Analysis of common faults in the diversified development of video surveillance technology and scope

    Video surveillance is the most important module in the security industry. It is more widely used than other sectors, but it has also developed from single to double, from few to many. As the scope of use and product technology of video surveillance develops to wider and broader fields, the common problems of video surveillance have also become a concern of users. To this end, experienced experts answer for us.
　　
　　Multiple development of the scope of video surveillance application
　　
　　At the same time, we also noticed that the traditional video surveillance business has a very narrow scope in terms of geographical coverage and user group coverage. This year, the development of video surveillance presents some characteristics different from the past, gradually extending to large regions and multiple fields, and the scope of application is broader and more comprehensive.
　　
　　1. From individual industries to multiple fields
　　
　　In the past, China's video surveillance applications were mainly concentrated in government departments and special departments and industries such as finance, public security, transportation, and electricity. Among them, government departments and financial industries accounted for 20.9% and 20.6% of the market share respectively. However, with the advancement of social informatization, the demand for video surveillance in more and more industries and fields has increased significantly. Even traditional users such as public security have put forward new patterns and functional requirements for urban monitoring in terms of "safe cities". This year, video surveillance has begun to extend from individual fields such as banking and transportation to multiple fields, and from traditional security monitoring to management monitoring and production and operation monitoring.
　　
　　In addition, the situation that video surveillance is only used in the enterprise industry has gradually been broken, and public households have become a new market for video surveillance applications in 2008. In the public household market, video surveillance is mainly used for residential security and property monitoring. Users can install cameras at home and use home gateways as video servers to remotely monitor home security in real time through the Internet. Although it is still far from the full realization of digital homes, with the development of IPv6 technology and information appliance technology and the further optimization of mobile monitoring equipment, video surveillance technology is likely to be promoted in digital homes first. A domestic market research report pointed out that as individual users pay more attention to home safety, the awareness of using video surveillance systems to ensure residential safety has been significantly strengthened, and it will become an emerging market in 2008.
　　
　　2. From local monitoring to cross-province and cross-region
　　
　　monitoring The market demand for video surveillance is constantly expanding. In addition to traditional industries, the corporate and personal markets are also emerging. The application prospects of video surveillance in China's most economically active small and medium-sized enterprises and individual users have already clearly emerged. At the same time, users' requirements are getting higher and higher. The most prominent one is the requirement to realize the real-time, non-regional and unimpeded transmission of a large amount of video data, so as to achieve resource sharing and provide convenient, fast and effective services for managers and decision makers at all levels.
　　
　　Especially for some large group companies, these enterprises are cross-provincial, with branches all over the country, and the activities between branches are also very frequent. If personnel from all over the country are asked to run back and forth, it will obviously reduce work efficiency, waste corporate resources and increase operating costs. Through video surveillance, it is possible to grasp the company's situation in a timely and intuitive manner even in a different place. Therefore, these customers are also in urgent need of video surveillance systems that connect the whole province and even the whole country. Many large enterprise groups, including Haier Group, require cross-provincial and cross-regional connectivity when expanding the capacity of video dedicated networks. This shows that powerful and international enterprise groups all hope to improve efficiency and reduce costs by expanding the coverage of video surveillance systems. It can be foreseen that breaking through the limitations of local networks and realizing intra-provincial or inter-provincial networking will be an important trend in the development of video surveillance platforms in 2008.
　　
　　3. From providing access to system integration
　　
　　At present, when building video surveillance systems, telecom companies in many places only provide network channels for users, and cannot participate in terminal procurement, software installation, operation and maintenance. In this mode, users need to purchase video terminal equipment, build information management software systems by themselves, and entrust third parties to maintain systems and lines, which not only increases the difficulty of users using services, but also greatly reduces the effectiveness of video surveillance systems.
　　
　　To this end, experts pointed out that telecom operators should become experts in informatization. When carrying out video surveillance services, they should use broadband networks to network scattered and independent image acquisition points, realize unified monitoring, unified storage, and unified management across regions and the world, and integrate and utilize industry resources; they should not only provide channels, but also carry out system integration, and provide integrated packaged services from hardware to software, from construction to maintenance.
　　
　　Video surveillance presents five major development trends in the future
　　
　　The scope of use of video surveillance presents a different trend from the past, developing in multiple aspects and all fields. The development of video surveillance technology itself also presents five major development trends.
　　
　　First, technological innovation will eliminate small and medium-sized enterprises with backward production capacity.
　　
　　The video surveillance system will develop in the direction of "digitalization, networking, integration, and intelligence". From the current technical development trend of market products, analog cameras will be replaced by digital cameras, and digital cameras will also develop in the direction of networking, integration, and intelligence, greatly broadening the application scope of video surveillance, making the business and technology more closely connected, and the continuous improvement of the technical level of enterprises will inevitably eliminate those small and medium-sized enterprises that rely on counterfeit and pirated mainstream products.
