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information-technical.html
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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<link href="css/digital.css" rel="stylesheet" type="text/css"></link>
<style type="text/css">
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</style>
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<body class="indy">
<img class="indy" src="images/technical.jpg"></img>
<br></br>
<div class="menus">
<a class="a3" href="information.html">Summary</a><b class="b1">  |  </b><a class="a3" href="information-technical.html">Technical Details</a><b class="b1">  |  </b><a class="a3" href="references.html">References</a><b class="b1">  |  </b><a class="a3" href="links.html#information">Links</a>
</div>
<div class="indy">
Information is defined as facts or knowledge that are provided or learned.
<br></br>
Communication of information has occurred since the very first human settlements ever existed. It is an important ability that humans possess and it is a phenomenon that is studied by scientists, philosophers and psychologists alike. Digital communication has developed worldwide since the understanding of the Laws of Electrodynamics, a theory created by James Clerk Maxwell based on work by Rudolf Heinz Hertz. The use of these four laws thus lead to the creation and use of radio waves, and a short step away was the creation of the very first wireless transmitted created by Marconi in 1894 using a spark gap transmitter and a coherer for the reception of signals. Wireless communication continued to evolve through the 20th Century and has developed into television, and digital transmission and the mobile phone culture that we have now, and modern communications methods take advantage of a mixture wireless technologies, satellite t echnologies, radio and the hard-wired telephone network infrastruc ture.
<br></br>
An important concept of information is that it is communicated effectively. If it took a large number of seconds to communicate sentences such as yes or no, or watch out, then difficulties could arise for everyone. In terms of the speeds of communication nowadays it seems rather insignificant, but in terms of technologies such as the Internet, effective coding techniques are paramount.
<br></br>
Information theory developed by Claude Shannon in 1948 helps to outline the idea of working out the amount of information in a message and the most effective way to communicate that information. It is possible to analyse the amount of bits of data that is required to be sent against a single bit of information, this is called the measured entropy of a message, it is the measure of information content in bits.
<br></br>
Effective use of this theory helps us to achieve optimal communications techniques for the technology that we have available. Morse code developed in 1835 is considered as a entropy encoded communications technique as although it was developed in the early half of the 19th Century it uses a variable length coding technique using short codes for frequent letters such as 'a' and 'e' and longer codes for less frequent letters such as 'z' and 'q'.
<br></br>
Modern coding and compression techniques of digital data allow for effective digital communication techniques in similar ways to the entropy coding of Morse code but also incorporating new techniques that have been developed to aid in the effective and efficient communication of information.
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Two categories of coding exist, lossy coding and lossless coding. Lossy coding formats involve removing redundant information within messages. Such a technique is MP3 encoding. The MP3 coding process removes frequencies of sounds that are inaudible to the human ear. The sounds appear in the frequency domain between 2.5KHz and 5Khz. As the name suggests once this information is removed it is lost, and the data can never be represented in the same way again.
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This is in contrast to the lossless coding such as those employed in PNG images, and ZIP archives. Lossless coding techniques use special algorithms that optimise the data within a message. LZW is an example of a lossless coding technique, it is a dictionary-based method of compression that looks for pairs of strings within the data and stores them together within the dictionary. The only data then sent over the communications link is the dictionary. An effective decompression algorithm is what allows this dictionary to be analysed and used to construct the data in its original form. No information is lost within lossless coding as data can be compressed and decompressed without removing any data.
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As looked at within an earlier section of this portfolio mobile phones convert analogue voice signals ultimately into digital pulses and then back again to allow voice communications. Mobile phone communication can be improved by adding compression techniques into this conversion process. Before converting the analogue signal into a binary representation extraneous frequencies that represent white noise are removed from the voice signal to clean it up. This reduces the amount of information that needs to be communicated but it also aids in the effective use of error correction when the data is received at the other end.
<br></br>
The Internet is making more use of compression techniques as communications using it are expensive, even creators of HTML files need to observe good programming practices to remove white space and redundant information from the file as bandwidth is limited and it is necessary to communicate as much information possible with the least number of bits. Compression techniques are therefore used to achieve this in areas where simple good programming practices cannot be applied such as the creation and transmission of image files such as JPEG, which depending on the particular JPEG file type used can either be a form of lossy or lossless coding.
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<p class="signature" align="right">rs</p><br></br>
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<p class="copy">© MMV</p>
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