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  • Level: GCSE
  • Subject: ICT
  • Word count: 2566

Distinguish between analogue and digital signaling and describe the role of a modem in computer communications.

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Introduction

Task 1: Distinguish between analogue and digital signaling and describe the role of a modem in computer communications. Analogue Signaling As a technology, analogue is the process of taking an audio or video signal and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s. Simple enough when it's the device-analogue or digital phone, fax, modem, or likewise-that does all the converting for you. Analogue technology has been around for decades. It's not that complicated a concept and it's fairly inexpensive to use. That's why we can buy a R100 telephone or watch a few TV stations with the use of a well-placed antenna. The trouble is, analogue signals have size limitations as to how much data they can carry. So with our R100 phones and inexpensive TVs, we only get so much. Amplitude Amplitude is the strength of an analogue signal i.e. the higher the amplitude the stronger the signal. Amplitude is usually measured in decibels, but can also sometimes be measured in volts. Frequency Frequency is the rate of change in which an analogue signal undergoes each second. It can also be described as the number of vibrations each second. It is measured in Hertz. For example the signal of a man's voice vibrates less times per second than a woman's; hence it has a lower frequency. ...read more.

Middle

The main drawback of this topology stems from the fact that usually only one communications channel exists to service the whole network. If this channel fails then the whole network may fail. Some vendors provide spare channels for use in the event of channel failure, and others may provide switches that allow the channel to be routed around failed nodes. Star Topology The star topology is another widely used structure for data communications systems. One of the major reasons for its continued use is based on historical precedence. The star network was predominant in the 1960s and early 1970s because it was easy to control. An example star network is shown in figure below. Example of a star network topology All traffic emanates from the hub of the star. The central site in figure above, labelled A, is in control of all the DTEs attached to it. The central hub is usually a self contained computer and is responsible for routing all traffic to other DTEs and fault isolation. However, like the hierachical structure, this type of network is also prone to bottleneck and failure problems at the central site. Several star networks developed in the 1970s had serious reliability problems because of the centralised nature of the network. Other systems attempted to solve this problem by providing a redundant backup of the hub node. Ring Topology The ring topology is another popular approach to configuring networks. As illustrated below the ring topology is so named because of the circular aspect of the data flow. ...read more.

Conclusion

to the wide-area network (WAN) of the Internet. By maintaining configuration information in a piece of storage called the "routing table," routers also have the ability to filter traffic, either incoming or outgoing, based on the IP addresses of senders and receivers. Some routers allow the home networker to update the routing table from a Web browser interface. DSL and cable modem routers typically combine the functions of a router with those of a switch in a single unit. Task 7: Distinguish between the Internet and the World Wide Web and describe a rabge of services they provide The Internet and the Web are related, but are really two separate things. The Internet is the collection of all computers and networks that carry and transmit information, based on telecommunications protocols. The Web is based on one of these protocols known as HTTP (Hypertext Transfer Protocol). In simple terms the Web is the collection of documents and information that are held on, and sent through, the Internet. The internet is a much larger thing than the World Wide Web. Basically, the internet is a term which can be applied to any and every thing working on IP, which means internet protocol. IP is a system of standards of communication between computers which has been developing along with the internet. It provides a common basic language for each of the many types of machines connected to the internet. The internet includes the devices which transmit and receive data, the devices which help route data, and the physical media which carry the data from place to place, and even the data itself. Stevan Burrows Communications Technology Assignment ...read more.

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