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, tripod head, protective cover, decoder, BSV LCD splicing screen, digital scanner, warning light, alarm and other equipment (the use of equipment 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. This 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. An electronic fence was installed outside the building. Electronic fence is the most advanced perimeter anti-theft alarm system at present, which consists of high-voltage electronic pulse host and front-end detection fence. The high-voltage electronic pulse host generates and receives high-voltage pulse signals, which can generate alarm signals when the front-end detection fence is in the state of touching the net, short circuit and open circuit, and send intrusion signals to the security alarm center; The front-end detection fence is a tangible perimeter composed of rods and metal wires. Electronic fence is an active intrusion prevention fence, which can resist intrusion attempts, repel intruders, delay the invasion time, and not threaten people's life safety. It sends intrusion signals to the monitoring equipment of the security department to ensure that managers can know the situation in the alarm area in time and deal with it quickly.

System power supply:

Power supply plays an important role in ensuring 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.

Characteristics of safety monitoring system

1. Safety monitoring system: platform as the core and network as the link.

The scale and planning of the current security monitoring system are a bit daunting, or the users are a bit daunting. How to configure and manage a large number of monitoring images, coding and decoding equipment and servers collected by cameras? The management problems in large-scale monitoring system cannot be solved by manpower, so it is very urgent to build a management platform. A good management platform can manage all cameras, alarm points, codecs and background servers, so that the whole security monitoring system and security protection system can run smoothly. It is necessary to manage the whole monitoring system with the platform as the core, and enough bandwidth is needed to connect these devices and servers. Without the internet, everything is empty talk.

Second, network monitoring: many different devices are connected to each other.

Due to the historical situation of security monitoring system (mainly independent small-scale application), there are many manufacturers of security monitoring equipment, and each manufacturer has its own set of coding and decoding and network transmission practices. However, because of this situation, it is required that the large-scale monitoring system platform can access the equipment of many manufacturers. One is to protect the original investment of users; When building a new system, both users reduce investment and provide solutions. The large-scale monitoring system under construction has made a lot of efforts in this regard, and all of them have access to the video codec equipment of mainstream domestic manufacturers, which basically realizes the transparency of the equipment at the user end.

Common faults of monitoring system and their solutions

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. Faults caused by poor wiring

Because some devices (such as three-variable lens and camera of Yuntai) are connected a lot, if they are not handled well, especially the lines connected to the devices, 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. Incorrect connection output failed

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 solutions to the above problems.

First, the signal of the alarm probe is correspondingly connected with the screen splitter or the video switching host through the special alarm interface box.

Second, when there is no alarm interface box, we can design and process signal expansion equipment or driving equipment ourselves.