Because water conservancy monitoring points such as reservoir dams are distributed over a relatively wide range and are far away from the monitoring center, using traditional wired connections, the cost of line laying is high, and the construction period is long, and sometimes it is hindered by mountains and rivers. It is difficult to set up cables, so the wireless transmission method is favored in the monitoring system of the water conservancy industry. The existing wireless networks mainly include the following types:
· Satellite communications: Satellite communications, due to their high cost, need to be pre-applied, and are generally used only in military or special occasions, and are not suitable for large-scale applications in the water conservancy industry;
· Microwave data transmission: Before the 3G network is formally applied, many of the water conservancy video surveillance projects use microwave data transmission technology for video transmission, which can also meet the requirements of general monitoring. However, microwave technology requires line-of-sight transmission, which limits the terrain. Only in the open prescription can get better results;
Wireless LAN technology: Wireless LAN can meet the requirements of real-time video transmission, and can significantly increase the coverage radius through relays, etc., and can already meet the network coverage requirements of small-scale water conservancy facilities, but it still needs to be laid in medium and large-sized water conservancy facilities. With a large number of APs, the implementation and installation of projects is as easy as the connection of cables.
Wireless network transmission technology based on operators (2G or 3G and 4G systems that are being used on a small scale): Operator-based wireless network transmission mainly refers to the use of existing wireless network operator platforms for network transmission.
Under the operator's network, there are currently many methods such as GPRS/EDGE/CDMA/3G. In addition to the actual data upload speed outside the 3G mode, the speed is generally around 60-80 kbps, and the video effect is not ideal under such a bandwidth. Due to the increasing popularity and maturity of 3G networks, 3G video surveillance systems have become a hot spot for water conservancy video surveillance systems. Compared to other industries, 3G video surveillance systems are more suitable for applications in the water conservancy industry. The main reasons are as follows:
·Reservoir dams and other water monitoring sites are distributed over a wide range, far from the monitoring center, and are relatively isolated. Using traditional wired connection methods, the cost of line laying is high, the construction period is long, and even the rivers and mountains are often used. Obstacles make it difficult to set up cables; as many water conservancy facilities are in the wild and vulnerable to lightning strikes, the laying of cables, especially metal cables, should be minimized; flood prevention is a top priority for water conservancy departments, and there are more emergencies at this time. Indefinitely, there is an urgent need for video surveillance solutions that can be quickly deployed. • In the flood-fighting and rescue operations of the water conservancy industry, the dispatch of people and vehicles is a top priority. In the dispatch process, the location of people and vehicles and real-time video are key information. Wireless video surveillance of vehicles and personnel enables visualized scheduling and command.
At present, the video transmission in the 3G mode can reach an uploading speed of up to 700 Kbps, and it can generally be around 400-500 Kbps, which meets the requirements of general real-time video monitoring. This article will combine the wireless video surveillance project instance to do a brief introduction to the 3G video surveillance system, and focus on how to better meet the application characteristics of the water conservancy industry.
Demand Features of Water Conservancy Wireless Video Surveillance System
In addition to the general features of the 3G system, the video surveillance system of the water conservancy section also possesses the following industry characteristics: The equipment must meet the requirements for field use, and in particular, adequate consideration should be given to requirements such as waterproof, lightning protection, and wind resistance; support for remote control of cameras under 3G , Have better controllability, easy to command the center to carry on the overall monitoring; Use the solar energy, the wind energy and so on many kinds of power supply ways in the scene that lacks the scene to supply power; The system should reserve a plurality of serial and IO interfaces, is advantageous for other water conservancy detection systems also may Upload information through the 3G system; the annual network usage fee should be fully communicated with 3G operators such as telecommunications, and increase the flow bandwidth during the flood period to ensure better application. It is recommended that the annual traffic fee be used for settlement.
All types of wireless video encoders can be stored by hard disk, and can also be stored by FLASH. For portable and automotive applications, it is recommended to use FLASH mode for storage. Generally, 16G FLASH can meet single-channel video for more than 3 days. data.
