Frequently asked questions about video surveillance technology
Video surveillance is the most important module in the security industry. Its popularity and application are much more than other sectors, but it is also developed from single to double, from less to more. With the use of video surveillance and the development of product technology in a wider and wider field, the common problems of video surveillance that have been used for load bearing have also become issues of concern to users. To this end, experienced experts answer our questions.
Multiple developments in video surveillance applications
At the same time, we also noticed that the traditional video surveillance business is very narrow in terms of geographic coverage and user group coverage, and the development of video surveillance this year has shown some different characteristics from the past, gradually extending to large areas and multiple areas. , 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 power. Among them, the government sector and the financial industry 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 substantially. Even traditional users like the public security have put forward a new pattern and functional requirements for urban surveillance in the "safe city" . This year, video surveillance has begun to extend from individual areas such as banking and transportation to multiple areas, from traditional security surveillance to management surveillance and production and operation surveillance.
In addition, the situation that video surveillance is only used in the enterprise industry has gradually been broken, and public households have also become a new market for video surveillance applications in 2008. In the public home market, video surveillance is mainly used for residential security and property monitoring. Users can install a camera at home and use a home gateway as a video server, and users can remotely monitor home security in real time through the Internet. Although it is still far from the full realization of the digital home, with the development of IPv6 technology and information appliance technology, and the further optimization of mobile surveillance equipment, video surveillance technology is likely to be first promoted in the digital home. A domestic market research report pointed out that with the increasing importance of individual users on home security, the awareness of using video surveillance systems to protect residential security has been significantly strengthened and will become an emerging market in 2008.
2. From local monitoring to inter-provincial and inter-regional
The demand market for video surveillance continues to expand. In addition to traditional industries, corporate and personal markets are also emerging. The most active SMEs and individual users in the Chinese economy have clearly shown their application prospects for video surveillance. At the same time, the requirements of users are getting higher and higher, the most prominent of which is the real-time, non-regional and unhindered transmission of large amounts of video data, so as to achieve resource sharing and provide convenient and fast for managers and decision makers at all levels , Effective service.
Especially for some large group companies, these enterprises are inter-provincial, with branches all over the country, and activities between branches are also very frequent. If you let people from all over to go back and forth, obviously reduce work efficiency and waste Enterprise resources have increased operating costs. And through video surveillance, you can realize the company's situation in a remote and timely and intuitive way, so these customers are also very urgent to connect the video surveillance system in the whole province and even the whole country. Many large enterprise groups, including Haier Group, are required to be able to connect across provinces and regions when expanding video private networks, which shows that powerful and international enterprise groups all hope to increase the coverage of video surveillance systems to improve Efficiency and cost reduction. It is foreseeable that breaking through the limitations of the local network and achieving intra-provincial or cross-provincial networking will be an important trend in the development of video surveillance platforms in 2008.
3ï¹’ From providing access to system integration
At present, many local telecommunications companies only provide network channels for users when constructing video surveillance systems, and cannot participate in terminal procurement, software installation, and operation and maintenance. In this mode, users need to purchase video terminal equipment by themselves, build information management software systems by themselves, and entrust third parties to maintain the system and lines. This not only increases the difficulty for users to use services, but also makes the video surveillance system more efficient. Greatly reduced.
To this end, experts pointed out that telecom operators must become informatization experts. When conducting video surveillance services, they should use broadband networks to network decentralized and independent image collection points to achieve unified surveillance and unification across regions and the world. Storage, unified management, integrated use of industry resources; not only provide channels, but also system integration, should provide integrated packaged services from hardware to software, from construction to maintenance.
Video surveillance shows five major development trends in the future
The use scope of video surveillance presents different trends in the past, and develops in many aspects and in all fields. The development of video surveillance technology itself also presents five major development trends.
