[Reprinted] wireless video surveillance system for urban traffic intersections

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With the gradual economic boom, real-time monitoring of urban traffic becomes more and more important. Establishing a comprehensive traffic image management system is the goal of the traffic management department. By establishing a digital network covering major urban roads and intersections, the video surveillance system for traffic intersections is equipped with corresponding image surveillance equipment and software, which can transmit the vehicle running status at the intersections to the scheduling center in real time, monitors the running status of road vehicles. At the same time, the public security traffic management department can control road traffic according to the actual situation on the site, arrange vehicles to smooth road sections, reduce congestion, ensure smooth road traffic, and achieve intelligent urban traffic management.

User RequirementsThe video surveillance system at the intersection of cities transfers the traffic video files collected by the monitoring sites in real time to the monitoring center in a timely manner. After the system is set up, the public security department can understand the situation of various urban roads and intersections in real time, and quickly dispatch police forces to handle dangerous situations and save on police forces, to better manage and improve the traffic environment of the city. 1. Set up a video collection point at major traffic intersections in the city. The video images are digitalized and transmitted over wireless networks. 2. Establish a wireless network system covering urban areas and connect Video Surveillance Points scattered at major traffic intersections. 3. Video Image Monitoring resolution is no less than 300 lines, and the image display speed can reach 25-30 frames per second. 4. The system has good scalability. As the number of monitoring sites increases, you only need to add front-end devices and upgrade software. 5. By using the monitoring center TV wall, users can learn the traffic flow at major intersections at any time and monitor the traffic flow for 24 consecutive hours. 6. It provides monitoring, video recording, playback, transmission and backup functions. On-site video images can be stored as evidence of traffic law enforcement, such as vehicle violation handling. This system can be used in combination with the traffic violation management system to capture vehicles that violate the rules at intersections. When a vehicle is "speeding" or "running a red light", the system automatically captures the image of the vehicle, the vehicle number plate, vehicle type, color, speed, and records are stored in the database and uploaded to the traffic violation handling department for review in a timely manner. After printing, the owner's management system is notified.Features of Wireless Video Surveillance solutions for Urban Intersections Because the traffic intersection monitoring points and traffic control centers are generally far away from each other and their distribution locations are scattered, the traditional network cabling method is not only costly, but also has a long construction period, but also scalable and flexible, once the monitoring site needs to be increased or reduced, a new construction cycle will be introduced. The wireless network can connect multiple monitored points with the traffic control center, and quickly establish a wireless network link in the shortest time. A wireless bridge can support bridging between 50 kilometers or more. To ensure stable transmission of compressed video files, sufficient network bandwidth is required. Different compressed video files have different network bandwidth requirements. To achieve better video quality, network bandwidth is even more important. The standard wireless network protocol ieee802. 11A defines a network bandwidth of 54 Mbps and a valid data transmission bandwidth of 22 Mbps. The wireless link can reach a high network bandwidth of 54mbps. Shuguang Telecom's high-speed wireless bridge product based on IEEE802.11a supports 54mbps network bandwidth, can ensure the use of MPEG-4 format of digital video stream stable and reliable transmission, achieve the purpose of wireless video monitoring. The wireless video surveillance system has the following advantages and features: 1. Easy installation and construction: wireless networks are used to avoid or reduce the workload of network cabling without damaging the original environmental facilities. This architecture features a short construction period and high cost effectiveness. 2. Fast coverage: The biggest advantage of a wireless network system is its ability to achieve fast coverage. Point-to-Point wireless communication is adopted. Generally, you only need to install one or more wireless Central Station devices to establish a broadband wireless access network system covering the entire urban area. 3. high flexibility: traffic intersections in cities are characterized by wide distribution and scattered geographical locations. Wired network is not flexible, and the future development needs must be considered as much as possible. Therefore, a large number of low-utilization information points must be preset. After a wireless network is built, you can set up a wireless terminal station at any location in the wireless signal coverage area to achieve network access with high flexibility. 4. Strong Scalability: When you need to add business points, you do not need to perform large-scale network transformation. As long as you increase or decrease the wireless devices of the monitored points, you can increase or decrease the number of monitored points.System StructureThe intersection of the wireless video monitoring system consists of video information collection points, wireless transmission systems, and traffic control centers. 1. Intersection video image acquisition point Install corresponding monitoring cameras (color or black/white, fixed or movable cloud platform, fixed focus or zoom) and software systems at traffic intersections based on the specific conditions of each city. One or more surveillance cameras can be installed at each traffic intersection, and one cloud platform, protective cover, and cloud platform controller can be installed at each perimeter. Each video collection point matches one video decoder. Surveillance cameras are used to collect video signals of real-time traffic conditions on all roads in the city. They are mainly used to monitor vehicles within a certain range from traffic intersections. The cloud platform can be controlled by a computer in the control center. You can control the camera horizontal 360 degrees, vertical 90 degrees, and zoom. The video codecs are responsible for converting the analog video signal of the camera into a digital signal, compressing it at the same time, and transmitting control signals. The video codecs are built into a 10/100 M Nic and connected to wireless devices through a network cable, the monitoring information after encoding compression is collected to the traffic monitoring management center through a wireless network. The monitoring center can view the road and intersection conditions under its jurisdiction, monitoring personnel can remotely view video images and remotely control the cloud platform in real time through the LAN of the