INTERNAL 1 QUESTION PAPER FOR COMMUNICATION THEORY

SRI SUBRAMANYA COLLEGE OF ENGINEERING AND TECHNOLOGY

Internal Test –I (2014-15)

              Department of Electronics and Communication Engineering 

Date         : 11.02.2015                                                              Duration: 1 hr 30 min

Subject     : EC6402 Communication theory                  Name of the Staff: Mr. M. Marimuthu

Year/Sem : II year / IV Sem                                           Marks: 50 marks

               

 Part - A                                        Answer all the question                          (7*2=14)

1. Why is frequency modulation preferred for voice transmission?

2. If the maximum phase deviation in a PM system is 0.1 radian when a modulating signal  

     is applied is 10V. Determine the value of phase deviation constant.

3. What is the need for pre emphasis?

4. Define frequency discriminators

5. What is meant by amplitude modulation?

6. Why do we need modulation?

7. Determine the range of tuning oscillator of a super heterodyne receiver when f_Lo > f_c.

    The broad cast frequency is 540 Hz to 1600 Hz. Assume: f_if=455 KHz

 Part –B                                  Compulsory Question                                               (1*4=4)

8. Draw the simple schematic of a PLL demodulator     

  Part – C                                Answer any 2Questions                                            (2*16=32)

9    (i) Derive an equation for single tome FM signal                                           (6)

      (ii) Derive an expression for spectrum of FM signal using Bessel function   (10)

10  (i) With neat diagram explain Armstrong method of generating FM signal. (10)

      (ii) Mention any 5 points to differentiate AM from FM wave                       (6)

11.  (i) Explain the working of super-heterodyne receiver with diagram             (8)       

      (ii) Explain in detail about modulation and demodulation of VSB               (8)

*** All The Best ***