highway Road monitoring system
highway Road monitoring system
Expressway through the monitoring system along theoutside facilities (all types of detection, display device) timely, accurate, and complete collection and notice the road in front of all kinds of information, such as traffic accidents, road conditions, road users by monitoring center monitoring ( display ) equipment intuitive understanding of the operation of traffic. In the event of traffic anomalies, timely determine the accident or blocked region, and real-time corresponding guiding and rescue information.
Two, system structure
Road monitoring system is mainly on freeway mainlines, interchange, tunnel, highway sections focus on surveillance, grasps expressway traffic condition, timely detection of traffic road, vehicle, timely guide, ensure highway safety patency, the present Expressway to video signal in monitoring and management of the bottom can be divided into the following layer:
( 1) toll station: various toll stations need to monitor the local video signal. Various toll stations under the jurisdiction of the camera signal all of the local video monitoring system, toll station to all the local image monitoring and management。
( 2) monitoring center: a freeway is usually set several sections of monitoring center, respectively, on a section of monitoring and management。 Each toll station image according to the road monitoring center requires the selection of a few from the road, road monitoring center on sections in various toll stations to upload the image of unified monitoring and management
( 3) the monitoring center: Highways Management usually according to geographical area is divided into several areas of. An area of a region adjacent to or connected with the highways for the unified control and management. The expressway monitoring center according to the area control center asked to upload the image area of each section, monitoring center monitoring center to upload images to the unified control and management。
( 4) the provincial monitoring center: Provincial Expressway Administration of all the highways unified control, management and scheduling. Each area monitoring center within the jurisdiction of the video signal selecting uploaded to the center of the province, by the province center unified monitoring and management. Provincial Center, the monitoring center, monitoring center networking between the hierarchical control。 The control signal by stepwise forward form forwarded to the need to control equipment.
Three, system scheme
In the monitoring system of the expressway construction, whether the road monitoring system, or charging station monitoring system, basically can be divided into a front end camera, transmission link, the control room control / display device of three parts.
Front camera can be divided into monitoring system for road along the tunnel entrance camera, camera, video camera and charging system in tunnel toll booth camera, camera, camera toll lane toll plaza。 According to the front camera performance characteristics of different can be divided into remote-controlled camera, camera。 Remote control camera includes a camera, along the road tunnel toll plaza camera, camera, camera camera, including tunnel toll booth camera camera, toll lane。
In the transmission link selection, is the main point to point out of the way of transmission, the specific transmission medium according to the transmission distance in order to choose the single-mode optical fiber, multimode optical fiber and coaxial cable。 In the selection of optical fiber cable, also need to choose the matching Guangduan ji。
The control room control apparatus includes a video monitor control matrix, delay recorder. In addition, according to the specific demand for use, but also can increase the projection equipment, video distributor, much picture segmentation etc.
A front end camera and toll station management, as well as the toll station management to expressway monitoring center using optical image transmission mode. The reason is along the optical fiber light source is adequate, and the road traffic video requires high image quality and good real-time performance, especially the peccancy image capture and even more so, if the compressed image transmission through the network to meet the requirements. Toll booth camera and toll station management of near distance between, can use the coaxial cable or multimode optical turbulence machine transmission. Some Guangduan Ji also can be realized on the road and toll booths video, voice synchronous monitoring. For long distance interchange, high-speed road images using single-mode optical transceiver, the maximum transmission distance of 120 km。
Each toll station management image uploaded to the monitoring center can use point-to-point optical or digital node transmitter, the toll station management matrix output select several road images that are uploaded to the expressway monitoring center. Through the monitoring center can monitor matrix network control of the highway toll station and along all images.
The provincial monitoring center is generally located in the city, and with the highway distance is further, image and data transmission can only use limited fiber. Consider the transmission of video of more, can make full use of the motorway itself SDH network advantage, the image compression and transmission through the network to become a good choice.
Video surveillance system to achieve the provincial monitoring center and the lower levels of the expressway toll station management center, multistage network control. Network control mode with networking and software hardware network two, software networking through the management control center computer networking, computer software operation management by the host matrix to achieve the control requirement. In this way more easily compatible with various manufacturers of the matrix, but by the software and computer effects, stability is poor, control is not flexible, and the cost is high hardware network。
Most of the current application of cascaded matrix host system, according to the different network methods can be divided into two series : one is the serial interface cascade mode (including RS232, RS485 ); two is the interface Ethernet networking. The network system can meet the small compared to the two network system, but the capacity is not convenient. When the interconnection matrix system is more, using the serial port ( RS232 / RS485 ) networking becomes powerless。 The first serial interconnection wiring complex, must put the interconnection matrix host is independent of the laying of communication line; the second is due to the use of serial communication, communication port baud rate is relatively low, when the system needs to control the image, in response to an alarm signal is much, serial communication mode can not meet the requirements, or simply can not upload alarm signal。
Ethernet communication mode is one of the most popular and the most popular means of communication, by Ethernet host matrix to realize complete province expressway monitoring network, can make full use of existing resources, reduce the network cost, the stability of the system is greatly improved than software networking.
Beginning of the implementation of monitoring system, video monitoring is the main expressway as a relatively independent units, the video surveillance system networking is only confined to the monitoring center monitoring center, or charge ( points) - the connection between the charging station. Regardless of the level at which a control room, can be obtained by the video signal in real-time display, for all or a portion of the input video signal storage, according to the need for a certain section of the storage information playback / inspection / forensics。
Video image transmission scheme
1 analog video transmission: analog video transmission is the traditional transmission scheme。 For the video transmission distance in three, four hundred meters, are generally used for coaxial cable as the transmission medium for direct transmission; greater than the distance, analog video transmission in fiber as transmission medium, because the optical fiber bandwidth, optical signal anti-interference ability. The optical scheme can be divided again for point to point and multiple nodes.
2: digital video transmission of uncompressed digital video transmission method is also to optical fiber bandwidth resources as the guarantee, the analog signal through the analog-digital conversion device into a digital video signal, the optical fiber transmission, the destination after digital-to-analog conversion back into analog video signal. In this process, rich bandwidth resources allow one or more video images without compression for remote transmission, image quality can be guaranteed。
Video network control program
1 matrix control mode: matrix control mode as the traditional CCTV control mode, which can realize from the system configuration, the user programming, video switching, remote camera control, alarm transport and powerful management features, in the closed-circuit television monitoring system has been widely applied. In addition, the matrix also has a network interface or serial interface to achieve with the PC connection, by PC machine and supporting graphics management software to complete part of the control, image management functions.
2.PC machine control mode: in the era of rapid development of computer technology, the market also appeared many PC machine based on closed circuit television control device, it is mainly through the design and implementation of video switch matrix, control, alarm and a series of control function. In addition, with the advent of the Internet gradually building, to the realization of online video browsing, video server control function of Web was born。