Currently,HDForVideoMonitorIndustry, more are staying in the "concept" is really the practical application of the very few, not to talk about popularity. HDVideo cameraThe biggest difference with the analog camera is a leap in picture quality.

HD Requirements

　　SecurityMonitor screen and the movie screen has very different requirements. For example, in the content, the film pay attention to good-looking, colorful, spectacular scenes; and monitoring requires real images, the object of careful attention to the police, good-looking does not look good is not important. 16:9 aspect ratio is the same domestic and foreign high-definition standard indicators, consistent with the golden section, also in line with the human eye viewing comfort. However,Security MonitoringWant is the scene, objectives concern the details of the behavior of the embodiment of 16:9 Does it meet the needs of monitoring scenarios is questionable, and so on.

WithVideo SurveillanceUniversal application, and now has become to maintain law and order to assist the public security organs cracked an effective tool for all types of illegal cases. However, the effect of video surveillance is often not satisfactory. Such as the Internet have created a hubbub before the "triad-related suicides official Wu Xiaoqing," while video surveillance has not caught this picture, which for the video surveillance industry is very embarrassing. We should have a similar impression, whether newspapers or on television before the broadcast of the crime scene surveillance video or a screenshot, always as vague as the UFO photos obfuscation. More importantly, not allow the public security organs in the shortest possible time detection, requires a lot of manpower and resources to restore the images.

Of course, now with the advent of groups of high-definition products, which has declined, but still high-definition video surveillance of a higher demand. If the opening of Wuhan-Guangzhou high-speed rail, along the need to install videoMonitoring SystemAll-weatherMonitoring, for up to 350 kilometers per hour high speed train, the railway along the perimeter security is particularly important, apparently normalCameraDifficult to meet the requirements, you must use high-definitionShotTo ensure monitoring results. According to deputy chief engineer of the Ministry of Railways, Passenger Line (High Speed Rail) Zhang Shuguang, deputy chief designer of introduction, according to China's recent high-speed rail plan, by 2012, China will build a passenger line 42, the total mileage of 13,000 km, of which 250 km per hour 5,000 km of lines with a speed of 350 km has 8,000 kilometers of lines. This is the development of high-definition monitor is a good opportunity.

With the rapid development of video surveillance technology, the user demand for video surveillance products have also been improved, more complete functional requirements, stability, and performance requirements more clear and accurate. At the same time, in shopping malls, banks and other monitoring sites to see a person's facial features? How to look at a high-speed vehicle license? Crowded bustling railway station, stadiums, squares and so on, how to quickly and accurately find targets & hellip; ...? All these issues need to address high-definition video surveillance products.

HD technology

Effect of high-definition video from HD to ensure the first information collection, without the front-end high-definition video capture, can not talk about the back end of the HD effect. WhetherRifle bolt,One machineOrNetwork Camera, Analog cameras, the principles are the same collection, only the difference between technology and devices. For HD monitoring system, front-end collection devices generally use a network camera. We know that the camera's resolution depends on the performance of light-sensitive chips, mainlyCCDAndCMOSTwo, high-definition monitor in the field, also have applied.

CCD Charge Coupled Dev English full nameice, photosensitive coupling elements. CCD digital camera can record light changes in the semiconductor, it is a semiconductor imaging device, which has high sensitivity, anti-glare, distortion, small size, long life, anti-vibration and so on. CCD better adaptability of the monitoring scenario, inIlluminationUnder the effect of performing better. CCD from the previous 1 / 4 inch to the present 1 / 3 inch, 1 / 2 inch or 2 / 3 inch, represents the continuous development of its technology, image processing chips for another match, can achieve an output resolution of 720P or 1080i .

English full name CMOS Complementary Metal-Oxide Semiconductor, complementary metal oxide semiconductor, CMOS and CCD digital cameras, like the same as in the light of changes in the semiconductor can be recorded, and as CMOS image processing in the manufacturing process and the constant breakthroughs in technology, industry on CMOS increasingly optimistic about the prospects for prediction. HDFigureThe popularity of CMOS imaging technology is a rare opportunity. Moreover, compared with CCD, CMOS manufacturing principle simpler, smaller, power consumption can be greatly reduced, all signs show that: the field of image sensors is facing a major turning point, despite the view from the current situation, CMOS and Application of CCD image sensor market is still a dividing line, but this seems increasingly blurred boundaries. Some experts predict that, with three million pixel CMOS image sensor market, the image sensor is about to enter "CMOS era." Has a high pixel CMOS certain advantages.

