Wireless Communication and Fiber Optics: Types and Advantages
Wireless Communication: Types and Characteristics
Light Waves (Laser)
Light waves, specifically lasers, enable communication between different areas with a direct line of sight. They transmit in a straight line and do not pass through objects. Lasers are one of the most commonly used forms of light wave communication.
Infrared Waves
Infrared waves are widely used for short-range communication, such as in remote controls for televisions and VCRs. A significant drawback is that they do not penetrate solid objects.
Microwaves
Microwaves allow both terrestrial and satellite transmissions, with possible speeds of around 10 Mbps. Unlike radio waves, microwaves do not penetrate obstacles well, necessitating relay masts for long-distance communications.
Radio Waves
Radio waves are easy to generate, can travel long distances, penetrate buildings, and travel in all directions from their source. Because these networks cover long distances, governments strictly control them to prevent interference between different transmissions.
Wireless or Unguided Media
Wireless communication involves sending and receiving electrons through space, such as air. These particles travel as electromagnetic waves, propagating similarly to ripples in a pond.
Fiber Optics: Advantages and Connection Methods
Advantages of Using Fiber Optics
- Bandwidths are much larger than copper.
- Due to its low attenuation, repeaters are only needed every 30 km, compared to 5 km for copper.
- It’s thin and light, especially compared to copper wires of equal speed.
- Fiber does not leak and is very difficult to intercept.
Ways to Join Two Fiber Optic Cables
- Using Connectors: Each section of fiber can come with factory-installed plugs on each end. This method is simple but results in a 10-20% loss of light at the connection.
- Mechanical Joints: Each end is carefully cut and attached by a special sleeve. Alignment can be improved by passing light through the junction and making small adjustments. These joints have a 10% light loss.
- Fusing the Two Ends: The two sections are fused to form a solid connection. This joint is almost as good as a single fiber, but some attenuation still occurs.
Fiber Optic Cable: Light Transmission Methods
Single-mode
The fiber is so thin that light is transmitted straight through. The core has a radius of 10 microns, and the cover is 125 microns. It has less dispersion and is suitable for long-distance applications, using a laser as a light source. It is commonly used for distances up to 3 km.
Multimode
Light is transmitted through the core, reflecting off its inner surface like a mirror. Light losses are practically nil. The core has a diameter of 100 microns, and the cover is 140 microns.
Graded-Index Multimode
Light propagates through the core by gradual refraction. The core’s refractive index increases from the center towards the ends. It usually has the same diameter as multimode fiber.
Fiber Optics: Components of an Optical Transmission System
Fiber optics rely on light pulses to transmit binary information. An optical transmission system has three components:
- Light Source: Converts a digital electrical signal (0 or 1) into an optical signal. A light pulse represents a 1, and the absence of light represents a 0.
- Transmission Medium: An ultrathin glass fiber that carries the light.
- Detector: Generates an electrical pulse when light falls on it.
Coaxial Cable: Types and Applications
Types of Coaxial Cable
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Baseband Coaxial: Used in digital transmission. The maximum bandwidth depends on cable length. A 1 km cable can achieve speeds up to 10 Mbps, and shorter cables can achieve higher speeds. There are two types:
- Thick Coaxial: Initially used in local networks, now used for backbone network distribution. Examples include RG-100 and RG-150.
- Thin Coaxial: More flexible and easier to install but more expensive and less immune to interference. The most common type is RG-58.
- Broadband Coaxial: Used for analog transmission, commonly for cable TV signals.
Coaxial Cable Structure
Coaxial cable is a widely used transmission medium. It has better shielding than twisted pair, allowing for higher transmission speeds and longer segments between repeaters. It consists of a hard copper wire at its center, carrying the signal, surrounded by insulating material.