Understand Passive and Active Network Technology
Understand Passive and Active Network Technology
by Fiber-MART.COM
Nowadays, we have access to more information than ever before. We live in a digital world and bandwidth is what makes a digital world happen. There are many types of networks carrying different types of information. However, all these individual networks can be divided into two categories: passive and active. A passive network does not use electrically powered equipment or components to get the signal from one place to another, while an active network uses electrically powered equipment or components to route the signal from one place to another. This article will briefly introduce both passive and active fiber/copper networks.
Passive Copper Network
There are many different types of passive copper networks, but the one virtually everyone is familiar with is their home cable TV network. In a copper cable TV network, the cable provider supplies the signal to the home over a coaxial cable. The cable enters the home and is routed to a single television. However, few homes have a single television. For homes with multiple TVs, the signal from the cable provider must be split for each television to receive the signal. The splitting is usually accomplished with a splitter. The splitter requires no electrical power. It will typically have a single input and may have two, three, four, or more outputs. The following picture is an example of a splitter that has a single input and four outputs. An individual cable is routed from the splitter to each television.
With this type of network, loss of signal strength will occur. As the signal from the cable provider is split and routed to multiple televisions, the signal strength to each television is reduced. Adding too many televisions can reduce the signal strength to the point where none of the televisions receives adequate signal strength to operate properly. When this happens, it is time to install an active cable TV network.
Active Copper Network
Same with the passive copper networks, there are also many types of active copper networks. The previous section focused on a passive home cable TV network and pointed out that you can only connect a limited number of televisions to this type of network. In order to have adequate signal strength for multiple televisions, for example, one in each room, an active network is required. In an active home cable TV network, one cable enters the home and is routed to a distribution amplifier. The distribution amplifier boosts or amplifies and splits the signal from the cable provider. Each output of the distribution amplifier has a signal strength approximately equal to the signal strength on the input cable from the cable provider. An individual cable is routed from the distribution amplifier to each television.
This type of active network overcomes the signal strength problem associated with a passive network. However, it does add a level of complexity and requires power. If the distribution amplifier were to fail, all the televisions would lose their signals. The same would be true if the distribution amplifier were accidentally unplugged: every television in the house would be without a signal.
Various types of passive optical networks (PON) are available, and one of the most common types is very similar to the passive cable TV network previously described. However, optical fiber is used instead of coaxial cable. In any PON, couplers are the core. A coupler may combine two or more optical signals into a single output, or the coupler may take a single optical input and distribute it to two or more separate outputs. The following picture is an example of a seven-port coupler. The coupler is splitting a single input signal into six outputs.
coupler
Many couplers are designed for bidirectional operation, which enables the same coupler to be used either to combine signals or to split signals. In a bidirectional coupler, each port can be either an input or an output. However, for a PON application, a coupler being used to split a signal may be referred to as a splitter. In a PON, the input to the coupler in the picture above would be split equally between the six outputs. Data going into the coupler would be sent to each output just as the signal from the cable TV provider is sent to each TV in the passive copper network. Although each output will carry the same information as the input, the signal strength will be reduced based on the number of outputs. There is a finite limit on the number of outputs for a PON application; typically, the limit is 32. However, some applications may support more.
Active Optical Network
An active optical network is very similar to the active home cable TV network previously described. One optical fiber connects to a switch instead of a distribution amplifier. The switch rebroadcasts the data to each individual user. A separate cable is routed from the switch to each individual user. This type of active network overcomes the signal strength problem associated with a passive network. However, it does add a level of complexity and requires power. If the switch were to fail, all the users would lose access to incoming data. The same would be true if the switch lost power: data would stop flowing.
Conclusion
Some basic information about passive copper network, active copper network, passive optical network and active optical network has been described in this article. And each kind of network has their own features. Before choosing a certain one, please make clear all the related information and then install it.
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