Based on passive optical network technology for video surveillance systems (1)

As modern cities towards the development of multiple functions, increasingly complex urban layout, ground control points have hundreds and hundreds or even thousands, to ensure the functions of the departments in the first time a clear grasp of real-time, high-quality video images, bestowed tension fiber resources.

Also, the city is becoming more powerful and complex functions, relaying cable not only cost an arm and a leg, each party's coordination more difficult. In view of this, how to solve these problems?

In fact, in the telecom operator's FTTH (fiber to the home) construction faced the same problem.

To resolve this problem, give full play to the advantages of fiber-optic bandwidth, resolving fibre resources tension, improves the robustness of the network, telecom carriers chose PON (passive optical network) technology.

However, the operator's PON networks, usually transport Ethernet signal, and if you want to host video surveillance, it can only transmit low-bandwidth compression video signal, there is no guarantee that the video quality.

In order to save the fibre and transmission of high-quality non-compressed video, VPON (Video over PON) a concepts came into being, as a "safe city" monitoring point video access provides a new solution.

The advantages of PON

PON (Passive Optical Network) that is passive optical network.

A passive optical network includes an installation in the central control station of the optical line terminal (OLT), as well as a complete set of installation on the user's premises and optical network unit (ONU). The OLT and ONU between optical distribution network (ODN) contains fiber and passive optical device or coupler.

Passive optical network from Center to the resident network between does not have any active devices, instead the passive optical device plugged into the network, and the entire path through separate optical wavelength of power to guide the flow of transfer.

This substitution allows users no longer need to transport loop of active devices for energy and maintenance savings on the cost of the user. Passive optical device and coupler only to pass and limit the role of light, do not need electricity and information processing, and with unrestricted mean time between failures (MTBF), can reduce maintenance costs.

PON technology advantages mainly reflected in the following areas:

· Optical access network is the best way to accommodate future development of the solution, in particular the PON technology has proven to be the current comprehensive broadband access in a very cost-effective manner.

· Due to the entire light PON technology distribution network is passive, passive optical networks of small and simple.

Compared with copper cable networks, PON can reduce maintenance costs, and run completely avoids interference EMI and lightning.

Passive · PON ONU (optical network unit) without power supply, not only from the power supply of a series of questions, and reliability than active devices.

· Due to the use of passive components, shared fibre transmission media, an entire optical network investment costs low.

· PON to some extent on the use of the transmission system is transparent, it is easier to upgrade.

PON technology has become an industry recognized for fiber to the home (FTTH) preferred programme.

PON technology with point-to-multipoint topology, downlink and uplink respectively by TDM and TDMA manner transmit data. Currently, the telecommunications industry is the major publicity EPON, namely Ethernet encapsulation to achieve fibre broadband PON, households.

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