Model question paper of Analog Communications of Diploma 3rd Sem - E & CE

   DERARTMENT OF TECHNICAL EDUCATION
DIPLOMA COURSE IN ELECTRONICS & COMMUNICATION ENGG.
THIRD SEMESTER
       
MODEL QUESTION PAPER

ANALOG    COMMUNICATION

MAX MARKS:100                                                               TIME :3Hrs

       
INSTRUCTIONS:-
1    SECTION-I IS COMPULSORY   
2    ANSWER ANY TWO FULL QUESTIONS FROM EACH OF THE REMAINING    
    SECTIONS.
   

SECTION   I

1 A)    FILL IN THE BLANKS WITH APPROPIRATE WORDS:-    1X5
I)    The current at Resonance in Series Resonance circuit is____________.
ii)    The cut off frequency of LPF is given by ____________.   
iii)    The  Attenuator is a  __________Network.
iv)    The characteristic impedance of transmission line is given by_________.   
v)    The modulation index in FM is given by___________.        
       
B)    Write a  note  on Equalizers.                                                            5
       

SECTION :II

2 a)    State  Superposition theorem .    3
   b)    List the steps involved in simplifying the network using the Superposition
          theorem.    5
Define Resonance . Derive the expression for Resonant frequency of Parallel    
       Resonance  circuit.                               7
       
3 a)    Derive the expression for L and C of constant K – T section LPF.    7
b)    Design  constant K - PI section HPF given fc= 2 KHz , Ro= 600 ohms.    5
c)        Find the relationship between  Decibel and Neper.    3
   
4a)    Define Attenuator and mention its Applications.     4
b)    Design   T –type attenuator  given attenuation =10 dB , Ro= 600 ohms.           5
c)          State Norton’s Theorem and write its Equivalent circuit.    6

SECTION :III

5a)    Describe the electrical model of Transmission line..      4
  b)        Explain the following :                       
           (a) Reflection and (b) Standing waves in Transmission Line.      4                           
c)        Derive the Relationship between SWR and Reflection Coefficient.      7  

6  a)   Define the following terms w.r.t Antenna :                       
               (a) Polarization,                            
               (b) Isotropic radiator                           
               (c) Radiation pattern                            
               (d) Directive gain                           
               (e) Directivity                                       10
b) Explain the working of broadside  array.               5
                                
7 a)     Explain  Single stub matching .                       5 
b)     Explain  Ground wave propagation with relevant diagram.     6                   
   c)     Explain propagation in a mobile/portable environment .        4                                    

SECTION : IV

8a)    Explain the need for Modulation.      4
b)    Explain amplitude modulator circuit using diode.         5
c)       Sketch the FM wave. Write mathematical expressions for the following:               
              (a) Frequency deviation                       
              (b) Modulation index              6     
                 
9a)    Explain the working of AM Linear diode detector circuit.          5
b)        Explain the working of Foster Seeley discriminator .               6   
c)    Explain the need for pre-emphasis and de-emphasis circuits.       4
       
10a)     Explain the working of High level  AM transmitter with a neat block diagram.  8     
    b)     Explain the working of FM receiver with Block Diagram.         7