First, technological innovation will eliminate SMEs with backward production capacity
The video surveillance system will develop in the direction of "digitalization, networking, integration, and intelligence". From the perspective of the current technology development trend of market products, analog cameras will be replaced by digital cameras, and digital cameras will also be networked and integrated. , Intelligent development, greatly expanding the scope of video surveillance applications, making business and technology closer, and the continuous improvement of enterprise technology level, will inevitably eliminate those small and medium-sized enterprises that rely on counterfeit and pirated mainstream products.
Second, enterprise scale will help improve industry standards
At present, the internal system of the domestic video surveillance industry is not perfect, which brings many resistances to the development of the industry. In addition, although the number of enterprises in the industry is huge, most of them belong to small and medium-sized enterprises, presenting the status of "more and weaker", and the lack of core technology, resulting in low added value of the industry as a whole. However, as many powerful companies continue to make breakthroughs in core technologies to further consolidate their market position and competitive advantage, they will also promote the further improvement of industry standards formed by voluntary organizations such as SVAC, ONVIF, and PSIA.
Third, leading enterprises drive the domestic industry to connect with the international market
The domestic video surveillance product R & D and production levels are improving day by day, 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 companies will compete directly with international companies, prompting domestic companies to continue to narrow the gap between themselves and international companies in terms of technology, services, marketing, etc., and driving domestic industries to integrate with the international market.
Fourth, the transformation of equipment manufacturers will optimize the industrial business model
In the construction of video surveillance projects, more security needs, more and more attention to the system's technical support, daily maintenance and later update and upgrade. In response to the “one-stop demand†of end users, many equipment manufacturers have turned to provide customers with a complete monitoring system solution, and have transformed from a traditional equipment manufacturer to a total solution provider. The business model has changed from supplying a single device to system construction and operation The service model further promotes the optimization and adjustment of the industrial structure.
Fifth, intelligent analysis will greatly increase the added value of the industry
The intelligentization of video surveillance has become the future trend of the development of the industry. Video can be extracted and screened in real time, and timely warnings can be issued in a timely manner, completely changing the passive state where traditional surveillance can only be "supervised" but not "controlled". 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 bottlenecks of the existing industry.
Experience talk: common problems and solutions of 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 have specially consulted experts with rich engineering experience to talk to us Talk about common faults and solutions in video surveillance.
1. Because the connection between the equipment of the monitoring system involves many lines, if the processing is not good, especially the line connected to the main equipment is improperly connected or connected incorrectly, there will be open circuit, short circuit, poor insulation between the lines, miswiring, etc. The problem of degraded or even damaged equipment performance. In this case, calmly analyze and troubleshoot according to the fault phenomenon to determine which fault phenomenon may occur when there is a problem with the line connection. In addition, it should be noted that the connection of various 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 bar interferences 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 fact that the characteristic impedance and distribution parameters of the video cable do not meet the requirements. For such interference, the impedance of each device in the system should be matched as much as possible, especially when purchasing video cables, to ensure the quality of the cable, and if necessary, the cable should be sampled and tested.
3. The parameters such as the communication interface or the communication protocol are not set properly. This situation often occurs between the control host and the device with a communication control relationship such as a decoder or a control keyboard. That is to say, the selected control host and decoder or control keyboard, etc., are not caused by the communication protocol and other parameters set during project installation, so the host, decoder, control keyboard, etc. should pay attention to the communication protocol and other parameters during installation Settings.
4. Common faults of video interference.
* A black bar or white bar appears on the screen of the monitor, and scrolls up or down, which is the so-called 50HZ power frequency interference. This kind of interference is mostly caused by improper grounding of the front end and the control center to form a potential difference loop and enter the system. It may also be caused by the degradation of the power supply performance of the device itself.
* The image has snowflake 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 whitish, the characters are jittery, or there are several vertical bars with equal spacing on the screen of the monitor. This is because the characteristic impedance between the video transmission line or the device is not 75Ω, resulting in impedance mismatch.
* Twill interference, beating interference, power interference. This kind of interference will not overwhelm the normal image when it is slight, but it makes the image distorted and cannot be viewed when it is severe. The reasons for this are many and complicated. For example, the quality of the video transmission line is not good, especially the shielding performance is poor, or the power supply system has clutter, or it may be due to a strong interference source near the system.
