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Fibre Optics Based on Multi Point Fibre Optic Distribution System

Multi point fibre optic distribution system is the broad wireless technology used to deliver voice, data, Internet, and video services. It has been allocated for that deliever broadband services in a point to point or point to multi point configuration to residential and commercial customers. As a result of the propagating characteristics of signals so that the systems use a cellular like network architecture, though services provided are fixed, not mobile.

In some cases fibre optic distribution system has an ability to connect several remote sites to one base station. One common application is that the repeaters based on a major building and others building such as RF shielding areas and basement which all located in a few miles repeater building. A and the repeater use the head end. A multiple fibre optic transceiver assembly at the base station is commonly called a “head end” The distance end of the fibre is called “remote hub” equipment.

fiber optic distribution system

We need to pay attention to that each fibre optic receiver output at the repeater site has individual pads to reduce the composite noise floor. For example, if used the 40dB, an additional 80 dB of combiner port-to-port isolation occurs. In real application, it is a good idea, including regard the taps at test point to read the RF levels. Just used for testing and protection. A similar system that when we used the WDM, if the numbers of fibres are reduced by 50% but a WDM must be added at each remote site and another WDM for each fibre added at the repeater site. In the 4 remote site example, it would be taking 8 WDM’s to operate all the fibres full duplex and 4 fibre optic transmitters would have to be 1550nm models. Then there also a point we need to be careful. Fibre optic transceiver is not frequency selective and the same unit can receive 1330 or 1550nm optical signals equally well. We also measured the noise performance and we are happy to inform you that in line with theory, optic splitters practically do not add any noise. No matter what output we tested, this means that your receiver connected to such network would also show very high quality readings.

When we use the fibre optic links in the fibre optic distribution system, sometimes we need fibre optical splitter to split the signal which carried. The system designer has the choice of splitting either the optical or RF domain. The function of optical splitter is familiar to RF splitter. Other parts of the incoming fibre optic network are connected to the transmission of output, and the terminal device is connected and the another main part is its direct part. There are also splitters that divided the input into 2, 4 or more outputs. According to the structure and locations of fibre optic splitter, in the fibre optic network, we need different split ratios of splitter, such as 1×2, 1×4 and 1×8 splitter?and so on. Moreover unused single mode fibre cable, specific products can see at 50m single mode, it also can strengthen the signal used for the RF over fibre optic systems between the connected buildings for data communication and spare fibres.

Article Source: http://www.fiber-optical-networking.com/2015/02/09/fiber-optics-based-on-multi-point-fiber-distribution-systems/

About Multimode Fibre

Multimode fibre is a kind of optical fibre mostly used in communication over short distances, for example, inside a building or for the campus. Typical multimode links have data rates of 10 Mbit/s to 10 Gbit/s over link lengths of up to 600 meters (2000 feet) – greater than sufficient for almost all premises applications.

Multimode fibre optic cable has a large diametral core which allows multiple modes of light to propagate. For this reason, large number of light reflections created because the light goes through the core increases, creating the ability for more data passing at a given time. Due to the high dispersion and attenuation rate using this type of fibre, the number of the signal is reduced over long distances. This application is commonly used in short distance, data and audio/video applications in LANs. Broadband RF signals, such as what fibre optic companies commonly use, can’t be transmitted over multimode fibre.

Multimode fibre is generally 50/125 and 62.5/125 in construction. It means that the core to cladding diameter ratio is 50 microns to 125 microns and 62.5 microns to 125 microns.

50-125

Multimode fibres are recognized by the OM (“optical mode”) designation as outlined in the ISO/IEC 11801 standard.

  • OM1 Fibre, for fibre with 200/500 MHz*km overfilled launch (OFL) bandwidth at 850/1300nm (typically 62.5/125um fibre)
  • OM2 Fibre, for fibrewith 500/500 MHz*km OFL bandwidth at 850/1300nm (typically 50/125um fibre)
  • OM3 Fibre, for laser-optimized 50um fibre having 2000 MHz*km effective modal bandwidth (EMB, often known as laser bandwidth), created for 10 Gb/s transmission.
  • OM4 Fibre, for laser-optimized 50um fibre having 4700 MHz*km EMB bandwidth made for 10 Gb/s, 40 Gb/s, and 100 Gb/s transmission.

Multimode Fibre Types

The transition between the core and cladding can be sharp, which is named a Step-index multimode Fibre, or a gradual transition, which is named a Graded-Index multimode Fibre.

Step-Index Multimode Fibre – Because of its large core, a few of the light rays that constitute the digital pulse may travel a direct route, whereas others zigzag as they bounce off the cladding. These alternate paths result in the different groups of light rays, identified as modes, to reach separately at the receiving point. The pulse, an aggregate of different modes, starts to disseminate, losing its well-defined shape. The necessity to leave spacing between pulses to avoid overlapping limits the quantity of information which can be sent. This kind of fibre is most effective for transmission over short distances.