　　
　　Second, the scale of enterprises will help improve industry standards.
　　
　　At present, the internal system of the domestic video surveillance industry is still imperfect, which brings many obstacles to the development of the industry. In addition, although the number of enterprises in the industry is huge, most of them are small and medium-sized enterprises, showing a "many but weak" situation. In addition, the lack of core technology has led to low overall added value of the industry. However, with the continuous breakthroughs in core technologies by many powerful enterprises, while further consolidating the market position and competitive advantages of enterprises, it will also promote the further improvement of industry standards formed by enterprises such as SVAC, ONVIF, and PSIA.
　　
　　Third, leading enterprises drive the integration of domestic industries with the international market.
　　
　　The research and development and production levels of domestic video surveillance products are gradually improving. More domestic enterprises will have the strength to participate in international competition, and the proportion of overseas sales will be further improved. In the meantime, domestic enterprises will compete directly with international enterprises, prompting domestic enterprises to continuously narrow the gap between themselves and international enterprises in technology, services, marketing, etc., and drive the integration of domestic industries with the international market.
　　
　　Fourth, the transformation of equipment manufacturers will optimize the business model of the industry
　　
　　. In the construction of video surveillance projects, more security needs pay more and more attention to the technical support, daily maintenance and later updates and upgrades of the system. In response to the "one-stop demand" of end users, many equipment manufacturers have turned to provide customers with overall solutions for monitoring systems, transforming from traditional equipment manufacturers to overall solution providers, and transforming their business model from supplying single equipment to a service model of system construction and operation and maintenance, further promoting the optimization and adjustment of the industrial structure.
　　
　　Fifth, intelligent analysis will greatly increase the added value of the industry
　　
　　. The intelligence of video surveillance has become the future trend of industry development. It can extract and screen videos in real time and issue early warnings in time, which has completely changed the passive state of traditional monitoring that can only "monitor" but not "control". At present, more and more technology-based enterprises in China are focusing on the development of core technologies such as digital signal processing and video analysis algorithms, which will greatly increase the added value of the video surveillance industry and improve the development bottleneck of the existing industry value enhancement.
　　
　　Experience: Common problems and solutions for video surveillance
　　
　　With the popularization and application of video surveillance, some small problems are often encountered during use. Corresponding measures should be taken to solve the problems according to different fault conditions. For this reason, we specially consulted experts with rich engineering experience to talk to us about common faults and solutions in video surveillance.
　　
　　1. Since the connection between the monitoring system and its equipment involves many lines, if it is not handled properly, especially the improper or wrong connection of the lines connected to the main equipment, there will be problems such as open circuit, short circuit, poor insulation between lines, and wrong wiring, which will lead to the performance degradation or even damage of the equipment. In this case, we should calmly analyze and troubleshoot according to the fault phenomenon to determine what kind of fault phenomenon may occur when there is a problem with the line connection. In addition, it should be noted that the connection between each system equipment and various lines should meet the requirements of long-term operation of the monitoring system.
　　
　　2. The characteristic impedance mismatch of the transmission cable may cause several vertical bars with equal spacing on the monitor screen, and the frequency of the interference signal is basically an integer multiple of the line frequency. This interference phenomenon is caused by the characteristic impedance and distribution parameters of the video cable not meeting the requirements. For this type of interference, the impedance of each device in the system should be matched as much as possible, especially when purchasing video cables, the quality of the cables should be ensured, and the cables should be sampled and tested if necessary.
　　
　　3. Parameters such as communication interface or communication protocol are not set properly. This situation often occurs between the control host and devices such as decoders or control keyboards that have communication control relationships. That is to say, the selected control host and decoder or control keyboard, etc., did not set the communication protocol and other parameters during the project installation. Therefore, the host, decoder, control keyboard, etc. should pay attention to the setting of communication protocol and other parameters during installation.
　　
　　4. Common faults of video interference.
　　
　　* A black bar or a white bar appears on the monitor screen and rolls up or down, which is the so-called 50HZ power frequency interference. This interference is mostly caused by the improper grounding of the two devices of the front end and the control center, forming a potential difference loop entering the system, and it may also be caused by the decline in the power supply performance of the equipment itself.
　　
　　* The image has snow noise. This type of interference is mainly caused by signal attenuation on the transmission line and coupling of high-frequency interference.
　　
　　* The video image has ghosting, or the image is white, the characters are jittering, or several vertical bars with equal spacing are generated on the monitor screen. This is because the characteristic impedance between the video transmission line or the equipment is not 75Ω, resulting in impedance mismatch.