Water Industry 3G Video Surveillance System Introduction
3G video surveillance enables video to be fully digitized and networked, enabling users to remotely monitor and centralize their management over the network, anytime, anywhere, completely resolving the limitations of geographical boundaries. The specific structure is shown in Figure 1. We have divided this system into four parts.
The monitoring point of the wireless monitoring point is composed of a camera and a wireless encoder (including an embedded 3G module). The camera is responsible for collecting video data and encoding processing by a wireless encoder. The encoded data is transmitted to the command center through 3G. This part is mainly Divided into two types of mobile monitoring points and wireless fixed-point monitoring, taking into account the integrity of the system, the wireless monitoring system can also access the original cable monitoring point.
In the transmission system, both wireless and wired transmission methods will be integrated.
Wireless mode: Adopt 3G mode for video transmission. In practical applications, it is necessary to test the local operator 3G network and select the appropriate 3G mode.
Wired mode: Wireline monitoring mainly adopts wired broadband to transmit video, and it can lease telecom or other operators' wired networks.
The command center server installs the corresponding server system and platform software in the command center to realize unified management of wireless monitoring points and cable monitoring points, and distributes data streams and video streams for the staff to monitor. The actual application system will contain multiple servers, mainly management server, video server, streaming media forwarding server and several application servers. Each application server provides several functions.
The application software staff operates and manages the system through client software, and obtains corresponding videos and other water-related information according to the user's authority to make a decision as soon as possible. At the same time, the remote command can also be issued through this system.
Features
3G video surveillance, in the water industry, can achieve real-time video surveillance, alarm, playback, events and background management and maps and other functions.
Real-time video surveillance function · Multi-screen monitoring: Real-time video window monitoring in the form of multi-screen, up to 36 screens, and supports a variety of window display mode; full-screen display: the real-time video window is displayed in full-screen mode; manual recording: manual Record video in the current window; support image capture function; can remotely control the opening of cameras such as camera rotation and lights, suitable for nighttime water conservancy monitoring, and can be directly controlled on the video screen; can directly click on the GPS track point on the electronic map to obtain real-time The floating video monitoring window realizes video surveillance in the sandbox mode and can be combined with the current water and rain system of water conservancy to provide real-time video to the water conservancy business system.
The alarm function supports anti-theft alarm, emergency alarm and water rain alarm (implemented with hydraulic database linkage); support user confirmation after the alarm function; the corresponding monitoring point or vehicle on the map when the alarm is highlighted, and automatically connect the corresponding video.
Playback function Waterproof and flood prevention vehicles equipped with GPS support track playback, video playback and track and video linked playback; support video playback drag and fast forward; support for capturing some video download and playback; provide local playback tools, suitable for a variety of video compression formats .
Event and background management event query: according to different user rights can query the corresponding event information; background management: display background management interface, background management can achieve a variety of information (such as: users, water conservancy events, permissions, etc.) effective management.
The map function supports maps in both MAPINFO and GOOGLEMAP, two maps can be freely switched in a set of systems; basic map operations such as zooming, dragging, and eagle eyes, support for scroll wheel operations; drawing of points, lines, and maps on maps, Including distance measurement, area measurement; information query, query various vehicles and monitoring point information; monitoring point management: can add monitoring point information and other business information.
Other functions · Window dual screen: Maps and video can be displayed in split screen; device IP address is displayed to obtain device network traffic statistics; IP message is used to send short messages to devices, displayed on the screen of the device, and recorded by the software platform. For reference; support chart function, the client access according to the actual scene environment; at the time of flood control to support short messages to send an emergency notification and alarm; support RFID and other access control equipment, linkage SMS or screenshot function, to further realize the small water conservancy facilities Humanized management.
3G video surveillance system key technical point equipment performance requirements
Cameras, etc. must meet the requirements of field applications for water conservancy, and have IP66 protection level; 3G video servers need to support multi-channel video coding at the same time, lightweight and easy to install and have lightning protection function; in the installation should be equipped with a waterproof chassis to further achieve water resistance, resistance Wind and other requirements.
Video Transmission Optimization in 3G Environment
The current 3G network can basically meet the real-time transmission requirements of all-way CIF images. However, 3G networks still have the problem of large network bandwidth fluctuations and many blind spots. Therefore, if the network transmission part is not specially designed, the video effect will be very unsatisfactory. In order to better carry out data transmission in the existing wireless network, currently the wireless transmission part adopts the following method to optimize in the encoder and software part.
