What Is a DVR Surveillance System?

The monitoring system is also called closed-circuit television monitoring system (English: Closed-Circuit Television, CCTV for short). The typical monitoring system is mainly composed of five parts: front-end audio and video acquisition equipment, audio and video transmission equipment, back-end storage, control and display equipment. The back-end equipment can be further divided into central control equipment and sub-control equipment. The front and back-end devices have multiple configurations, and the connection between them (also known as the transmission system) can be achieved through coaxial cables, twisted pairs, optical fibers, microwaves, and wireless.

Front-end video acquisition system

Cameras, lenses, gimbals, smart dome cameras, etc.

Video transmission system

transmission

1. Traditional analog monitoring system <br /> The traditional analog monitoring mode is most popular when road monitoring applications are just introduced in large and medium-sized cities in China, but it has been declining in recent years. The main defects are as follows:
The laying of transmission channels is too expensive;
Because the road monitoring points and the monitoring center are usually several kilometers or even tens of kilometers away, and the video cable with an effective transmission distance of only about 300 meters is obviously unreachable, the conventional solution is to lay optical cables between the monitoring point and the monitoring center As a transmission channel, both ends of the optical cable are connected to the optical transceiver as video / optical signal conversion equipment. However, this solution is too expensive, and the laying of optical cables alone accounts for more than 80% of the total investment cost of the entire monitoring system;
The system structure is complex, the monitoring center has a lot of equipment, and the operation is cumbersome;
The system is composed of cameras, surveillance TV walls, video recorders, control matrix, screen splitter, decoder and other auxiliary equipment. Coaxial cable is used as the image transmission medium and shielded twisted pair is used as the control signal transmission medium. The equipment is numerous and the structure is complex , Poor expandability, and most of the equipment is dedicated equipment, requiring operators to have corresponding operating capabilities after training.
2. The second-generation quasi-digital video surveillance system with a hard disk recorder as its core. <br /> Compared with the traditional analog surveillance mode, the quasi-digital video surveillance system based on digital hard disk recorders is no less than a leap. In road monitoring applications, a digital hard disk video recorder is placed on the front end of the road monitoring and connected to the camera. It can perform analog / digital conversion and compression of the video source signal and record on the local hard disk. It can be uploaded to the telecommunication data network or other network channels in the city.

Eight principles for installing a video surveillance system

typical

1. Basic conditions for maintenance:
The basic maintenance conditions required for the normal equipment maintenance of the monitoring system are to achieve the "four requirements", that is, spare parts, accessories, tools and instruments. Spare Parts In general, for each system maintenance, a corresponding spare parts library must be established, which mainly stores some more important equipment, such as cameras, lenses, monitors, etc., that are not easy to repair immediately after damage. Once these devices fail, the system may not run normally and must be replaced in time. Therefore, a certain number of spare parts must be available, and the inventory of the spare parts library must be continuously updated according to the characteristics of equipment maintenance and equipment operation cycle characteristics.

Accessories The accessories are mainly the additional configuration of various discrete components and modules in the equipment, which can be prepared more, mainly used for equipment maintenance. Commonly used accessories mainly include various integrated circuit chips and various circuit discrete components required by the circuit. Other larger equipment must be equipped with certain functional modules for emergency use. In this way, after maintenance, good benefits can be produced with a small investment, saving a lot of money for equipment upgrades.

Tools and testing instruments must be equipped with common maintenance tools and inspection equipment, such as various pliers, screwdrivers, electric pens, soldering irons, tapes, multimeters, oscilloscopes, etc. , If necessary, you should also make your own such as simulated load as a test tool.

2. Some precautions in equipment maintenance: During the maintenance of the monitoring system equipment, some conditions should be prevented to make the equipment operate normally as much as possible, and the main needs to be moisture-proof, dust-proof, anti-corrosion, lightning-proof, anti-interference work.

Moisture-proof, dust-proof and anti-corrosion For various acquisition equipment of the monitoring system, since the device is directly placed in a dusty environment, it will have a direct impact on the operation of the device. It is necessary to focus on the maintenance of moisture-proof, dust-proof and anti-corrosion. jobs. If the camera is suspended from the shed for a long time, the protective cover and dust-proof glass will soon be covered with a layer of dust, carbon ash, etc., which is dirty and black, and also corrosive, which seriously affects the viewing effect and also brings equipment. Damage, so you must do a good job of dust and corrosion protection of the camera. In some places with heavy moisture, the installation position and equipment protection must be adjusted during the maintenance process to improve the equipment's moisture resistance. At the same time, dehumidification measures must be taken frequently in high-humidity areas to solve the problem of moisture resistance.

As long as people who have been engaged in the maintenance of electromechanical systems know about lightning protection and interference prevention, it is common for equipment to be struck by lightning after a thunderstorm, which causes great safety risks for the normal operation of monitoring equipment. Therefore, monitoring equipment during maintenance Attention must be paid to the issue of lightning protection. The lightning protection measures are mainly to implement a lightning protection grounding network for equipment grounding. An integrated grounding network with a ground resistance of less than 1 ohm should be prepared according to the equipotential scheme to prevent the lightning protection grounding of the weak system and the power lightning protection grounding network Mixed practices to prevent power ground grid clutter from interfering with equipment. The anti-interference principle is to adhere to the principle of separation of strong and weak electricity when wiring, separate power cables from communication cables and video cables, and strictly follow the wiring specifications of the communications and power industries. For cameras installed outdoors, the camera must be insulated from the pole and the camera is insulated from the protective cover.

3. Maintenance technical requirements and content:

CCTV monitoring system: ensure that the front-end equipment, system control function, monitoring system function, display function, record playback function, alarm linkage function, image review function, etc. work properly, ensure that the reserved interface of the video security monitoring system works properly, and ensure system time stamping The error from Beijing Standard Time is no more than 60 seconds. The equipment for CCTV monitoring system maintenance mainly includes: camera, gimbal, monitor, video matrix, hard disk video recorder, decoder, system line and other CCTV monitoring system existing equipment maintenance and maintenance of all the equipment.

Infrared alarm system: ensure that the infrared alarm function, tamper-resistant and fault alarm functions, recording and display functions, alarm response time, alarm review function, etc. work properly, ensure that the alarm sound level meets the requirements, and ensure that the alarm system reserved interfaces are normal. Infrared alarm system maintenance mainly includes: infrared radiation detector, alarm host, line maintenance.

Security comprehensive information management: to ensure that the supporting linkage between the various subsystems and systems works normally, the protection is firm, and the working environment is clean. Ensure that the earth leakage protection function, UPS backup power supply function, lightning protection grounding function, etc. are working properly, and that the transmission function is working properly. Security information management and maintenance content: maintenance of monitoring host, hard disk video recorder, monitoring system platform, and recording data. ^[2]