Hello, let's go to the next concepts that need to be established:
1 - How is the transmission of signals done?
2 - What are the available means of transmission?
3 - What is structured cabling?
1 - There are two types of signals that are analog and digital.
The analog signal is a signal that takes different values and variations and varies as a function of time. For example, there is the measurement of speed and temperature, all possible values are measured.
The digital signal depends on a coding for discontinuous values, unlike the analog signal that takes different values, the digital signal takes defined values in the form of steps or jumps.
The ways to represent the signs are:
Waves: with wavelength and frequency, with these two parameters it is possible to determine the propagation speed of the signal through a medium. You need to have a basic knowledge of physics here. The types of where are:
Sinusoidals: for analog signals
Squares: for digital signals
There are also the triangular and sawtooth waves.
Some forms of signal degradation are:
Mitigation
Noise
Reflection or Echo
The digitization process is divided into 3 steps, which are:
Sampling
Quantization
Codification
The encoding types are: NRZI (non return to zero inverted), Manchester and Differential Manchester. Of these, the most important for our study is MANCHESTER, the ethernet uses this type of encoding.
About the characteristics of the signals transmitted in a medium is that of baseband and passband.
Base Band: Reflects the original frequency (band) width.
Passing Band or Broadband: It is the modulated signal to travel in a certain frequency range.
With these concepts we can define as BANDWIDTH the difference between the highest and lowest frequency that can be used in a medium or channel.
There is also the concept of Multiplexing, which consists of transmitting several signals in a single medium through the creation of internal channels.
2 - As means of transmission we have coaxial cable, twisted pair cable, fiber optic cable and air in wireless networks, here's a basic explanation about each of them:
Coaxial cable:
It is a cable used by cable TV operators that together provide internet access. It is a metallic cable, therefore a guided medium, with a sheathing mesh for insulation against interference. It is falling into disuse, transmits at greater distances than the twisted pair, but it is more expensive and less malleable. Types are: 10BASE2 and 10BASE5.
Twisted pair cable:
Medium guided, wide use on LANs with a maximum distance of 100m in all standards. Braiding is used to reduce interference. Below is a table with the cable standards:
This table I found on the internet but it may have some incorrect values, as I have seen divergence between these tables on the internet.
UTP cable does not have any type of shielding but there are other types such as FTP, which has an external shield covering all the twisted wires, there is STP which has a coating on each of the twisted pairs and there is also SSTP, which has shielding in each of the cables and also a shield involving all pairs, double shielding.
Fiber Optic Cable:
It uses light refraction to transmit signals, is a guided medium, has immunity to electromagnetic interference, reaches long distances, and has high transmission rates. To generate the light signal you can use LEDS or LASERS. There are basically two type a multimode which has several light signals being transmitted, has a shorter range and singlemode which has only a central light beam and reaches greater distances than multimode.
Here are some fiber patterns:
As stated before the values in these tables may vary. The attenuation in the fibers is due to absorption, scattering, mechanical deformations and dispersion factors.
Wireless Networks
Everyone knows the benefits of wireless networks, it uses electromagnetic signals for transmission, giving it more mobility, avoiding use and disorganization with many cables. You should think about using a wireless access point so that it is not subject to interference, then you should think about the frequency to be used, the channel, security and location. Below is a table with the main patterns:
3 - About structured cabling it can be said that it is a series of standards and norms for the best use and configurations of cabling in a building, a house, a campus and others. Here are some concepts:
- Horizontal Cabling: It is characterized by the cabling that interconnects the telecommunications room to the work areas. It has this name, as it usually distributes the cabling within the same floor of the building. A characteristic of this type of cabling is that the recommendation is that it be up to 90 meters, leaving 10 meters for maneuver in the telecommunications room.
- Backbone cabling: it is characterized by connecting the telecommunications rooms to the equipment rooms. It also includes the connection between the entrance of the building and the Equipment room.
- Equipment Room: Area destined to the storage of the main active equipment of the network, such as servers, core switches, routers and PABX.
- Telecommunications Room: Area for the accommodation of equipment and
distribution terminators. It is also used as a maneuvering area for structured cabling. It also features the fact that it interconnects the backbone cabling to the horizontal cabling through the room equipment.
- Work Area: Physical area for workstations, that is, an area effectively used by users to work with communication equipment (computers, telephones, printers, etc.).
- Building entrance: it is the connection point between the external and the internal cabling (intra building). Arrival point of operators and other services in the building. It's usually inside the Equipment room.
- External Interconnection: It is responsible for making the interconnection between different buildings, connecting the Entrance of Building A to the Equipment Room of building B.
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