When building a railway video surveillance system, it is necessary to take into consideration the special factors other than the conventional monitoring application systems according to the line application characteristics and the particularity of the environment, such as the following aspects:
Wind, thunder and lightning and other natural phenomena Wind, rain, thunder, and electricity bring great challenges to outdoor cameras. Rain, snow, high temperatures, low temperatures, lightning strikes, and windy winds can cause a dramatic increase in system maintenance costs for each damage link. The project is characterized by a large span, which is often far from high mountains and sometimes high altitude operations. Once the system is opened, it will encounter many restrictions when applying for operations, resulting in increased costs. Therefore, the selection, installation, and wiring of the outdoor camera and the high quality of the camera itself are particularly important.
Long-distance camera problem High-speed rail monitoring, according to the points are mainly divided into indoor room, indoor waiting room, ticket office and outdoor plaza, platform, etc., these locations of the camera deployment is not particularly special place, but another point of more applications is Along the railway line, the long-distance camera is absolutely necessary for long-distance cameras. Long-distance cameras may need to monitor tens of meters, hundreds of meters, or even several kilometers. This means that long-range cameras may require a few kilometers of visibility. Looking at the camera is not a simple camera with a longer focal length lens. Simply speaking, when the focal length is pulled to a certain length, it is difficult for the manual keyboard to operate to locate a very distant object, that is, the microstep control function of the camera is very important. In addition, high-altitude camera, anti-jitter, night vision lighting issues need to be considered.
In the pre-precision high-speed rail monitoring, in order to quickly locate the scene or respond to the alarm, usually the client will set a plurality of preset positions for quick application calls in the future. The number of preset positions is usually not a problem. Most cameras currently support 128 or even 256 presets. Bits, but not much used in actual projects, but the accuracy of the preset position is an important indicator to examine the PTZ camera, for example, when the user set a preset position, usually after a call, some camera presets There will be an offset, so that you have to manually fine-tune again, lose the significance of the preset position itself, affect the use.
Encoder and DVR selection High-speed railway projects, encoders and DVRs are usually deployed in various site computer rooms. Therefore, encoders and DVRs need to have ultra-stable performance (embedded encoders and embedded DVRs are preferred). Networking capabilities, remote management and upgrade capabilities. Because the network system has a complex architecture, a large span, and many routes, the encoder device needs to have a local cache function. In the case of temporary network terminals, the video will not be lost. Once the network is restored, the video can be supplemented to the NVR storage. In addition, image clarity, dual stream support, two-way audio support, and the number of alarm inputs and outputs are all indicators that need to be considered.
Coding Standards Currently, the MPEG-4 coding technology and H are mainly used in railway projects. The 264 encoding technology may deploy AVS encoding in the future, and the intra-frame compression and the inter-frame compression may be used to remove the redundant information in the time and space of the video information. The delay of coding equipment shall not be greater than 300ms, the delay of each level of forwarding shall not be greater than 500ms, the delay of decoding equipment shall not be greater than 300ms, and the PTZ response delay shall not be greater than 500ms. The delay of the system front-end acquisition equipment to the user monitoring terminal shall not be More than 3s.
Wind, thunder and lightning and other natural phenomena Wind, rain, thunder, and electricity bring great challenges to outdoor cameras. Rain, snow, high temperatures, low temperatures, lightning strikes, and windy winds can cause a dramatic increase in system maintenance costs for each damage link. The project is characterized by a large span, which is often far from high mountains and sometimes high altitude operations. Once the system is opened, it will encounter many restrictions when applying for operations, resulting in increased costs. Therefore, the selection, installation, and wiring of the outdoor camera and the high quality of the camera itself are particularly important.
Long-distance camera problem High-speed rail monitoring, according to the points are mainly divided into indoor room, indoor waiting room, ticket office and outdoor plaza, platform, etc., these locations of the camera deployment is not particularly special place, but another point of more applications is Along the railway line, the long-distance camera is absolutely necessary for long-distance cameras. Long-distance cameras may need to monitor tens of meters, hundreds of meters, or even several kilometers. This means that long-range cameras may require a few kilometers of visibility. Looking at the camera is not a simple camera with a longer focal length lens. Simply speaking, when the focal length is pulled to a certain length, it is difficult for the manual keyboard to operate to locate a very distant object, that is, the microstep control function of the camera is very important. In addition, high-altitude camera, anti-jitter, night vision lighting issues need to be considered.
In the pre-precision high-speed rail monitoring, in order to quickly locate the scene or respond to the alarm, usually the client will set a plurality of preset positions for quick application calls in the future. The number of preset positions is usually not a problem. Most cameras currently support 128 or even 256 presets. Bits, but not much used in actual projects, but the accuracy of the preset position is an important indicator to examine the PTZ camera, for example, when the user set a preset position, usually after a call, some camera presets There will be an offset, so that you have to manually fine-tune again, lose the significance of the preset position itself, affect the use.
Encoder and DVR selection High-speed railway projects, encoders and DVRs are usually deployed in various site computer rooms. Therefore, encoders and DVRs need to have ultra-stable performance (embedded encoders and embedded DVRs are preferred). Networking capabilities, remote management and upgrade capabilities. Because the network system has a complex architecture, a large span, and many routes, the encoder device needs to have a local cache function. In the case of temporary network terminals, the video will not be lost. Once the network is restored, the video can be supplemented to the NVR storage. In addition, image clarity, dual stream support, two-way audio support, and the number of alarm inputs and outputs are all indicators that need to be considered.
Coding Standards Currently, the MPEG-4 coding technology and H are mainly used in railway projects. The 264 encoding technology may deploy AVS encoding in the future, and the intra-frame compression and the inter-frame compression may be used to remove the redundant information in the time and space of the video information. The delay of coding equipment shall not be greater than 300ms, the delay of each level of forwarding shall not be greater than 500ms, the delay of decoding equipment shall not be greater than 300ms, and the PTZ response delay shall not be greater than 500ms. The delay of the system front-end acquisition equipment to the user monitoring terminal shall not be More than 3s.
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