* Large area interference, also known as single frequency interference. This phenomenon is mainly due to the failure caused by the short circuit or disconnection of the core wire of the video cable and the shielding network, or the poor contact of the BNC connector.
5. The equipment failure caused by the power supply problem mainly has the following possibilities:
* The power supply line or power supply voltage is incorrect;
* The power is not enough (or the diameter of a certain power supply line is enough, the voltage drop is too large, etc.);
* The transmission line of the power supply system has short circuit, open circuit, instantaneous overvoltage, etc.
It should be noted that equipment damage may occur due to power supply errors or transient overvoltage. Therefore, before power is supplied, check and inspection must be carried out carefully and strictly, and must not be taken lightly.
6. Failure caused by short circuit or open circuit of the core wire of the video cable and the shielding network. The manifestation of this kind of failure is a large area of ​​deep and chaotic 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 such a fault occurs, it is not always a problem of the entire signal line, but only appears on the number of bad connectors. As long as you carefully check these connectors one by one, you can solve them.
7. Space radiation interference introduced by the transmission line. This interference occurs mostly because there are strong and high-frequency spatial radiation sources near the transmission system, system front end, or near the central control room. The first solution to this situation is to achieve a comprehensive understanding of the surrounding environment when constructing the system, and then try to avoid or stay away from the radiation source; secondly, when the radiation source cannot be avoided, strengthen the shielding of the front-end and central equipment. The pipeline of the transmission line is made of steel pipe and well grounded.
8. Failure of the gimbal
The common faults of the gimbal are often not working or can not rotate at all soon. In addition to product quality reasons, this situation is generally caused by the following reasons:
* Only the pan-tilt head of the camera is allowed to be installed. The hoisting method causes the gimbal's operating load to increase, so it will soon cause damage to the gimbal's transmission mechanism and even burn the motor.
* The total weight of the camera and its protective cover exceeds the load bearing of the gimbal. Especially for the gimbal used outdoors, the weight of the protective cover is often too large, and the problem that the gimbal cannot rotate (especially in the vertical direction) often occurs.
* The outdoor gimbal will malfunction or even be damaged due to poor ambient temperature, poor performance such as waterproof and anti-freeze.
* When the distance is too far, the operation keyboard cannot remotely control the camera (including the lens) and the gimbal through the decoder. This is mainly because the control signal attenuation is too large 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 clean the image switching. This kind of failure is usually manifested in the selected picture, such as the superimposition of other picture interference, or the interference of the line synchronization signal of other images. It is caused by the poor quality of the matrix switch and the requirement of isolation between images. If a radio frequency transmission system is used, it may also be caused by excessive crosstalk modulation and intermodulation 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 of the control host and the monitor itself, or the transmission distance is too far, the video transmission line is too attenuated. In this case, a device for line amplification and compensation should be added.
11. The image clarity is not high, the details are lost, and in serious cases, the color signal may be lost or the color saturation is too small. This is caused by the loss of the high frequency end of the image signal, that is, the loss of the frequency signal above 3MHz. In this case, the high-frequency signal attenuation is too large due to the long transmission distance, and there is no amplification compensation device in the middle; or the distributed capacitance of the video transmission cable is too large; or the transmission line appears between the core line of the transmission line and the shielded line Centrally distributed equivalent capacitance.
12. The color tone is distorted. This is a failure phenomenon that is easy to occur in the long-distance video baseband transmission mode. It is also mainly caused by the transmission line being too long, which causes excessive attenuation of the high frequency band of the signal. In this case, a compensator should be added.
A large-scale TV monitoring system that operates in conjunction with anti-theft alarms is a highly technical and complex system. Although various faults may occur, as long as the quality of the equipment and equipment is selected and the construction is strictly in accordance with the standards and specifications, there will generally be no major problems. Once a problem arises, as long as you calmly analyze and think, you can solve the problem quickly.
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