　　
　　* Twill interference, beating interference, power supply interference. This interference will not drown out the normal image when it is mild, but it will distort the image and make it unwatchable when it is severe. There are many and complex reasons for its occurrence, such as poor quality of video transmission lines, especially poor shielding performance, or noise in the power supply system, or there may be a strong interference source near the system.
　　
　　* Large-area mesh interference, also known as single-frequency interference. This phenomenon is mainly caused by the short circuit or open circuit of the core wire and the shielding net of the video cable, or due to poor contact of the BNC connector.
　　
　　5. Equipment failure caused by power supply problems mainly has the following possibilities:
　　
　　* Incorrect power supply line or power supply voltage;
　　
　　* Insufficient power (or the wire diameter of a certain power supply line is enough, the voltage drop is too large, etc.);
　　
　　* Short circuit, open circuit, instantaneous overvoltage, etc. in the transmission line of the power supply system.
　　
　　It should be noted that equipment damage may occur due to power supply errors or instantaneous overvoltage. Therefore, before power supply, it is necessary to check and inspect carefully and strictly, and never take it lightly.
　　
　　6. Faults caused by short circuit or open circuit between the core wire and the shielding net of the video cable. The manifestation of this fault is the generation of deep and chaotic large-area mesh interference on the monitor, so that the image is completely destroyed and the image and synchronization signal cannot be formed. This situation often occurs on BNC connectors or other types of video connectors. That is, when this kind of fault occurs, it is often not the entire signal line that has a problem, but only on those routes with bad connectors. As long as these connectors are carefully checked one by one, they can be solved.
　　
　　7. Space radiation interference introduced by the transmission line. This interference phenomenon occurs mostly because there are strong and high-frequency space radiation sources near the transmission system, the system front end or the central control room. The solution to this situation is to have a comprehensive understanding of the surrounding environment when building the system, and then try to avoid or stay away from the radiation source; secondly, when the radiation source cannot be avoided, the front-end and central equipment should be shielded, and the transmission line pipeline should be steel pipe and well grounded.
　　
　　8. Pan-tilt failure
　　
　　Common faults of the pan-tilt are that it does not work well or cannot rotate at all after a short time of use. In addition to product quality reasons, this situation is generally caused by the following reasons:
　　
　　* The pan-tilt that only allows the camera to be installed upright is hoisted when in use. The hoisting method increases the operating load of the pan-tilt, so the transmission mechanism of the pan-tilt will be damaged or even the motor will be burned after a short time of use.
　　
　　* The total weight of the camera and its protective cover exceeds the load-bearing capacity of the pan-tilt. Especially for the PTZ used outdoors, the weight of the protective cover is often too large, and the PTZ often cannot turn (especially in the vertical direction).
　　
　　*Outdoor PTZ may fail or even be damaged due to excessively high or low ambient temperature or poor waterproof and antifreeze performance.
　　
　　*When the distance is too far, the operation keyboard cannot remotely control the camera (including the lens) and PTZ through the decoder. This is mainly because the control signal attenuates too much when the distance is too far, and the control signal received by the decoder is too weak. At this time, a relay box should be installed at a certain distance to amplify the control signal.
　　
　　9. The matrix host does not switch the image cleanly. This fault is generally manifested in the selected screen, such as superimposed interference from other images, or interference from the line synchronization signal of other images. It is caused by the poor quality of the matrix switching switch, which cannot meet the isolation requirements between images. If the RF transmission system is used, it may also be caused by excessive cross-modulation and mutual modulation of the system.
　　
　　10. The image contrast of the monitor is too small and the image is light. If this phenomenon is not a problem with the control host and the monitor itself, it is because the transmission distance is too far, causing the video transmission line to attenuate too much. In this case, line amplification and compensation devices should be added.
　　
　　11. The image clarity is not high, and some details are lost. In severe cases, color signal loss or color saturation may be too low. This is caused by excessive loss of the high-frequency end of the image signal, that is, the loss of frequency signals above 3MHz. This situation is caused by excessive attenuation of high-frequency signals due to the long transmission distance, and there is no amplification and compensation device in the middle; or because the distributed capacitance of the video transmission cable is too large; or because of the concentrated distribution of equivalent capacitance between the core wire and the shielding wire of the transmission line in the transmission link.
　　
　　12. Color distortion. This is a fault phenomenon that is easy to occur in the long-distance video baseband transmission mode. It is also mainly caused by the excessive attenuation of the high-frequency band of the signal due to the long transmission line. In this case, a compensator should be added.
　　
　　A large-scale television monitoring system that operates in conjunction with the anti-theft alarm is a system with high technical content and complex structure. Although various fault phenomena may occur, as long as the quality is strictly controlled in the selection of equipment and equipment, and the construction is strictly in accordance with standards and specifications, there will generally be no major problems. Once a problem occurs, as long as you can analyze and think calmly, you can solve the problem quickly.