Hello again dear friends! Before that, we mostly discussed with you issues related to communications systems to transmit signals using electrical impulses, and now it is time to talk about another type of communication systems based on the use of optical pulses - fiber optic communication systems.
Existing communication systems that move data over copper, nice to everyone, except the distance to which they can transmit information (without intermediate amplification of points) is pretty limited. This eliminates the drawback of fiber-optic transmission systems.
As probably not hard to guess all the usual copper communication cables are not suitable for optical signal transmission. Therefore, the fiber-optic networks used by another type of cable - optical cables. Outside (outer shell), these cables are similar to conventional copper cables (although there are some differences), but inside they contain are not familiar copper wires and optical fibers specially designed for the transmission of optical pulses. Typically, optical fibers made of quartz glass or certain types of plastic and have the following structure:
 |
| Design of optical fiber |
As seen from the figure, the optical fiber is composed of two parts: the core and the shell. The core and the shell made of the characteristics of different materials, with consideration to the refractive index of the core was slightly higher than the refractive index of the shell. With such a ratio of the refractive indices, the light beam entering the core of the optical fiber, will be distributed by him due to the effect of total internal reflection occurs at the boundary between two media (the core and the cladding of an optical fiber).
By themselves, the optical fibers are relatively fragile, so they are covered by a special membrane buffer, and then combined in the optical modules, which are covered from above with additional protective layers. In general, the design of optical cable can be as follows (but in fact it may be different):
For the introduction of an optical signal into an optical cable (and thus taking it to the other side of the cable) are special optical transceivers, which in practice is usually built into SFP modules are designed for installation in a variety of network devices, or directly in the optical device ports.
 |
| Skin and SFP modules |
Consider how the direct connection of multiple network devices using fiber optics. Suppose we have two switches with connectors for SFP modules (if there is no switch with a socket for the SFP modules, you can use the circuit switch - media converter).
 |
| Switch with SFP connectors to install modules |
In the SFP ports on the switch are installed SFP modules. Specific model SFP modules selected based on design requirements (required transmission distance, the type of optical cable, etc.).
 |
| Installing SFP Modules |
For connectors installed SFP modules are connected optical patch cords (actually too optic cable, but containing only 1 or 2 fibers, and having a simple structure), the other end of the optical patch cords are connected to the terminals of optical distribution frame. Optical patch cords may have different optical connectors at its ends, the choice of a particular model (with certain connectors) is determined by optical connectors SFP modules and connectors optical distribution frame.
 |
| The appearance of the optical patch cord |
Optical Distribution Frame roughly represents a metal box with connectors, which are connected outside optic patch cords and pigtails in (generally half the optical patch cord, used for okontsovyvaniya trunk optical cable). Also located inside the optical cross special cassettes and apparatus for fixing cables.
On the other side of the optical cross comes backbone fiber optic cable that will connect two remote sites.
 |
| The principle of operation of optical distribution frame |
If you collect the whole scheme together, it will look like the following:
 |
| Connecting two remote sites using fiber-optic network |
That's pretty hard not possible to connect two remote sites using the means of fiber-optic communications.
No comments:
Post a Comment