· Analyze the wireless connection strength and status of the 3G module to obtain the real-time bandwidth of the wireless network, and adjust the video encoding parameters and stream control of the wireless video encoder accordingly; perform appropriate error correction processing on the transmitted video data packets, Adapt to the high error rate of wireless network; increase the buffer pool capacity, use the mechanism of the flow control bucket to achieve equalization of the code rate, ensure the smooth transmission and reception of data, and convert the existing code when the 3G network is converted to 2G or the momentary disconnection occurs. The stream is reduced to less than 100K, and the video buffer is refreshed appropriately to ensure real-time performance. In the 3G network recovery process, the stream is gradually increased to ensure a smooth video effect.
Recording call in 3G environment
In the 3G wireless environment, the entire video file download takes a long time because of limited bandwidth. Therefore, it is necessary to confirm the event occurrence point during downloading, and download the video file to the second in order to accelerate the download speed of the effective video. .
When the user selects a time period for video playback, the user first plays back according to the low frame rate mode, and can also use the fast forward or dragging mode to increase the playback speed. The user confirms the time when the event occurs in this mode, and then inquires according to the time. Record the video within minutes from this point in time and download a clear image containing all the frames for detailed analysis. The device supports accurate querying and recording of video files in seconds, and supports streaming media and fast-forward dragging.
Camera Control in 3G Environment
In the 3G wireless network environment, the video transmission frame rate sometimes cannot meet the real-time requirements, and the overall delay is large. When the video is transmitted to the water conservancy remote monitoring center through the 3G network, the worker will feel insufficient sensitivity to operate the camera remotely, resulting in There was a situation where the target point could not be accurately located. The camera is tightly integrated with the 3G video server and software. When the camera starts to rotate, the buffer between the videos is accelerated to improve the camera's control sensitivity. At the same time using the target control method to better achieve video surveillance.
Conclusion
The 3G video surveillance system has obtained initial application in the water conservancy industry. Since it can solve many problems that plagued video applications in the water conservancy industry, it is expected that the prospects for 3G monitoring in the water conservancy industry will be promising.
· Satellite communications: Satellite communications, due to their high cost, need to be pre-applied, and are generally used only in military or special occasions, and are not suitable for large-scale applications in the water conservancy industry;
· Microwave data transmission: Before the 3G network is formally applied, many of the water conservancy video surveillance projects use microwave data transmission technology for video transmission, which can also meet the requirements of general monitoring. However, microwave technology requires line-of-sight transmission, which limits the terrain. Only in the open prescription can get better results;
Wireless LAN technology: Wireless LAN can meet the requirements of real-time video transmission, and can significantly increase the coverage radius through relays, etc., and can already meet the network coverage requirements of small-scale water conservancy facilities, but it still needs to be laid in medium and large-sized water conservancy facilities. With a large number of APs, the implementation and installation of projects is as easy as the connection of cables.
Wireless network transmission technology based on operators (2G or 3G and 4G systems that are being used on a small scale): Operator-based wireless network transmission mainly refers to the use of existing wireless network operator platforms for network transmission.
Under the operator's network, there are currently many methods such as GPRS/EDGE/CDMA/3G. In addition to the actual data upload speed outside the 3G mode, the speed is generally around 60-80 kbps, and the video effect is not ideal under such a bandwidth. Due to the increasing popularity and maturity of 3G networks, 3G video surveillance systems have become a hot spot for water conservancy video surveillance systems. Compared to other industries, 3G video surveillance systems are more suitable for applications in the water conservancy industry. The main reasons are as follows:
·Reservoir dams and other water monitoring sites are distributed over a wide range, far from the monitoring center, and are relatively isolated. Using traditional wired connection methods, the cost of line laying is high, the construction period is long, and even the rivers and mountains are often used. Obstacles make it difficult to set up cables; as many water conservancy facilities are in the wild and vulnerable to lightning strikes, the laying of cables, especially metal cables, should be minimized; flood prevention is a top priority for water conservancy departments, and there are more emergencies at this time. Indefinitely, there is an urgent need for video surveillance solutions that can be quickly deployed. • In the flood-fighting and rescue operations of the water conservancy industry, the dispatch of people and vehicles is a top priority. In the dispatch process, the location of people and vehicles and real-time video are key information. Wireless video surveillance of vehicles and personnel enables visualized scheduling and command.
