Reg No.:

Max. Marks: 100

1 a)
b)
2 a)
b)
3 a)
b)
4 ಬ)
b)
5 a)
b)
6 a)
b)
7 2)
b)

B4E0572

Total Pages: 2

Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FOURTH SEMESTER B.TECH DEGREE EXAMINATION, JULY 2017
Course Code: EC208
Course Name: ANALOG COMMUNICATION ENGINEERING (EC)

PARTA
Answer any 2 questions. Question No.1 is compulsory.
Starting from the representation of sinusoidally modulated AM wave: -
i) Find the frequency spectrum for sinusoidal AM
ii) Derive the equation for total transmitted power
Give reason for the occurrence of double spotting in AM receivers.
Draw the block diagram and explain the working of a low-level AM transmitter.
A transmitter with a LOKW carrier transmits 11.2 KW when modulated with a
single sine wave: -
i) Calculate the modulation index.
ii) If the carrier is also simultaneously modulated with another sine wave at 50%
modulation, calculate the total transmitted power
OR
Explain the working of a diode detector for AM demodulation with diagrams.

A 12 GHz receiver consists of first stage with gain G1 =30 dB and noise temperature
11 =20 1९, a second stage with gain G2 = 10 dB and noise temperature T2 = 360K
and third stage with gain G3 = 15 dB and noise temperature T3 = 1000 K. Calculate
the effective noise temperature and noise factor of the system. Take the reference
temperature as 290 K.
PART 13

Answer any 2 questions. Question No.4 is compulsory.
With block diagram, explain the working of a super heterodyne receiver and list
their advantages.
Write the advantages of double conversion receiver.

With neat block diagram, explain the generation of SSB using phasing method.

Explain the factors that affect the sensitivity and selectivity of a super heterodyne
receiver.
OR
With block diagram, explain the working of a balanced modulator circuit using
FETs, for the generation of double sideband suppressed carrier.
Compare the merits and demerits of AM and FM.
PART C
Answer any 2 questions. Question No.7 is compulsory.
With a block diagram, explain the FM demodulator using PLL.

Explain with diagrams, how the response of parallel tuned circuit is made use for
the demodulation of FM.

Page 1 of 2

Duration: 3 Hours

(10)

(5)
(10)
(5)

(10)
(5)

(10)

(5)
(10)
(5)

(10)

(5)

(10)
(10)