In addition, the camera should be able to guarantee that the amount of light and perspective into, but also a suitable aperture for focusing and imaging with the light-sensitive components, because high-definition video is usually dependent on a focusing operation. The focal length and aperture does not meet the actual demand,HD CameraAlso casting haze of confusion. Usually in one machine with a higher zoom to better reflect the effect of high-definition. Of course, the evaluation of a high-definition cameras, in addition to clarity, there are many other factors affect image quality, such as the ultra-Wide Dynamic, Auto White Balance, Auto Exposure Compensation, etc..

1,TransmissionTechnology

Monitoring system transmission technologies include baseband video transmission,Optical fiberTransmission, network transmission,MicrowaveTransmission, twisted pair balanced cable transmission and broadband transmission of the six transmission. Each transmission technology has its own characteristics, have their own application level, for a complex control systems are often based on different distance, different monitoring requirements, different transmission. The face of large HD data applications, as well as real-time requirements to solve the long-distance optical fiber transmission using video surveillance system, the best high-speed transmission solution, through the video and control signals are converted to optical signals in optical fibers. Optical transmission with low attenuation, frequency bandwidth, from electromagnetic interference, light weight, good range of benefits of confidentiality are widely used in the backbone of the national and provincial and municipal communications networks, cable networks and high-speed broadband computer network. In the video surveillance system, has become a long-distance optical fiber transmission and control of audio and video signal transmission method of choice. However, take special optical fiber transmissionDoorTechnical staff and equipment maintenance fiber welding work, another for close monitoring signal transmission is not enough economic.

For example, the definition implies the need for higher bandwidth. Generally believed, H.264 encoding D1 (720 × 576) quality of the code flow around 2M, then the calculation to 1080P, the screen size is about 5 times D1, a simple calculation, is 5 times the stream. Therefore, H.264 encoded HD 1080P screen used a bandwidth of about 10M, and D1 quality of MPEG2 quite. It can be seen, for the "HD", network transmission, and no special requirements. However, it should be pointed out that the Internet is not able to carry high-definition quality, and must be special network or fiber. Compared to analog transmission, digital high-definition video network transmission has many advantages.

Of course, since HD takes up more network bandwidth, high-definition systems, especially in the formation of several high-definition systems, road network bandwidth for the use of or should plan carefully. For example, if you use 100M Ethernet, in fact, about the same time can only hold 5 Road HD images (taking into account the characteristics of Ethernet collision listener). If the same video source with multiple users access, the bandwidth will be even greater. So for the system design, multicasting, forwarding the use of such technology is particularly important.

Second, display technology

Back-end display devices are generally divided into CRT, LCD, PDP are three. By the development of HDTV technology, high-definition monitor displays of speed very quickly.

CRT devices with its high brightness, contrast large, color reproduction is good, the image fine and other advantages, has maintained a high index, high-quality level, is the effect of three kinds of devices to watch the best. However, due to its weight, volume and other factors, CRTMonitorsGenerally used for technical monitor for the overall quality of the image the final grasp. The LCD, PDP devices as used by-point display, there is no flyback lines, with exquisite images, no flicker, the advantage of easily cause visual fatigue. Which, LCD monitors to light, energy saving features, PDP with high brightness, large size is known.

But threeMonitorThere are also pieces of their shortcomings. CRT main problem is huge in size, high power consumption, easy magnetization. The main problem is that PDP-screen processing difficulties of small size, the screen fever, there is erosion. The main problem is that LCD brightness is not high, there is delay.

Effects of large-size high-definition displays must be shown. Truly achieve the 1920 × 1080 resolution monitor, LCD 20-inch minimum size at least, PDP minimum 50-inch, CRT at least 20 inches or more.

In rail transportation, Safe City and other large image network control center, mostly using the splicing big screen. Current mosaic screen in the most mature DLP, LCD, splicing systems, but also gradually occupy the market. LCD splicing system currently has about a 2cm gap technology is not resolved, so that some limited use in high-end. Solely from the point of view clear, LCD 1080p fully meet the requirements.