At present, the video transmission in the 3G mode can reach an uploading speed of up to 700 Kbps, and it can generally be around 400-500 Kbps, which meets the requirements of general real-time video monitoring. This article will combine the wireless video surveillance project instance to do a brief introduction to the 3G video surveillance system, and focus on how to better meet the application characteristics of the water conservancy industry.
Demand Features of Water Conservancy Wireless Video Surveillance System
In addition to the general features of the 3G system, the video surveillance system of the water conservancy section also possesses the following industry characteristics: The equipment must meet the requirements for field use, and in particular, adequate consideration should be given to requirements such as waterproof, lightning protection, and wind resistance; support for remote control of cameras under 3G , Have better controllability, easy to command the center to carry on the overall monitoring; Use the solar energy, the wind energy and so on many kinds of power supply ways in the scene that lacks the scene to supply power; The system should reserve a plurality of serial and IO interfaces, is advantageous for other water conservancy detection systems also may Upload information through the 3G system; the annual network usage fee should be fully communicated with 3G operators such as telecommunications, and increase the flow bandwidth during the flood period to ensure better application. It is recommended that the annual traffic fee be used for settlement.
All types of wireless video encoders can be stored by hard disk, and can also be stored by FLASH. For portable and automotive applications, it is recommended to use FLASH mode for storage. Generally, 16G FLASH can meet single-channel video for more than 3 days. data.
Water Industry 3G Video Surveillance System Introduction
3G video surveillance enables video to be fully digitized and networked, enabling users to remotely monitor and centralize their management over the network, anytime, anywhere, completely resolving the limitations of geographical boundaries. The specific structure is shown in Figure 1. We have divided this system into four parts.
The monitoring point of the wireless monitoring point is composed of a camera and a wireless encoder (including an embedded 3G module). The camera is responsible for collecting video data and encoding processing by a wireless encoder. The encoded data is transmitted to the command center through 3G. This part is mainly Divided into two types of mobile monitoring points and wireless fixed-point monitoring, taking into account the integrity of the system, the wireless monitoring system can also access the original cable monitoring point.
In the transmission system, both wireless and wired transmission methods will be integrated.
Wireless mode: Adopt 3G mode for video transmission. In practical applications, it is necessary to test the local operator 3G network and select the appropriate 3G mode.
Wired mode: Wireline monitoring mainly adopts wired broadband to transmit video, and it can lease telecom or other operators' wired networks.
The command center server installs the corresponding server system and platform software in the command center to realize unified management of wireless monitoring points and cable monitoring points, and distributes data streams and video streams for the staff to monitor. The actual application system will contain multiple servers, mainly management server, video server, streaming media forwarding server and several application servers. Each application server provides several functions.
The application software staff operates and manages the system through client software, and obtains corresponding videos and other water-related information according to the user's authority to make a decision as soon as possible. At the same time, the remote command can also be issued through this system.
Features
3G video surveillance, in the water industry, can achieve real-time video surveillance, alarm, playback, events and background management and maps and other functions.
Real-time video surveillance function · Multi-screen monitoring: Real-time video window monitoring in the form of multi-screen, up to 36 screens, and supports a variety of window display mode; full-screen display: the real-time video window is displayed in full-screen mode; manual recording: manual Record video in the current window; support image capture function; can remotely control the opening of cameras such as camera rotation and lights, suitable for nighttime water conservancy monitoring, and can be directly controlled on the video screen; can directly click on the GPS track point on the electronic map to obtain real-time The floating video monitoring window realizes video surveillance in the sandbox mode and can be combined with the current water and rain system of water conservancy to provide real-time video to the water conservancy business system.
The alarm function supports anti-theft alarm, emergency alarm and water rain alarm (implemented with hydraulic database linkage); support user confirmation after the alarm function; the corresponding monitoring point or vehicle on the map when the alarm is highlighted, and automatically connect the corresponding video.
