Safety monitoring

Security monitoring system is an independent and complete system, which uses optical fiber, coaxial cable or microwave to transmit video signals in its closed loop, and forms an independent and complete system from camera shooting to image display and recording. It can reflect the monitored object in real time, vividly and truly, which not only greatly extends the observation distance of human eyes, but also expands their functions. It can replace manual monitoring for a long time in harsh environment, so that people can see the actual situation at the monitoring site and record it through a video recorder. At the same time, the alarm system equipment alarms the illegal intrusion, and the generated alarm model is input to the alarm host, which triggers the monitoring system to record.

Composition of safety monitoring system:

Front-end part: The front-end completes the shooting of analog video, the generation of detector alarm signal, the control of pan/tilt and protective cover, alarm output and other functions. It mainly includes: camera, electric zoom lens, outdoor infrared crosstalk detector, dual-display detector, temperature and humidity sensor, pan/tilt, protective cover, decoder, warning light, alarm and other equipment (equipment usage is configured according to the actual needs of users). The camera shoots the scene into an analog video electrical signal through the built-in CCD and auxiliary circuit, and transmits it through the coaxial cable. The electric zoom lens brings the shooting scene closer and farther, and realizes optical adjustment such as aperture and focus. The temperature and humidity sensor can detect the temperature and humidity in the environment, thus ensuring a good internal physical environment. The tripod head and protective cover provide a suitable working environment for the camera and lens, and the shooting angle can be adjusted horizontally and vertically. Decoder is the core equipment to control the pan/tilt and lens. Through it, the lens and pan/tilt can be controlled by software through the microcomputer interface.

Transmission part: The transmission part introduced here is mainly composed of coaxial cable. The transmission part requires real-time transmission of the image recorded by the front camera, and at the same time requires low loss and reliable transmission quality, and can clearly restore the displayed image in the video control center.

Control part: This part is the core of the security monitoring system, which completes the functions of digital acquisition of analog video monitoring signals, MPEG- 1 compression, monitoring data recording and retrieval, hard disk recording and so on. Its core unit is the acquisition and compression unit, and its channel reliability, operational processing ability and convenience of video retrieval directly affect the performance of the whole system. The control part is the key part to realize the linkage between alarm and video recording.

Television wall display part: This part completes the display of real-time monitoring signals and the playback and retrieval of video content on the system monitor or monitoring screen. The system supports multi-screen playback, simultaneous recording of all channels, alarm screen and sound prompt. It is not only compatible with the unobstructed monitoring function of the traditional TV monitoring wall, but also greatly reduces the work intensity of the personnel on duty and improves the reliability of security. In fact, the terminal display part has completed another important task-control. The control includes camera pan/tilt, lens control, alarm control, alarm notification, automatic and manual fortification, anti-theft lighting control and other functions. Users only need to click the mouse on the system desktop to operate.

Anti-theft alarm part: install active infrared probes at important entrances and exits and stairs for protection, and install alarm host in the duty room (monitoring room) of the monitoring center. Once someone enters a place, the probe will automatically sense and trigger an alarm, the host will display the alarm position, and the corresponding searchlight and camera will be linked, and the alarm camera will automatically switch to an alarm camera screen on the host. The computer in the alarm center will pop up an electronic map, make an alarm record, and prompt the personnel on duty to handle it, which greatly strengthens the security. The alarm prevention system uses active infrared mobile detectors to control important channels and connect them to the alarm center of the management center. When someone enters from an abnormal entrance during non-working hours, the detector will immediately send an alarm signal to the management center, and at the same time start the linkage device and equipment to warn the intruder, so that continuous camera shooting and video recording can be carried out.

System power supply: Power supply plays a vital role in the normal operation of the whole closed-circuit monitoring and alarm system. Once the power supply is damaged, the whole system will be paralyzed. System power supply can be divided into centralized power supply and decentralized power supply, and users can choose according to actual needs.

The above is just a typical introduction of security monitoring system. In practical application, there will be different types of schemes, and the security monitoring system scheme will generally be tailored according to the different requirements of users.

Common faults of monitoring system and their solutions

( 1)

After a monitoring system enters the debugging stage, trial operation stage and delivery, there may be some faults, such as: it can't run normally, the system can't meet the design requirements, and the overall performance and quality are not ideal, that is, some "soft faults". These problems are inevitable for a monitoring project, especially for a complex large-scale monitoring project.

