1)Explain the need of analog and digital modulation incommunication systems.
2)How modulated signals can be recovered through coherent detectionof carrier. Draw suitable diagram and mathematical expressions.Whatis meant by over modulated carriers.
3)Drive an expression for transmission efficiency of A.M wave.Under what circumstances carrier wave reversal take place.
4)How SSB-SC modulated waves can be produced. Elaborate your answerwith suitable diagram.
5)A device is sending out data at the rate of 1000 bps.
(a) How long does it take to send out 10 bits?
(b) How long does it take to send out a single character (8bits)?
(c) How long does it take to send a file of 100,000 bits.
     6) What is relationship between phase andfrequency modulation .Write complete mathematical expression anddiagrams.
      
       7) For a continues timesignal                   [CLO-3]
              X(t)=8cos 200πt
a)Determine the nyquist rate required to avoid aliasing.
b)If sampling frequency f=500 Hz , what is discrete time signalx(n)qx(nTs) obtained after sampling.
8) Figure shows periodic rectangular wave form. Find its Fourierseries representation.[CLO-3]

9) Determine the nyquist sampling rate and intervalfor following signals.[CLO-3]