltage in an electrical circuit. The voltage is an "analog" of the sound waves that make up your voice.

Digital

As shown above, these cameras use a digital signal which can be saved directly to a computer. "Digital" describes the process by which a signal, such as the light reflected from a scene, is broken into the binary format so it represents the scene as a series of ones and zeros. That data is then transferred to a storage device and reassembled into a representation of the original scene. The merit of digital is that it have error correction mechanism which can correct any errors that occur during the data transfer.

As analogue circuits produce continuous, fluctuating signals, they are more sensitive to noise or distortion. With analogue, a small change in the signal can result in a significant change in the output, lots of information is lost in the process. However, digital signals deal with only one of two values at any given point in the signal chain, are much more tolerance to noise.

network

A network camera records images and sends the compressed versions over the network, also called an IP camera. Network cameras used in surveillance systems usually offer a interface so the camera can be remotely accessed and viewed over the Internet. The network camera was pioneered in 1996 by Axis Communications, the worldwide leader in the field. because network cameras are embedded devices, resolutions are higher than CCTV analogue cameras. A typical analogue CCTV camera has a PAL (768×576 pixels) or NTSC (720×480 pixels), whereas network cameras may have VGA (640×480 pixels), SVGA (800×600 pixels) or quad-VGA (1280×960 pixels), "megapixel" resolutions. Network cameras are a good surveillance solution requiring one network camera, some Ethernet cabling, and one PC.