Internet users can enjoy internet services if connected using WiMAX. Explain how it works.21/11/2022 Internet users can enjoy internet services if connected using WiMAX. Explain how it works.Worldwide Interoperability for Microwave Access (WiMAX) is an internet protocol (IP) based on terrestrial microwave broadband internet connection over a metropolitan area for distances of upto 15 kilometres. It provides conditions similar to Wi-Fi but at longer distances and good quality of service (QoS).
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Using an illustration, explain how data is transmitted on terrestrial microwave relay stations.21/11/2022 Using an illustration, explain how data is transmitted on terrestrial microwave relay stations.Microwaves have frequencies ranging from 30 - 40 GHz on the electromagnetic spectrum and wavelengths of upto a few metres.
They have the ability to penetrate haze, snow and even clouds. They are transmitted in a unidirectional manner; making them suitable for point to point links using concave antennae. The transmitting dish sends a unidirectional microwave beam towards the receiving dish. Due to their high bandwidth, terrestrial microwave stations can be used to transmit heavy multimedia data between the source and the destination. Laptops and high end phones have been observed to access the internet wirelessly in some modern restaurants, airport lounges and designated public areas. Identify the type of connectivity and features that enable this to happen.Wireless fidelity (Wi-Fi) or wireless LAN hotspots allow notebook PCs and other hand held devices such as WLAN-enabled mobile phone to access the internet. The hotspot is set up by a Wi-Fi router which enables the roaming device to remotely connect to the organisation's internet services.
Bluetooth connectivity has its benefits and limitations. Explain.The main advantage of bluetooth is that it is a high speed short range wireless communication medium. Its main disadvantage is that bluetooth enabled devices are at a risk of illegal surveillance and their data being illegally accessed due to their wireless discoverability.
A mobile phone user observed that every time her phone came close to her neighbours phone (within 300 m radius), a prompt appeared on the screen asking whether a connection should be established. Explain the most probable wireless connectivity available on both mobile phones.Bluetooth It provides short range communication of upto 300 metres radius between devices. Bluetooth-enabled devices within that range can automatically detect each other hence communicating.
Differentiate between bluetooth and infrared transmission media.Bluetooth is a short range radio wireless communication medium that can pass through barriers like a wall hence not limited to line- of-sight transmission. Infrared transmission, on the other hand, as uses infrared rays to transmit data along the line-of-sight hence it cannot penetrate walls.
A passenger on a cruise ship observed that while on high seas, the crew sent messages to land by transmitting the radio waves towards the sky. Describe this type of transmission. The crew were most likely using high frequency radio waves. These waves are reflected by the earth's ionosphere; hence, over the horizon propagation can be achieved by propagating them towards the sky so that they can be reflected to the destination.
State three examples of unguided transmission media.
Differentiate between Very High Frequency (VHF) and Ultra High Frequency (UHF) radio waves.19/11/2022 Differentiate between Very High Frequency (VHF) and Ultra High Frequency (UHF) radio waves.
VHF waves occupy the space just above the HF waves on the electromagnetic spectrum. Their frequency ranges from 30-300 MHz. They are ideal for short range terrestrial communication. They are easily blocked by obstacles and cannot be directly propagated beyond the horizon, hence the need for repeaters that have line of sight contact. UHF waves, on the other hand, are propagated within a localised region for high quality signal reception than VHF. Their frequency ranges from 300 MHz to 3 000 MHz on the electromagnetic spectrum. Due to their small wavelengths, they require smaller aerials to receive the signal.
State four areas where VHF transmission is used.
State four areas where UHF radio waves are used.
Highlight three categories of radio waves.
Define the term 'unguided transmission media'.Unguided transmission media transmit signals from the source to the destination but do not force the signals to pass through restricted paths. Electromagnetic waves are examples of unguided transmission media. State three examples of unguided transmission media.
Study Table below and match the characteristics in the first column to the cable type by marking with an x in the appropriate column.State five advantages of using fibre optic as a transmission media.
Differentiate between single mode and multimode fibre optic cables.A single mode fibre optic cable has a very thin core hence, it can only receive a single ray of light while a multimode fibre optic cable has a thick core and can receive multiple light rays. Light in the multimode cable attenuates faster than in the single mode. State one application area for each mode of fibre optic cables.
Using an illustration, explain how a fibre optic cable transmits data.Light pulses carrying data are projected into the cable at the source in such a manner that the angle of incidence is greater than the critical angle of the core. The light in the core tries to penetrate the cladding. Since the cladding is of higher refractive index, total internal reflection occurs. The light is kept within the core, bouncing off the boundary of the core and cladding until it reaches to the destination.
Using a diagram, explain the physical structure of a fibre optic cable.The core of a fibre optic cable is made up of transparent glass or plastic. Surrounding the core is a more dense material of higher refractive index than the core called the cladding. The outer protective layer or jacket protects the cable from mechanical harm.
With the aid of a diagram, describe the physical structure of a coaxial cable.Coaxial cables are made up of a central copper core that is insulated with a dialectric material (insulator), an aluminium foil, a braided shield (or mesh conductor) and an outer plastic covering. This insulation makes the cable resistant to electromagnetic interference.
Describe the electrical properties of coaxial cables that made it suitable as a network backbone before the advent of fibre optic cables.Coaxial cables support high bandwidth compared to UTP cables; hence, a preferred choice for laying network backbones. In addition, it conducts data using direct current and is more immune to electromagnetic interference thus it is preferred for EMI prone places.
Using illustrations, differentiate between thinnet and thicknet coaxial cables.A thinnet or thin coaxial cable has one dielectric insulator (Fig. 1.5 (a)) while a thicknet or thick coaxial cable has two dielectric insulators (Fig. 1.5 (b)).
List five sources of electromagnetic interference that may cause data loss in communication systems.19/11/2022 List five sources of electromagnetic interference that may cause data loss in communication systems.
ADVANTAGES OF SETTING UP A COMPUTER NETWORK USING TWISTED PAIR CABLES
Disadvantages OF SETTING UP A COMPUTER NETWORK USING TWISTED PAIR CABLES
State the components needed for each of the following task in a fibre network.
Using illustrations, differentiate between unshielded and shielded twisted pair cables.The two types of twisted pair cables are made up of two insulated copper wires wound around each other to form a helix.
However, the unshielded twisted pair (UTP) cables do not have an external shield to guard against electromagnetic interference (EMI) from the environment as shown in Fig 1.3 (a). Shielded twisted pair (STP) cables, on the other hand, have an external shield which guards against environmental EMI (Fig. 1.3 (b)) Why is the use of the two wire open lines cables not common nowadays.The cables suffer from electromagnetic interference (EMI) because they are not shielded from environmental 'noise'. They pick electromagnetic signals from the environment; hence, they introduce noise in the communication channel. The magnetic fields around individual cables also interfere with each other during transmission leading to high radiation losses through a process called crosstalk.
Describe how the two wire open lines cable works in data transmission.The cable is made up of two copper wires running parallel to each other and separated by a plastic insulator. The copper wires are good signal conductors and are cheap to buy.
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