With the development of economy and social progress, people are gathering more and more in public. At the same time, damaging cases of public security also bring severe challenges to harmonious society. Cameras and Surveillance system can provide real-time video monitoring and video recording functions, providing an important basis for post-evidence collection.The rapid development of Cameras and Surveillance system provides an effective means for the construction of “harmonious city”.Data collected from image collection points distributed in Cameras and Surveillance system need to be transmitted to the server in real time for viewing, analysis and summary.Data transmission access network is a difficult point in the construction of urban monitoring and alarm network system, and the important role of data transmission scheme is becoming increasingly prominent. EPON, which can provide high bandwidth access, has become an important technology that its large-scale commercial use relies on.
With the development of communication technology, EPON technology has been gradually introduced into the field of security monitoring. It is a bandwidth access technology of point-to-multipoint network structure and passive optical fiber transmission mode.
At present, the advantages of EPON technology are gradually reflected, especially in Cameras and Surveillance application. When EPON is applied to the monitoring network mode, it can give full play to its advantages of high bandwidth while solving the basic video data transmission at low cost, and its simple and flexible characteristics can greatly reduce the overall cost and maintenance cost of the network.
EPON network has the following advantages:
1.High reliability. EPON is a splitter and optical fiber. It has a long service life and no active equipment. It avoids power failure, lightning strike, overcurrent and overvoltage damage, etc. The network has high reliability and reduces maintenance costs.
2.low cost. EPON technology for single-core fiber transmission, saving half of the fiber than ordinary fiber transmission. In addition, EPON does not require an external power supply during transmission, is easy to lay, and basically requires no maintenance, which can save operating costs and management costs.
3.High bandwidth.1Gmps symmetric transmission rate, can easily meet the bearing requirements of video surveillance services. The bandwidth of each ONU can be dynamically adjusted between 2M and 1Gmps. The average upstream bandwidth of an OLT port in each ONU is about 30M, which fully meets the IPTV requirements.
4.EPON has high cost performance and the EPON speed can reach the same high bandwidth of the upstream and downstream of 1.25Gb/s.The maximum speed can reach 10Gb/s, maximum transmission distance can reach 20km, which is very suitable for the coverage of metropolitan area network, and basically covers the range of medium-sized area.
5.The networking is flexible, and the highest optical split ratio is 1:64. The tree-shaped network structure is adopted to form a point-to-multipoint user network topology through the combination of different optical splitters. Through reasonable network planning and design, fiber resources can be saved to the utmost. It is a good solution to the problem of image collection and dispersion.
EPON Technology Principle
EPON（Ethernet Passive Optical Network）The Ethernet passive optical network is the product of the perfect combination of Ethernet technology and PON technology.
In order to separate signals in the transmission and reception direction of multiple users on the same fiber, the following two multiplexing technologies are adopted: the downlink data stream adopts broadcast technology, and the uplink data stream adopts TDMA technology.
EPON application in Cameras and surveillance
EPON technology is characterized by high bandwidth, high stability and high utilization of line resources. This technology has its natural advantages for campus monitoring.First, campus monitoring requires a high-speed, high-quality private network environment to carry its high-quality video services.EPON technology provides uplink and downlink symmetric 1Gbps bandwidth, which can fully meet the needs of video services.Secondly, EPON’s flexible topological structure maximally takes care of the scattered layout of the park.Whether it is a dense group of buildings or a sparse road, it can be fitted with appropriate network.Finally, the high security and stability of EPON also elevate the access technology level of park monitoring to a new level.
When high-density monitoring points are needed in the center of the park, EPON can adopt typical networking. One PON port of OLT equipment is connected with 1: N spectrometer. After reaching the front-end optical node, multiple ONU devices are connected.Take full advantage of the length of optical fiber transmission, extending to every need to be deployed in the area.The spare fiber can be reserved for later expansion access.
The monitoring of the surrounding roads can be done in a zigzzagging way to connect the road monitoring points in series.In a small regional environment, EPON with an effective length of 20KM can provide access. In a large area, multiple routes can be used to solve the distance problem.