7/17/2019 3ece AnalogCommunications MID-1

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1a) Explain the Nonlinear method of  AM  signal generation with necessary equations. [3M]

) !n  AM   signal is gi"en y

s ( t )=10cos (2π . 106

t  )+5cos (2 π .106

t  )cos (2π . 103

t  )+2cos (2 π .106

t )cos (4 π .3 t ) volts . (i)#raw the line

spectrum and find andwidth. (ii)$alculate net modulation index.[%M]

%a) Explain demodulation of DSB-SC signal using synchronous method and give the

mathematical analysis of synchronous detection.[&M]

) 'n a #(*($ system the modulating signal is single tone sinusoid10cos(2π .10 t )

+ which modulates a carrier signal

10cos (2π .1000 t ) ). ,lot the spectrum of the modulated wa"e- [1M]

3a) !n  AM-SSB signal is generated y modulating an 800 KHz  carrier y the signalm (t  )=cos (2000πt  )+2. si n (2000 πt )

.he

amplitude of unmodulated carrier is 100V . #etermine (i) the ime domain expression for the /pper side and of the SSB  signal.

(ii)#etermine its magnitude spectrum. [3M]

) 0ith a neat loc diagram explain the generation of SSB-SC  modulated signal using phase discrimination method.[%M]

&a) Explain the $ostas loop method of carrier acquisition and demodulation of  DSB-SC  wa"e. [3M]

) Explain the operation of En"elope detector for the detection  AM  modulated wa"e. 0hat is the condition for a"oiding

en"elope distortion- [%M]

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