Difference between pages "Global System for Mobile Communications" and "AAC"

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The '''Global Systems for Mobile Communications''' ('''GSM'''), is a radio-based technology that allows [[mobile phones]] to communicate. GSM is considered to be the world's most ubiquitous radio-based cellular technology, with 1.7 billion users as of March 2006. In the United States, carriers such as [[T-Mobile]] and [[Cingular]] utilize GSM technology for their cellular networks.
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The '''Advanced Audio Coding''' ('''AAC''') file format is a lossy digital audio encoding format. Files downloaded from the [[iTunes Music Store]] are available in this format.
  
= GSM Cell Phone Providers =
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== Metadata ==
  
== USA ==
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AAC files usually have a file ending of [[M4P|.m4p]] and contain lots of [[metadata]]. The output of the [[Unix]] [[strings]] command suggests that at least the following information is contained:
  
* [[Cingular]]
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* Name of the person who downloaded the file from the [[iTunes Music Store]]
* [[T-Mobile]]
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* Email address of that person (sometimes)
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* [[Timestamp]] of when the file was downloaded
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* Another timestamp (probably the date when the file was put into the [[iTunes Music Store]]?)
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* The usual metadata of music files (artist, album, cover art etc.)
  
== Other ==
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== External Links ==
  
* [[T-Mobile]]
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* [http://en.wikipedia.org/wiki/Advanced_Audio_Coding Wikipedia: AAC]
* [[Vodafone]]
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* [[O2]]
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= Operational Characteristics =
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== Network Principles ==
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GSM is considered to be 2G and uses digital data for both signaling and voice purposes. GSM uses a time division multiple access ([[TDMA]]) protocol to transmit information. Aside from voice, [[GPRS]] and [[EDGE]] allow for data transmissions across a GSM network.
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== Radio Communication ==
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In terms of frequencies used, GSM networks often use the 900MHz and 1800MHz bands, but carriers in the United States use 850MHz and 1900MHz bands. As a result, "dual-band" phones, which only support two of the four major bands, can only be used in certain parts of the world. More common are "tri-band" phones, which usually operate on 900/1800MHz and 1900MHz. "Quad-band" phones support all four frequencies and can be used in all parts of the world.
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== Security and Encryption ==
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* [[SIM Card]]
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* [[Security Standards]]
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* [[Authentication Standards]]
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== GSM Forensics ==
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* [[Phone with SIM Card]]
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* [[Phone without SIM Card]]
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* [[SIM Card]]
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== External Links ==
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* [http://www.gsmworld.com/index.shtml GSM World]
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[[Category:File Formats]]

Latest revision as of 13:20, 3 May 2006

The Advanced Audio Coding (AAC) file format is a lossy digital audio encoding format. Files downloaded from the iTunes Music Store are available in this format.

Metadata

AAC files usually have a file ending of .m4p and contain lots of metadata. The output of the Unix strings command suggests that at least the following information is contained:

  • Name of the person who downloaded the file from the iTunes Music Store
  • Email address of that person (sometimes)
  • Timestamp of when the file was downloaded
  • Another timestamp (probably the date when the file was put into the iTunes Music Store?)
  • The usual metadata of music files (artist, album, cover art etc.)

External Links