CCTV Outline
For years closed circuit television (CCTV) systems, developed on the basis of the National Television System Committee (NTSC), which limits the image resolution is only 480 scan lines vertically. Other words, the image was created by scanning a scene from the top down to produce 480 rows of data. As you can imagine, this severely limited the quality of images of large scenes, such as a typical security control.
Particularly worrying feature of the NTSC standard, the use of interlaced scanning video. Interlaced scanning is a double process in which the "strange" lines drawn in the video field, or captured first scan, and the remaining "even number" lines are drawn, or captured during the second scan. This was done to limit the original appearance of the image "flicker" as a TV or monitor has been updated. This is no longer necessary to follow the current technology. While the resolution of interlaced scanning to produce images more static objects, it will lose up to half the resolution and bring unwanted "hair" objects, when the object is moving. This can be crippling for the control system.
Video
Security programs almost always require the video to record for longer periods and stored for retrieval. Until recently, this was achieved with standard video recording equipment to tape. These methods required frequent changes of cassette, limited ability to analyze and retrieve video data at certain times, and suffered long-term degradation of the signal recorded on magnetic tape.
A big jump in performance was achieved with the introduction of digital recording equipment at low cost in the 1990s. Both computer and independent, these devices have video signals from multiple cameras to be scanned and stored on computer hard drives. This provided several hundred hours of video data to be recorded and stored, and most importantly, allowing random access to retrieve the video segments at specific points in time, instead of running through a whole band.
Despite the improvements in digital recording, the limitation of basic standards, low-resolution, video quality is left unchanged, even low-cost, high-resolution digital cameras have become available. This was due to connect cameras and recording devices is still based on the old NTSC standard and analog technology, which does not support digital data or larger resolutions.
IP Camera Development
Beginning around 2002, the video technology industry, led by labor-saving machine vision and robotic applications, a lot of new digital imaging technologies such as LVDS, Camera Link and FireWire. All of these technologies to support high-resolution, progressive scan, digital cameras. However, most of the cut cables and cable length limitations made them impractical for long distance installations typical of video surveillance.
This has finally begun to change the data transmission of video over IP networks allowed the marriage of digital recording devices and video cameras with high resolution video for security applications.
IP or Internet Protocol is a digital standard that has been used for decades for connecting computer networks to transmit large amounts of data. As technology matures, the speed at which digital data can be transmitted, which is within the scope of that required for transmitting video images.
The development of IP-enabled video cameras has provided the following benefits to the industry's safety oversight:
• IP video surveillance cameras can offer multi-megapixel resolution and image quality HDTV at 30 frames per second.
• IP cameras use a form of "progressive" scan, scan the image up and down in one, eliminating the effect of the style described above for the interlaced NTSC video age.
• Cameras can be moved anywhere on an IP network (including wireless).
• Video, audio, and pan / tilt / zoom can be mediated by the same CAT5 cable.
• Live video can be viewed from any computer, anywhere, as the Internet, and many mobile devices.
HD CCTV
Of course, almost immediately, parallel development occurs with HDTV in the consumer market is married with security cameras and a digital interface for IP video surveillance.
High-definition video or high definition video devices most commonly refers to display resolutions of 1280 x 720 pixels (720p) or 1920 × 1080 pixels (1080i/1080p) video. HD security cameras provide excellent image quality, or near real-time video rates, and 16:9 widescreen. HDTV, video, images appear sharp and clear, and has shaped the modern screens and monitors. HD CCTV cameras are ideal for surveillance applications where maximum speed and exceptional image quality are essential.
Summing up
In just the past year, several manufacturers have introduced CCTV cameras with HD IP security market. Manufacturers such as Toshiba, Sony, Panasonic and Ganz, everyone carries a full line of HD cameras and accessories high-resolution IP. Prices have decreased rapidly and compete with older technologies, especially when considering the installation and maintenance costs, since most existing systems can use CAT5 IP network.
If you are shopping for a new security system, there is actually no reason not to think about the HD camera security system at first.
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