monitoring center or the Internet. To fully ensure the bandwidth of each monitoring site, the MPEG4 encoding standard is adopted, and the bandwidth usage is low. It can achieve high-quality image transmission and storage, and the transmission distance is far away, which is suitable for monitoring in the vast urban area. 2. Wireless Transmission System The wireless broadband access device uses point-to-point methods to establish a wireless broadband network that covers urban intersections. Install a wireless bridge sunet5800 (Central Station) on the central point and a Sunet5800-RU (remote station) on the remote monitoring point ). The central station shall choose the commanding heights of the city, such as the roof of a high-rise building, the top of a tower, and the top of a high mountain, so as to ensure that the signal sent from each branch point can be received as much as possible. A central point is connected to several distributed access points. Each distributed access point shares the total channel bandwidth provided by the central point in a shared manner. The total bandwidth can be allocated based on the real-time needs of the connected users. The system adopts the 802.11a protocol standard. The total bandwidth of the system is 54 Mbps, and the valid bandwidth is 22 Mbps. Each Central Station has three to five remote monitoring sites, the valid access bandwidth of each distributed access point is generally 4 Mbps. Both the remote and Central Station devices of sunet5800 provide 10/100 BaseT Ethernet interfaces. The switches, video decoders, and cameras of the monitoring center can be connected directly to the 10/100 BaseT Ethernet interface of sunet5800. 3. Traffic Control Center The monitoring center is mainly composed of video codecs, matrix TV walls, monitoring servers, and hard disk recorders. It can receive and display on-site images at intersections, video storage, retrieval, playback, backup, and recovery. The video codecs codec process the video signals collected by front-end monitoring point cameras transmitted over wireless networks and transmit them to the Monitoring and Management Center LAN Video Monitoring Server, the vswitch then transmits the information to clients of relevant departments or personnel through the internal LAN. In the center, you can view the images of multiple monitoring sites on the site through multiple Video walls. The matrix TV wall can display the images of 9/16 cameras at the same time. The control commands issued by the monitoring center for cloud platform and lens are sent to the monitoring site through wireless devices. You can use the cloud platform control device in the monitoring center to control the cloud platform, lens aperture, focal length, and change times at any point on the site; the cloud platform automatically or remotely controls the power supply, camera switch, and so on. The on-site video images are converted into digital signals stored on the DVR. This allows you to conveniently and quickly store, update, query, and back up data and provides a basis for traffic violation processing and other law enforcement work. System Configuration Because a large number of GHz spread spectrum communication products have been deployed in urban areas, the interference in the GHz band is serious, A wireless network product working in the GHz band can obtain better signal-to-noise ratio than a GHz wireless network product and establish a stable network link. Therefore, we recommend that you use a GHz product. At the same time, the 5.8 GHz product also provides a higher bandwidth (54 Mbps ). After testing, it can meet both the bandwidth needs and ensure the stability of the connection. Finally, we decided to use Shuguang Telecom's sunet5800 series 54m high-speed wireless bridge as our preferred access device. The sunet5800 series devices can work with 5 independent frequency points. For example, during the field test, too many interference occurs and video signals are interrupted, you can flexibly adjust the frequency points used to remove the interference frequency points in time to ensure the normal operation of the equipment. If the building blocks and the signal attenuation is too high, a GHz signal amplifier can be installed to increase the wireless signal strength. If the building blocks between the monitoring site and the monitoring center are invisible, to ensure the image reception effect of the monitoring center, you can also find the third point where both the monitoring site and the center are visible, transmit data by installing a wireless relay device. Equipment required for system construction: the central station uses Sunet5800-AU high-speed wireless bridge, uses OFDM technology, rate 54 Mbps, support point-to-point wireless communication; remote station uses Sunet5800-RU, uses OFDM technology, rate 54 m, supports point-to-point wireless communication. The central station uses a flat-panel sector antenna with 18 DBI gain, and the remote station uses a 24 DBI gain parabolic antenna. Other Accessories include lightning arresters, feeder, and forwarding wires. In the choice of monitoring equipment, choose Japan Panasonic Company WV-CP460, and then equipped with three variable electric lens, cloud platform. This product has the advantages of high pixel, clear image, good backlight compensation, and stable performance. The MPEG4 ace compression algorithm is used for video compression. The data size is much smaller than that of mepg1 and MPEG2, which saves disk space and is suitable for network transmission and provides users with high-speed video images, the speed of each video stream can reach 30 frames per second, providing users with smooth image effects.Selection of wireless transmission devicesSugon Telecom is a leading Broadband Wireless Access System provider in China. It is positioned to provide telecom operators and ISP service providers with superior performance, low price, and distinctive wireless communication technologies and solutions. Sunet5800 is the latest outdoor Wireless Bridge Device for sugon Telecom working in the GHz microwave band. The sunet5800 Wireless Bridge uses the OFDM technology to support non-line-of-sight transmission and has good anti-RF performance, it also features a long transmission rate and high reception sensitivity, providing a good solution for achieving high-speed and economical wireless communication between remote LAN. The sunet5800 provides a data transmission rate of 54mbps, which enables point-to-point connection between two remote LAN networks with a bandwidth of 54m. It also supports point-to-point and point-to-point wireless networking and provides remote wireless data communication, the transmission distance of a high-gain oriented antenna can reach 50 kilometers. The Wireless RF method is used to connect multiple wired local networks distributed in different locations and between different buildings, it is an ideal solution to replace expensive optical fiber cables and leased lines. The sunet5800 network management software can remotely control device parameters and monitor the working status of any device on the network, including remote statistics, interface statistics, and other system information. The software also monitors the quality of communication links between devices and remote devices. The access control management function in the software can restrict access to devices to avoid unauthorized access.