1. Equipment failure caused by wrong power supply. There are several possibilities for incorrect power supply: incorrect power supply line or voltage, insufficient power (or insufficient line diameter of a power supply line, excessive voltage drop, etc.). ), short circuit, open circuit and instantaneous overvoltage in the transmission line of power supply system. In particular, equipment damage caused by power supply error or instantaneous overvoltage occurs from time to time. Therefore, in the system debugging, before the power is turned on, we must seriously and strictly check and check, and we must not take it lightly.

2. Because some devices (such as three-variable lens and camera of pan/tilt) are connected a lot, if they are not handled well, especially the lines connected to the devices are not handled well, there will be problems such as open circuit, short circuit, poor insulation between lines, wiring errors, etc., which will lead to equipment damage and performance degradation. In this case, we should calmly analyze the fault phenomenon and judge which lines in several lines have connection problems to produce that fault phenomenon. This will narrow down the problem. In particular, it is very common for cameras with pan/tilt to lose connection due to long-term omni-directional movement. Therefore, in this case, special attention should be paid to the connection of equipment and various lines to meet the requirements of long-term operation.

3. Quality problems of the equipment or components themselves. Theoretically, all kinds of equipment and components may have quality problems. However, from the experience, it is purely the quality problem of the product itself, which mostly occurs in decoders, electric pan/tilt, transmission parts and other equipment. It is worth pointing out that some equipment may not be unavailable as a whole, but some technical indicators can not meet the indicators given in the product manual. Therefore, it is necessary to carry out necessary sampling inspection on the selected products. If it is really a product quality problem, the best way is to replace the product, rather than dismantle and repair it yourself.

In addition, the most common problem is due to improper adjustment of equipment. For example, the adjustment of the camera's back intercept is a very detailed and accurate work. If not carefully adjusted, there will be problems such as poor focus or defocus during various operations of the three variable lenses. In addition, whether the positions of some switches and adjusting knobs on the camera are correct, whether they meet the technical requirements of the system, and whether the encoder switches or other adjustable parts of the decoder are set correctly will directly affect the normal use of the equipment itself or the normal performance of the whole system.

4. Problems caused by incorrect connection between devices (or components) generally appear in the following aspects:

(1) impedance mismatch.

⑵ The communication interface or communication mode does not correspond. This situation often occurs between the control host and the devices with communication control relationship such as decoder or control keyboard, which means that the selected control host and decoder or control keyboard are not the products of the same manufacturer. Therefore, the host, decoder and control keyboard should all be made by the same manufacturer.

(3) The driving capacity is insufficient or exceeds the specified number of equipment connections. For example, some splitters have alarm input interfaces, and their product manuals show that they are connected with alarm probes, long-delay video recorders and other system hosts. If the alarm probe is connected in parallel to the alarm input end of the image splitter, the alarm signal of the probe will drive the alarm host and the image splitter. In this case, the problem of insufficient driving ability often occurs. The phenomenon is that although the image splitter can give an alarm, due to the weak alarm signal and unstable operation, the image picture of the camera corresponding to the alarm signal is instantly converted into a full-screen picture on the monitor but lost (unable to be maintained), so that the image on the monitor is still a multi-picture before the alarm.

One of the ways to solve the above problems is to connect the alarm probe signal with the screen splitter or video switching host through a special alarm interface box. Second, when there is no alarm interface box, we can design and process signal expansion equipment or driving equipment ourselves.

The above problems sometimes appear in the output and distribution of video signals.

(2)

1. In video transmission, the most common fault phenomenon is that a black bar or white bar appears on the monitor screen and slowly scrolls up or down. Therefore, when analyzing this fault phenomenon, we should distinguish two different fault causes. A simple way to distinguish between power supply problems and ground loop problems is to connect only one camera without power supply problems to the control host. If the above interference phenomenon does not appear on the display, there is no problem with the control host. Next, you can connect a portable monitor to the video output end of the nearby front camera and check each camera one by one. If there is, it will be handled. If not, the interference is caused by other reasons such as grounding circuit.

2. There is wood grain interference on the monitor. The appearance of this kind of interference will not slightly drown the normal image, but in severe cases, it will be impossible to watch the image (or even destroy the synchronization). There are many complicated reasons for this failure. There are roughly the following reasons:

(1) The quality of video transmission line is not good, especially the shielding performance is poor (the shielding net is not a good copper net, or it is too thin to shield). At the same time, the line resistance of this video line is too large, which leads to a large signal attenuation and aggravates the fault. In addition, the characteristic impedance of this video cable is not 75 Ω, and the parameters are not in conformity with the specifications, which is also one of the reasons for the failure. Because the above interference phenomenon is not necessarily a fault caused by poor video lines, it is necessary to accurately and carefully judge the cause of this fault. Only by excluding other possibilities can we consider it from the perspective of bad video lines. If it is really a cable quality problem, the best way is of course to replace all these cables with cables that meet the requirements. This is the best way to solve the problem completely.

