Telecom Cables, Fiber Optics, and Satellite Communication

Coaxial Cable Specifications

A coaxial cable features a copper connector at its center, covered by an insulating layer, then a layer of armor, and finally an outer coating layer. It uses BNC connectors (type and tipoF). Coaxial cables are not very flexible, support speeds of 10 Mbps, and require a connection to ground.

Uses and Applications of Copper Wires

• Coaxial Cable: Used in radio frequencies modulated as cable TV.
• Twisted Pair: Used for data transmissions and VoIP.

Fiber Optic Cable Elements

• Core: The element that transmits light, located at the center of the fiber optic cable (FOR). The core is made of silica or glass.
• Cladding: Covers the core.
• Buffer: Helps protect the core and cladding from damage.
• Resistant Material: Prevents the buffer surrounding the fiber optic cable from stretching when pulled.
• Outer Coating: Protects the fiber from abrasion, solvents, and other pollutants.

Types of Fiber Optic Cables: Single-Mode vs. Multi-Mode

• Single-Mode: Small core, less divergence, suitable for long-distance applications, often uses a laser light source.
• Multi-Mode: Larger core than single-mode, more divergence, reaches a shorter distance than single-mode, usually uses an LED light source.

Advantages and Disadvantages of Fiber Optic Cables

• Advantages: Electromagnetic immunity, non-conductivity, greater safety, lower attenuation, higher bandwidth, small diameter and weight, long-term economy.
• Disadvantages: Higher initial cost than copper, less resistant to abuse than copper cable, more delicate connectors, fiber connection requires a higher level of skills and knowledge, more expensive tools and gauges.

Types of Satellites

• Geostationary Satellites (GEO)
• Low-Orbit Satellites (LEO)

Transponder Concept

A transponder is a receiver/transmitter on a communications satellite. It receives a signal transmitted from the earth (uplink), amplifies it, and retransmits it back to earth at a different frequency (downlink).

Types of Errors in Telecommunications

• Bit Errors: Only change one bit of a data unit.
• Multiple Errors: Several errors in various positions of the data unit.
• Burst Errors: Changing multiple bits, consecutive or not.

Concept of Redundancy

Redundancy is the extra information sent for the detection/correction of errors and is not necessary if we can ensure the absence of faults.

Types of Redundancy Checks

• VRC: Vertical Redundancy Check
• LRC: Longitudinal Redundancy Check
• CRC: Cyclic Redundancy Check
• Checksum: Checksum