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UNIT - IV

CDMA

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CDMA

The carrier is modulated in the normal way by the information waveform and then is

further modulated by the code waveform to spread the spectrum over the available rf

bandwidth.

Many of the key properties of CDMA rely on this spectrum spreading, and the systems

employing CDMA are also known as spread-spectrum multiple access !!MA".

The code waveform ct" is also a polar #$% signal. &'!( signal carries both the

information signalpt" and the code signal ct". This method is referred to as direct-

sequence spread spectrum D!)!!".

*ther techni+ues are also used to spread the spectrum, such as fre+uencyhopping.

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CDMA System

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sequence code

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Acquisition of a carrier

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Delay Lock Loop

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Spreading and Despreading

Th H i " d # i

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The Home ecei!er "utdoor #nit$"D#%

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US-DBS systems

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