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A method of achieving the spreading of a given signal is provided by the modulation scheme. With DSSS, the message signal is used to modulate a bit sequence known as a [[Pseudorandom noise#PN code|Pseudo Noise (PN)]] code; this PN code consists of a radio pulse that is much shorter in duration (larger bandwidth) than the original message signal. This modulation of the message signal scrambles and spreads the pieces of data, and thereby resulting in a bandwidth size nearly identical to that of the PN sequence.<ref name=Haykin4E/> In this context, the duration of the radio pulse for the PN code is referred to as the [[Chip (CDMA)|chip]] duration. The smaller this duration, the larger the bandwidth of the resulting DSSS signal; more bandwidth multiplexed to the message signal results in better resistance against interference.<ref name=Haykin4E/><ref>{{Cite web|url=http://www.telecomabc.com/d/dsss.html|title=DSSS - Direct Sequence Spread Spectrum - Telecom ABC|website=www.telecomabc.com|access-date=2016-11-11}}</ref>
Some practical and effective uses of DSSS include the [[Code Division Multiple Access]] (CDMA) [[channel access method]] and the [[IEEE 802.11#802.11b|IEEE 802.11b]] specification used in [[Wi-Fi]] networks.<ref name=TRappaport>{{cite book|last1=Rappaport|first1=Theodore|title=Wireless Communications Principles and Practice|date=January 2010|publisher=Prentice-Hall, Inc|page=458|edition=2|url=http://www.pearson.ch/1471/9780130422323/Wireless-Communications-Principles-and.aspx|accessdate=11 April 2015}}</ref><ref>{{Citation|last=|first=|title=Capacity, Coverage and Deployment Considerations for IEEE 802.11G|url=https://people.cs.clemson.edu/~westall/851/802.11/80211_wp.pdf|volume=|pages=1|year=2005|publisher=Cisco Systems, Inc}}</ref>
==History==
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