(2) The power supply of the power supply system is not "clean". The power supply here is not "clean", which means that the interference signal is superimposed on the normal power supply (50-cycle sine wave). The interference signal on the power supply mainly comes from the equipment using SCR in the power grid. Especially the SCR equipment with high current and high voltage, the pollution to the power grid is very serious, resulting in the power supply of the same power grid is not "clean". For example, there are high-power SCR frequency modulation and speed regulation devices, SCR rectifier devices, SCR AC /DC conversion devices and so on. In this power grid, it will pollute the power supply. The solution to this situation is relatively simple, as long as the whole system adopts purified power supply or online UPS power supply, it can basically be solved.

(3) There are strong interference sources near the system. This can be judged by investigation. If this is the case, the solution is to strengthen the shielding of the camera and ground the pipeline of the video line.

3. The fault caused by short circuit or open circuit between the core wire of the video cable and the shielding net. The performance of this fault is that there is deep and chaotic moire interference in a large area on the display, which destroys all the images and does not form images and synchronization signals. This often happens on BNC interfaces or other types of video interfaces. That is to say, when this kind of fault phenomenon occurs, it is often not that all signals of the whole system have problems, but only those signals with bad joints. As long as these joints are carefully examined one by one, they can be solved.

4. Fault phenomenon caused by mismatch of transmission line characteristic impedance. The performance of this phenomenon is to produce 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 is due to the characteristic resistance of the video transmission line.

Reactance is not caused by impedance mismatch caused by 75 Ω. It can also be said that this interference phenomenon is caused by the fact that the characteristic impedance and distribution parameters of video cable do not meet the requirements. The solution generally depends on the method of "series resistance at the beginning" or "parallel resistance at the end". In addition, it is worth noting that when the video transmission distance is very short (generally within150m), the above interference phenomenon may not necessarily occur when using the video cable with unmatched impedance and too large distribution parameters. The fundamental way to solve the above problems is to ensure the quality when purchasing video cables. When necessary, the cable shall be sampled and tested.

5. Space radiation interference caused by transmission lines. This interference phenomenon is mostly caused by the strong high frequency space radiation source near the transmission system, the front end of the system or the central control room. One of the ways to solve this situation is to understand the surrounding environment and try to avoid or stay away from the radiation source when the system is established; Another method is to strengthen the shielding of the front-end and central equipment when the radiation source cannot be avoided, and the transmission line is made of steel pipe and grounded.

(3)

1. Failure of Yuntai.

It is a common fault of tripod head that it doesn't work well or doesn't turn at all after being used for a long time. Apart from the factors of product quality, this situation is generally caused by the following reasons:

(1) Only cameras are allowed to be installed in Yuntai, and the lifting mode is adopted when using. In this case, the hoisting mode will lead to an increase in the operating load of the pan/tilt, so it will soon lead to the damage of the pan/tilt rotating mechanism and even burn out the motor.

(2) The total weight of the camera and its protective cover exceeds the bearing capacity of the tripod head. Especially for outdoor use, the weight of the protective cover is often too large, which often leads to the problem that the platform cannot turn (especially in the vertical direction).

(3) The outdoor Yuntai platform is out of order or even damaged due to the high or low ambient temperature and inadequate waterproof and antifreeze measures.

2. When the distance is too far, the operating keyboard can't remotely control the camera (including lens) and pan/tilt through the decoder.

This is mainly because the control signal is too attenuated when the distance is too far, and the control signal received by the decoder is too weak. At this time, it is necessary to install a relay box at a certain distance to amplify the shaping control signal.

3. The image contrast of the monitor is too small and the image is very weak.

This phenomenon is either the problem of the control host and the display itself, or the transmission distance is too long or the video transmission line is too attenuated. In this case, line amplification and compensation devices should be added.

4. The image definition is not high, and the details are lost. In severe cases, the color signal is lost or the color saturation is too small.

This is because the high-frequency loss of image signals is too large, and the signals with frequencies above 3MHz are basically lost. In this case, the transmission distance is too long, and there is no amplification compensation device in the middle; Or the distributed capacitance of the video transmission cable is too large; Or the concentrated distribution of equivalent capacitance between the core wire and the shielding wire of the transmission line in the transmission link.

5. Tone distortion.

This is a common fault phenomenon in long-distance video baseband transmission mode. The main reason is that the high frequency phase shift of the signal caused by the transmission line is too large. In this case, a phase compensator should be added.