Now, some new display technologies continue to bring the product upgrades, such asSonyOLEDHigh-definition screen is only 0.3mm thick, the Japanese NICT 3D Tuichu uncorrected visual display products, but also apply to the EPD and other flexible display technology will be gradually applied to a variety of display technology products and adapt the work, all aspects of life. These products are invariably the most important position on the HD, the future will have more high-definition display products to diverse, colorful markets and will also penetrate into the realm of control.

At the same time, high definition also have DVI or HDMI interface, such as digital multimedia interface.

DVI signal transmission complete with a digital format, to ensure the video source to display terminals during the transmission of data integrity, you can get faster speeds and clearer images. So, with DVI interface display terminal are digital display terminal. DVI interface, there are three, namely, DVI-Digital (DVI-D), DVI-Analog (DVI-A) and DVI-Integrated (DVI-I). The difference is that DVI-D only supports digital display equipment; and DVI-A similar to the VGA interface, analog signal transmission; and DVI-I is both digital and analog display, and can be compatible with DVI-D equipment.

DVI with HDMI interface to avoid too large, defects can not transmit audio, HDMI though its maximum speed is less than DVI (DVI up to 8Gbps, HDMI to 5Gbps, the highest-quality HDTV signal transmission needs 2Gbps), but also supports eight channel 96kHz or 192kHz single-channel digital audio transmission (supports Dolby Digital / DTS format) without using a separate audio cable. At the same time the length of its cable can reach more than 20 meters (DVI cable will affect the quality more than 8 meters). 19-pin HDMI interface, the pins and the DVI-compatible, but with a different package, you canConverterCompatible DVI interfaces. Compared with DVI interfaces, HDMI not only has higher bandwidth and higher resolution and other features, but also set the video transmission and audio transmission in a greatly simplifiedCableConnection settings. HDMI is also backward compatible to DVI, as long as an additional adapter, you can achieve the interconnection between the two. Thus, HDMI has replaced DVI in the 2007 Digital Video Interface dominance.

HD Applications

In addition to front-end high-definition video camera installation and selection is important to note, it also must have a transmission system, intermediate system and the terminal display system can be achieved with the use of the actual effect of high-definition.

The transmission system, the transmission of video images generally choose coaxialCable, Twisted pair, UTP cable (the network transmission),WirelessTransmission,CableTransmission, etc., regardless of the manner in which transfer the image to be transmitted from the front to the back end of the entire system bandwidth of each ring then> 6M, in order to guarantee high-definition images to the requirements and meet the engineering and anti-detection technology on request. Under normal circumstances coaxial cable over 150 meters and 200 meters, the image quality will be significantly decreased, due to the characteristics of coaxial cable itself caused, it must take various measures to ensure that their end is not less than the bandwidth 6M, if necessary, to give Add Video compensation amplifiers to solve the general role of the video amplifier is not. The compensation amount of indicators should ensure that high-frequency compensation, the amplitude frequency characteristics, signal to noise ratio, CMRR, differential phase distortion, color luminance delay, chroma gain and so on to make the relevant width of loss or attenuation caused by cable defect compensation, to ensure access to the system's image of high definition.

At present, due to rising copper prices, the video image using optical fiber transmission costs have been declining, in the longer transmission distance or more images, the use of optical fiber transmission after all serve multiple purposes of the program is widely used. As the large bandwidth of fiber optic cable, the attenuation of small, high anti-interference, small size and the characteristics of strong confidentiality can be good indicators to ensure the image transmission. When sending images by other means, they must ensure that channel bandwidth.

High-resolution images also have to rely on a good performance of the terminal display to the visual in front of people, so the best choice for progressive scan monitors. Because in actual use interlaced images the monitor flicker serious, it could produce visual fatigue. If the low-resolution monitor is the same reach as a whole image. Because of the clarity of the monitor when the monitor, the video channel bandwidth and the tubes of the dot pitch, be determined by distance. According to information, the channel bandwidth and the conversion between the theoretical resolution limit of about 1M/80 line, if more considering high-definition video signal when the rate of decline factors, to achieve the display 400 lines of video images, the monitor clear degree indicators should be used according to experiences of more than 600 line of machines.

In line with the use of high-definition camera, intermediate processing equipment, includingMatrix, HardVCR, VideoServerVarious videoEncoderAnd so must meet the requirements of bandwidth and image compression, high-definition video camera to make full use of its inherent role. Use of high-definition video camera alone while neglecting otherSupportingEquipment used is not up to the real purpose.