Graded-Index Multimode Fibre – Includes a core in that the refractive index diminishes gradually from the centre axis out toward the cladding. The higher refractive index in the centre makes the light rays moving down the axis advance more slowly than these near the cladding. Because of the graded index, light in the core curves helically rather than zigzag off the cladding, reducing its travel distance. The shortened path and the greater speed allow light at the periphery to reach a receiver at about the same time as the slow but straight rays in the core axis. The end result: digital pulse suffers less dispersion. This kind of fibre optic cable is most effective for local-area networks.

Applications

The device used for communications over multi-mode optical fibre is cheaper than that for single-mode optical fibre.Typical transmission speed and distance limits are 100 Mbit/s for distances up to 2km (100BASE-FX), 1 Gbit/s up to 1000m, and 10 Gbit/s up to 550m.

Due to its high capacity and reliability, multi-mode optical fibre usually used for backbone applications in buildings. A large number of users consider the advantages of fibre nearer to the user by running fibre to the desktop or to the zone. Standards-compliant architectures such as centralized cabling and fibre to the telecom enclosure offer users the opportunity to leverage the distance capabilities of fibre by centralizing electronics in telecommunications rooms, instead of having active electronics on each floor.

How FTTH Broadband Works?

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Stop and think how your Internet usage has evolved during the last few years. If you’re like most people, you will do, and looking forward to more online interaction, such as increasing rich media and upload and download images and video.

More large files are moving across the cyberspace network these days, and experts expect that trend will only increase. In January 2008, the study by the Discovery Institute estimates new technologies will drive Internet traffic up by 50 times its current rate within the next 10 years.

The pressure for better connectivity is one of the main reasons providers and users to view its fibre to the home broadband connections as a potential solution.

FTTH broadband connections, refer to optical fibre cable connection for individual residences. Such optical based system can provide large amounts of digital information, telephone, video, data, and so on, more efficiently than traditional copper coaxial cable for about the same price. FTTH premises depend on both active and passive optical networks to function.

FTTH network cables connection is a reality of more than 1 million consumers in the United States, and more than 6 million Japanese and 10 million global to enjoy its benefits, broadband property according to the magazine. Many people think that the FTTH technology standard to predict network connection can solve traffic congestion.

More than 10 million homes worldwide already have fibre to the home broadband connections because the technology holds many advantages over current technologies.

What are the advantages to FTTH broadband connections?

A key advantage to FTTH – also called FTTP, for “fibre to the premises” broadband – is that it provides for far faster connection speeds and carrying capacity than twisted pair conductors, DSL or coaxial cable. Experts at the FTTH Council say fibre-to-the-home connections are the only technology with enough bandwidth to handle projected consumer demands during the next decade reliably and cost effectively. The technology is already, affordable, as businesses around the world are demonstrating by getting into the business as they speculate on consumer demand.

Fibre has a virtually unlimited bandwidth coupled with a long reach, making it “future safe,” or a standard medium that will be in place for a long time to come.

However, greatly improving the bandwidth cost and current technology. According to the FTTH Council, cable companies spent about $84 billion to line family ten years ago, but it costs less in today’s dollars line those houses with FTTH technology.

FTTH will be able to handle even the future Internet use some experts see the future. Technologies such as 3D holographic high definition television and games will one day become daily necessities of families all over the world. FTTH will be able to handle estimated 30-gigabyte-per-second needs of such equipment.

Active and Passive Optical Networks

There are two important types of systems that make FTTH broadband connections possible. These are active optical networks and passive optical networks. Each offers ways to separate data and route it to the proper place, and each has advantages and disadvantages as compared to the other.

An active optical system uses electrically powered switching equipment, such as a router or a switch aggregator, to manage signal distribution and direct signals to specific customers. This switch opens and closes in various ways to direct the incoming and outgoing signals to the proper place. In such a system, a customer may have a dedicated fibre running to his or her house.

A passive optical network, on the other hand, does not include electrically powered switching equipment and instead uses optical splitters to separate and collect optical signals as they move through the network. A passive optical network shares fibre optic strands for portions of the network. Powered equipment is required only at the source and receiving ends of the signal.

Active and Passive Optical Networks of the advantages and disadvantages

Passive optical networks, or PONs, have some distinct advantages. They’re efficient, in that each fibre optic strand can serve up to 32 users. PONs have a low building cost relative to active optical networks along with lower maintenance costs. Because there are few moving or electrical parts, there’s simply less that can go wrong in a PON.

Passive optical networks also have some disadvantages. They have less range than an active optical network, meaning subscribers must be geographically closer to the central source of the data. PONs also make it difficult to isolate a failure when they occur. Also, because the bandwidth in a PON is not dedicated to individual subscribers, data transmission speed may slow down during peak usage times in an effect known as latency. Latency quickly degrades services such as audio and video, which need a smooth rate to maintain quality.
Active optical networks offer certain advantages, as well. Their reliance on Ethernet technology makes interoperability among vendors easy. Subscribers can select hardware that delivers an appropriate data transmission rate and scale up as their needs increase without having to restructure the network.

Active optical networks, however, also have their disadvantages. They require at least one switch aggregator for every 48 subscribers. Because it requires power, an active optical network inherently is less reliable than a passive optical network.