6. There is something wrong with the keyboard.

This phenomenon can basically be determined to be caused by the "crash" of the operating keyboard when there is no problem with the connection. In the operating instructions of the keyboard, there are generally methods to solve the "crash", such as "resetting the whole machine", which can be solved by this method. If it cannot be solved, the keyboard itself may be damaged.

7. The switch from host to image is not clean.

The performance of this fault phenomenon is that the interference of other pictures or the interference of line synchronization signals of other images is superimposed on the selected picture. This is due to the poor quality of the host or matrix switch, which can not meet the requirements of isolation between mirrors.

If RF transmission system is used, it may also be caused by excessive cross modulation and mutual modulation of the system.

The large TV monitoring system associated with burglar alarm is a high-tech complex system. Although there may be various failures, as long as the quality of the selected equipment and equipment is well controlled and the construction is carried out in strict accordance with standards and specifications, there will generally be no major problems. Even if there is, as long as you calmly analyze and think, and don't blindly disassemble, you can solve the problem soon.

Safety monitoring system is a new specialty that people pay more and more attention to. As far as the current development is concerned, the application is getting wider and wider, and the scientific and technological content is getting higher and higher. Almost all high-tech can promote its development, especially the arrival of the information age, which provides an opportunity for the development of this major. However, as far as the monitoring industry is concerned, the system composition has not been clearly defined, which makes it inconvenient for engineers and users to communicate when talking about the security monitoring system.

For the security monitoring system, according to the different functions of each part of the system, we divide the whole security monitoring system into seven layers-presentation layer, control layer, processing layer, transmission layer, execution layer, support layer and acquisition layer. Of course, due to the increasing integration of devices, for some systems, some devices may exist as multiple layers at the same time.

I. Presentation layer

Performance city is our most intuitive feeling, which shows the quality of the whole security monitoring system. Such as monitoring TV wall, monitor, high-pitched alarm horn, alarm automatic connection telephone, etc. It's all on this floor.

Two. Control layer

The control layer is the core of the whole security monitoring system and the clearest embodiment of the scientific and technological level of the system. Usually we have two control methods-analog control and digital control. Analog control is an early control mode, and its console usually consists of controller or analog control matrix, which is suitable for small local security monitoring system. This control method has low cost and low failure rate. However, for medium and large security monitoring systems, this method is complicated to operate and has no price advantage. At this time, our wiser choice should be digital control. Digital control takes the industrial control computer as the control core of the monitoring system, which changes the complex analog control operation into a simple mouse click operation, shrinks the huge analog controller stack into an industrial control computer, and turns the complex and huge control cable into a serial telephone line. It makes medium and long-distance monitoring become a reality, and makes internet remote monitoring possible. However, digital control is not so perfect, and there are still problems, such as high price of control host, waste of modules, possible collapse of the whole system and lagging control.

Three. Treatment layer

Perhaps the processing layer should be called audio and video processing layer, which distributes, amplifies and divides the audio and video signals sent by the transmission layer, and organically connects the presentation layer and the control layer. Audio and video distributors, audio and video amplifiers, video splitters and audio and video switchers all belong to this floor.

Four. transport layer

The transport layer is equivalent to the blood of the security monitoring system. In the small security monitoring system, our most common transport layer devices are video cables and audio cables. For medium and long-distance monitoring systems, we often use RF cables and microwaves. For remote monitoring systems, we usually use the Internet as a cheap carrier. What is worth mentioning is the emerging transport layer medium-network cable/optical fiber. Most people have a misunderstanding about digital security monitoring. They think that the digital security monitoring system used in the control layer is the digital security monitoring system, but it is not. The transmission medium of pure digital security monitoring system must be network cable or optical fiber. When the signal comes out of the acquisition layer, it has been modulated into a digital signal. Digital signal runs on the mature network at present, which is lossless in theory, ensuring the lossless display of remote monitoring images, which is incomparable to analog transmission. Of course, high-performance returns also require high-cost investment, which is one of the most important reasons why pure digital security monitoring systems cannot be popularized.

Verb (abbreviation for verb) execution layer

The executive layer is the command object of our control instruction. In some cases, it is not well separated from the support layer and acquisition layer mentioned later. We think that the controlled object is the execution layer device. For example: pan/tilt, lens, decoder, ball, etc.

Support layer of intransitive verbs

As the name implies, the support layer is used to support the back-end equipment, protect and support the acquisition layer and the execution layer equipment. It includes support, protective cover and other auxiliary equipment.