Playback function Waterproof and flood prevention vehicles equipped with GPS support track playback, video playback and track and video linked playback; support video playback drag and fast forward; support for capturing some video download and playback; provide local playback tools, suitable for a variety of video compression formats .
Event and background management event query: according to different user rights can query the corresponding event information; background management: display background management interface, background management can achieve a variety of information (such as: users, water conservancy events, permissions, etc.) effective management.
The map function supports maps in both MAPINFO and GOOGLEMAP, two maps can be freely switched in a set of systems; basic map operations such as zooming, dragging, and eagle eyes, support for scroll wheel operations; drawing of points, lines, and maps on maps, Including distance measurement, area measurement; information query, query various vehicles and monitoring point information; monitoring point management: can add monitoring point information and other business information.
Other functions · Window dual screen: Maps and video can be displayed in split screen; device IP address is displayed to obtain device network traffic statistics; IP message is used to send short messages to devices, displayed on the screen of the device, and recorded by the software platform. For reference; support chart function, the client access according to the actual scene environment; at the time of flood control to support short messages to send an emergency notification and alarm; support RFID and other access control equipment, linkage SMS or screenshot function, to further realize the small water conservancy facilities Humanized management.
3G video surveillance system key technical point equipment performance requirements
Cameras, etc. must meet the requirements of field applications for water conservancy, and have IP66 protection level; 3G video servers need to support multi-channel video coding at the same time, lightweight and easy to install and have lightning protection function; in the installation should be equipped with a waterproof chassis to further achieve water resistance, resistance Wind and other requirements.
Video Transmission Optimization in 3G Environment
The current 3G network can basically meet the real-time transmission requirements of all-way CIF images. However, 3G networks still have the problem of large network bandwidth fluctuations and many blind spots. Therefore, if the network transmission part is not specially designed, the video effect will be very unsatisfactory. In order to better carry out data transmission in the existing wireless network, currently the wireless transmission part adopts the following method to optimize in the encoder and software part.
· Analyze the wireless connection strength and status of the 3G module to obtain the real-time bandwidth of the wireless network, and adjust the video encoding parameters and stream control of the wireless video encoder accordingly; perform appropriate error correction processing on the transmitted video data packets, Adapt to the high error rate of wireless network; increase the buffer pool capacity, use the mechanism of the flow control bucket to achieve equalization of the code rate, ensure the smooth transmission and reception of data, and convert the existing code when the 3G network is converted to 2G or the momentary disconnection occurs. The stream is reduced to less than 100K, and the video buffer is refreshed appropriately to ensure real-time performance. In the 3G network recovery process, the stream is gradually increased to ensure a smooth video effect.
Recording call in 3G environment
In the 3G wireless environment, the entire video file download takes a long time because of limited bandwidth. Therefore, it is necessary to confirm the event occurrence point during downloading, and download the video file to the second in order to accelerate the download speed of the effective video. .
When the user selects a time period for video playback, the user first plays back according to the low frame rate mode, and can also use the fast forward or dragging mode to increase the playback speed. The user confirms the time when the event occurs in this mode, and then inquires according to the time. Record the video within minutes from this point in time and download a clear image containing all the frames for detailed analysis. The device supports accurate querying and recording of video files in seconds, and supports streaming media and fast-forward dragging.
Camera Control in 3G Environment
In the 3G wireless network environment, the video transmission frame rate sometimes cannot meet the real-time requirements, and the overall delay is large. When the video is transmitted to the water conservancy remote monitoring center through the 3G network, the worker will feel insufficient sensitivity to operate the camera remotely, resulting in There was a situation where the target point could not be accurately located. The camera is tightly integrated with the 3G video server and software. When the camera starts to rotate, the buffer between the videos is accelerated to improve the camera's control sensitivity. At the same time using the target control method to better achieve video surveillance.
Conclusion
The 3G video surveillance system has obtained initial application in the water conservancy industry. Since it can solve many problems that plagued video applications in the water conservancy industry, it is expected that the prospects for 3G monitoring in the water conservancy industry will be promising.
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