CCTV Camera Technician Course in Buner
Analog and digital systems work quite differently but modern CCTV networks use conversion software and hardware to convert analog to digital. This process is called retrofitting.
A traditional CCTV system comprises:
One or more cameras (analog or digital), each with a lens equipped with an image sensor
A recorder – Either a standard video tape recorder for analog systems, or a Direct Video Recorder (DVR) or Network Video Recorder (NVR) for digital systems
Cables – Either RJ45 for digital or coaxial for analog
One or more monitors to which the images are transmitted
Types of CCTV systems
Analog - Use Bayonet Neill-Concelman (BNC) connectors on coaxial cables to transmit continuous video signals. They are relatively low resolution but cheap and effective. There are more peripherals in an analog system, e.g. standard coaxial cables don’t usually transmit audio. Analog signals can be digitized, making it more cost-effective to go digital even with older equipment. The images require a video capture card and can be stored on a PC or tape recorder. A step up, analog HD enables increased resolution over traditional systems (1080 pixels) and are backwards compatible with analog cameras and BNC.
Digital – Digitalize signals at camera level. These systems don’t require a video capture card as images are stored directly to a computer but require a (relatively) large amount of space to store recordings, so they are usually heavily compressed.
Network or IP – Used with analog or digital cameras, these systems utilize a video server to stream footage over the internet. The advantages are the possibility of WiFi and audio, Distributed Artificial Intelligence (DAI) for analyzing image footage, remote access, Power Over Ethernet (POE), and better resolution. Furthermore, IP cameras have the ability to contain more cameras in one, which can cover a wide angle that may normally take multiple cameras or camera systems to cover.
ideo encoders allows for the migration of analog CCTV systems to some network systems, enabling users to take advantage of cheaper hardware and modern features. The software allows a wired connection and then digitalizes video signals, sending them to a wired or wireless IP-based system.Cameras use different types of image sensors, which convert light into electronic signals. A sensor comprises multiple photodiodes, or pixels, which register the amount of exposed light and converts it to electrons. The two most popular formats are CMOS (complementary metal oxide semiconductor) and CCD (charged coupled device).
CMOS – These are more cost-effective than CCD sensors. Megapixel (utilizing millions of pixels) CMOS sensors may even rival the quality of CCD sensors.
CCD – These are more costly with a higher power consumption. CCD scanners are generally the best option for inclement light conditions (they have higher light sensitivity) and they are quieter than CMOS. (While the signal itself is analog, it is converted for transmission by an analog-to-digital converter, which turns the pixels’ values into numeric valuesFor digital CCTV, CCD sensors generally use an interlaced scanning method (instant exposure) while CMOS and CCD can use either progressive or interlaced scanning. Analog cameras only use interlaced scanning.
Interlaced (popular for CCD applications) – This technique involves the transmission of odd and even TVLs (l stands for lines) from an image. Cameras with more than 400 lines provide good resolution and more than 700 lines is considered high resolution. These transmissions are repeatedly refreshed, reducing bandwidth and fooling the human brain into believing they are seeing a single, complete picture. That is as long as an interlaced recording is viewed on an interlaced monitor; on a progressive scan monitor, an interlaced image may look jagged. Modern video software will first de-interlace interlaced scans to convert them to progressive scans that can be viewed on analog and progressive scan monitors.
Progressive (popular for CMOS applications) – This method does not divide the image into fields (odd and even lines). Instead, the image is scanned and each line (field) is exposed on a monitor sequentially.
CCTV Camera Technician Course in Buner
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