Comparison of analog and digital monitoring systems
Analog monitoring system
The analog monitoring system is based on the video matrix, splitter and video recorder as the core, supplemented by the analog series of other sensors.
The traditional analog CCTV monitoring system has its limitations:
First of all, the traditional video signal is an analog signal, and the transmission of the video signal usually adopts the way of transmission through the coaxial cable.
In a short distance, such as 200-300 meters, the attenuation of the video signal is very small; if it exceeds a certain distance, a video amplifier is required to amplify the video signal, usually adding a first-stage amplifier can extend the transmission distance by about 200 meters. However, if the video signal is amplified in two stages in the project, the image will be significantly distorted. In severe cases, the image will be distorted and even black horizontal stripes will appear. therefore,
The conventional video surveillance system is only suitable for use in a building or within a certain range.
Second, the analog monitoring system can only transmit one video signal on one coaxial cable. If data signals need to be transmitted,
Control signals or audio signals must be laid separately. At the same time, as the monitoring points and monitored points change and increase,
Cables must be laid separately, which is expensive. Moreover, the image quality of analog monitoring when performing long-delay recording is poor, which is not conducive to retrieval.
Third, the advantage of the analog monitoring system is that the image quality is maintained very well within a certain distance, while long-distance, high-definition,
The most economical and feasible way to transmit multiple video and audio signals simultaneously is to digitize the analog signal and compress and encode it.
Use public or private communication lines for transmission.
Fourth, to distinguish from the type of transmission device, the transmission of video image signals can be divided into two types of special transmission equipment and computer network transmission. The former includes video transmission equipment connected to dedicated lines or public communication lines, including coaxial cables, telephone lines or optical fibers, dedicated video image transmitters and image receivers, microwave and satellite communication equipment, etc. This method is in the seventies At the end of the decade,
It was developed in the early 1980s; the latter is to transmit video images through the existing widely distributed computer network and digital multimedia technology. This method is currently developing rapidly with the rapid popularization of Internet technology in the world. ,
This method will also become a standard for future video surveillance systems.
Finally, wired analog video signals can only use special mechanical recorders and magnetic tapes. These devices require professional repair and maintenance. The number of tapes used is limited, and the storage period is short, easy to magnetize, deform, and mold. One year of data storage,
Inquiry and editing are extremely space-consuming and time-consuming, and long-term use will bring a heavy burden to customers, and it is very cumbersome to query and obtain evidence.
Digital monitoring system
First of all, compared with analog monitoring, the technical advantages of digital monitoring are obvious. As a high-tech product that applies computer digital video compression and transmission technology to the field of image monitoring, the working principle of digital monitoring equipment is: the computer converts the analog video signal into digital information to complete the collection, browsing and transmission of video information , Storage and playback functions, and the computer can also accept various alarm information,
Output relay control information and automatically execute various alarm linkage operations according to pre-programmed procedures. The digital monitoring system performs unified management of the video surveillance, pan-tilt control, image movement detection, alarm signal input, relay control signal output, and alarm linkage operation, and has a good human-computer interaction interface. Digital monitoring also supports PSTN, ISDN, DDN, microwave and internal LAN access. Any workstation in the network can be authorized to become a sub-control station to achieve multi-level sub-control, which effectively improves the comprehensive handling capacity for emergencies. Secondly, the monitoring system uses computer intelligent management to make the alarm layout more reasonable. The computer has done security work in an orderly manner, avoiding any omissions. Based on the full use of multimedia features, combined with real-time capture, video alarm and other technologies, the prevention work is safer and more thorough, and it has a huge deterrent power for criminals. , Can prevent crime more effectively. Strict computer monitoring tracks and records every incident in real time, which is easy to obtain evidence and can effectively fight crime.
Finally, the use of digital monitoring systems can reduce the intensity of security. The security work may seem simple, but it is tedious and arduous, and the responsibility is heavy.
The highly intelligent digital monitoring system further relieves security personnel from boring and odorless work, while improving safety and reducing the intensity of work; powerful network functions, eliminating the effort of leading security checks; combined with advanced programming theory,
A good and friendly operation interface is more conducive to man-machine cooperation in monitoring and improving safety.
Performance comparison between digital monitoring system and analog monitoring system. Table 1 shows the comparison between traditional analog monitoring system and digital monitoring system. The advantages of the latter can be clearly seen from the data in the table. Digital surveillance is the latest and most leading product in the world today. It makes the surveillance field a big step from analog to digital. This is an irreversible trend and a revolutionary leap in surveillance.
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