Informática para Concursos - Aula 01.6 - Redes - Meios de Transmissão - Não-guiados e Guiados

Summary

In this video, the professor explains various network transmission mediums, such as wired and wireless options. The discussion includes the differences between guided (e.g., coaxial cables, twisted pair, fiber optics) and unguided transmission (e.g., radio waves, Bluetooth, Wi-Fi). The professor dives into details about how data is transmitted through these mediums, emphasizing the benefits and limitations of each. Topics such as electromagnetic interference, bandwidth, and the cost of fiber optics are also covered. The session is designed to help viewers understand these concepts clearly, especially for exam preparation in networking.

Takeaways

• 😀 Transmission mediums in networks are either guided (via cables) or unguided (wireless).
• 😀 Guided transmission involves cables like coaxial cables, twisted pair cables, and fiber optics, each with unique features and applications.
• 😀 Unguided transmission refers to wireless technologies such as radio waves, Bluetooth, and Wi-Fi, which are all considered wireless (not strictly Wi-Fi).
• 😀 Coaxial cables, once widely used in computer networks, are still used for TV antennas but are less common today due to technological advancements.
• 😀 Twisted pair cables, particularly the unshielded variety (UTP), are the most commonly used type of cable in modern networks due to their affordability and flexibility.
• 😀 Shielded twisted pair (STP) cables offer additional electromagnetic interference protection compared to UTP cables, but are more expensive.
• 😀 Fiber optics is the most advanced transmission medium, offering virtually infinite transmission capacity and immunity to electromagnetic interference.
• 😀 Fiber optic cables consist of a core of glass or plastic that transmits light signals, making them faster and more reliable over long distances than copper cables.
• 😀 There are two types of fiber optic cables: multimode (for short distances with light reflecting off the inner walls) and single-mode (for long-distance transmission with light traveling along a single path).
• 😀 Fiber optics are used extensively by internet providers for long-distance communication due to their high data capacity and minimal signal degradation.
• 😀 Despite the advantages, fiber optics are costly and have limitations in bending or curving sharply, making them less suitable for certain applications.

Q & A

What are the two main types of transmission media in computer networks?

The two main types of transmission media are guided transmission (wired) and unguided transmission (wireless). Guided transmission uses cables like coaxial, twisted pair, and fiber optic, while unguided transmission relies on electromagnetic waves such as radio waves, Bluetooth, and Wi-Fi.

What is the primary difference between guided and unguided transmission media?

Guided transmission uses physical cables to carry signals, whereas unguided transmission relies on electromagnetic waves that travel through the air without the need for physical cables.

What is the function of shielding in coaxial cables?

Shielding in coaxial cables is used to protect the signal from electromagnetic interference (EMI) and ensure that the signal can travel without degradation from external sources of noise.

Why is fiber optic cable considered immune to electromagnetic interference?

Fiber optic cable transmits data using light signals instead of electrical signals, making it immune to electromagnetic interference, as light does not interact with electromagnetic fields in the same way electrical signals do.

What are the advantages of twisted pair cables in networking?

Twisted pair cables are inexpensive, flexible, and relatively easy to install. They are widely used in local area networks (LANs) due to their affordability and ability to transmit data at reasonable speeds over short to medium distances.

What is the difference between UTP and STP cables?

UTP (Unshielded Twisted Pair) cables do not have any additional shielding, making them less resistant to interference. STP (Shielded Twisted Pair) cables, on the other hand, have a metallic shield to further protect the signal from electromagnetic interference.

How do multimode and singlemode fiber optic cables differ?

Multimode fiber optic cables allow light to reflect within the fiber core, supporting multiple paths for light. They are typically used for shorter distances. Singlemode fiber optic cables allow light to travel in a straight line through the core, making them ideal for long-distance transmission.

Why are fiber optic cables more expensive than twisted pair cables?

Fiber optic cables are more expensive due to the higher cost of materials, specialized equipment required for installation, and their capability to support faster data transmission over longer distances. They are also less flexible and harder to manage than twisted pair cables.

What is the maximum range of transmission for twisted pair cables?

The maximum transmission range for twisted pair cables is typically up to 100 meters for Ethernet connections. Beyond this distance, signal degradation can occur, which is why repeaters or switches are used in larger networks.

What is the main advantage of using fiber optics in large-scale networks?

The main advantage of using fiber optics in large-scale networks is its ability to transmit data at extremely high speeds over long distances with minimal signal loss and no interference from electromagnetic fields, making it ideal for backbone connections in large data centers and between cities.