Seven. Acquisition layer

Acquisition layer is the key factor for the quality of the whole security monitoring system, and it is also the place with the highest system cost. It includes lens, camera, alarm sensor and so on.

IDRS distributed network video centralized monitoring management system

IDRS distributed network video management system, referred to as IDRS NVMS, is a set of application software developed with IDRS series digital monitoring products and running under Microsoft Windows platform.

IDRS NVMS is a high-tech product, which aims to meet the special requirements of usability and functionality of large-scale remote monitoring system. It is based on computer, multimedia, network, video coding and decoding, communication and other technologies. It consists of a general-purpose PC and software modules, and runs on an IP network that can support both voice and data communication through mouse and keyboard operation. Through it, monitoring personnel can quickly connect different monitoring areas through the network to realize various monitoring and management functions.

IDRS NVMS adopts open system architecture and is equipped with standard hardware equipment. You can freely build a monitoring and management platform according to different needs and site conditions. The flexible and value-added solution it provides makes the general digital monitoring system far behind.

Product background: With the world entering the digital age, the demand for network remote monitoring is increasing. People hope to get more security and management needs with the help of the convenient and fast channel of network.

Modern large-scale network remote monitoring projects generally have the characteristics of many monitoring points, scattered monitoring areas and different network conditions. At the same time, it is required to establish a multi-level user management model combining centralization and decentralization in management, emphasizing simplicity and flexibility in operation and perfection in function as far as possible. However, the common network monitoring solution cannot meet the multi-task requirements at the same time, so we have formulated and provided this more advanced and professional solution.

Scope of application: large-scale monitoring projects with scattered monitoring sites need to establish centralized management mode, and monitoring projects need to integrate PC-based, embedded host and network video server. It is necessary to realize the monitoring project of multi-user, multi-department and multi-level authority control, and to simplify the network monitoring operation. The project monitoring center needs to set up a TV wall, the front-end outlets of the project that need centralized alarm management are unattended, and the projects that need centralized monitoring through the network need centralized storage and streaming media forwarding functions. Project application fields: financial industry (bank outlets, credit cooperatives, postal savings remote centralized network monitoring), public security, transportation system (urban road monitoring, highway monitoring, urban public security joint defense monitoring, "digital urban management" and "safe city" monitoring system), education system (examination room monitoring, campus security monitoring, distance teaching, etc. ) Oil fields, coal mining systems (remote centralized network monitoring of oil wells, oil pipelines and mines), telecommunications, water conservancy and electric power industries (network monitoring of computer rooms and unattended base stations), large enterprises and distance schools across provinces and cities.

[Edit this paragraph] Development Status of Security Industry

Because of the geographical advantages, the vast majority of domestic security companies are concentrated in the Pearl River Delta, of which Shenzhen is the most concentrated. Although the domestic security industry has made great progress in recent years, on the whole, small scale and low risk resistance are still the same characteristics of most security enterprises. According to statistics, at present, 23% of domestic security enterprises have sales below 6,543.8+0,000 yuan, 37% have sales of 6,543.8+0-5 million yuan, less than 40% have annual sales of more than 5 million yuan, and the number of enterprises with more than 6,543.8+0,000 yuan is even smaller, far from forming a scale advantage. In terms of personnel structure, enterprises with less than 10 account for 28%, enterprises with 10-50 account for 52%, enterprises with 50- 100 account for 10%, and enterprises with more than 100 account for/kloc- This shows the scale of the enterprise. At present, domestic security production and marketing enterprises are mainly private enterprises and joint-stock enterprises, accounting for 565,438+0% and 26% respectively. The proportions of collective enterprises, foreign-funded enterprises and state-owned enterprises are 2%, 12% and 9% respectively. Figures show that small and medium-sized enterprises, including short-term actors, have sprung up like mushrooms after rain because the threshold required by the domestic security industry is not high. This is probably the main reason why there are no "big" enterprises in the domestic security industry so far.

Application of 3G Video Monitoring Scheme in Security Monitoring

3G video surveillance is a supplement to fixed-line video surveillance, and the convergence trend of 3G mobile video surveillance solutions released this time is more obvious. It adopts high-bandwidth wireless access, supports uploading live images at any place and receiving remote images at any place, and integrates with fixed-line video monitoring system to achieve full coverage of time and place. He said that the 3G video surveillance system is not a competition with the existing fixed-line monitoring system, but a typical 3G multimedia application with high-end and differentiated characteristics, which can be widely used in emergency command, bus monitoring, home monitoring, public multimedia services and other fields, thus expanding the application environment and usage mode of video surveillance on the basis of the original monitoring system and bringing users a more friendly, convenient and personalized business experience.