DR.
BABASAHEB AMBEDKAR TECHNOLOGICAL UNIVERSITY, LONERE
Supplementary Summer Examination – 2024
Course: B. Tech. Semester : V
Branch : Electronics and Telecommunication Engineering / Electronics and Communication Engineering
Subject Code & Name: BTETC503 - Analog Communication
Max Marks: 60 Date: 05/07/2024 Duration: 3 Hr.
Instructions to the Students:
1. All the questions are compulsory.
2. The level of question/expected answer as per OBE or the Course Outcome (CO) on
which the question is based is mentioned in ( ) in front of the question.
3. Use of non-programmable scientific calculators is allowed.
4. Assume suitable data wherever necessary and mention it clearly.
(Level/CO) Marks
Q. 1 Solve Any Two of the following. 12
A) Define Modulation. Explain need of modulation in detail. CO01 6
B) State sampling theorem. Explain sampling process in detail. A message signal CO01 6
made of multiple frequency components: a single tone sine wave of 850 kHz
and sound of frequency components with lowest value of 500 Hz and highest
value of 2700 Hz. Calculate he minimum sampling frequency to sense the
information present in this signal according to sampling theorem.
C) Explain following terms: CO01 6
(a) simplex system, (b) duplex system,
(c) point to point communication, (d) broadcast communication,
(e) TDM, (f) FDM.
Q.2 Solve Any Two of the following. 12
A) Explain generation of SSB signal using (i) the filter method and (ii) the phase CO02 6
shift method.
B) Explain Vestigial Sideband (VSB) modulation techniques along with its CO02 6
advantages and disadvantages.
C) A 750 W carrier is amplitude modulated to the depth of 75%. Calculate the CO02 6
total power in case of (i) DSB-SC, (ii) SSB-SC, (iii) ISB and (iv) VSB (with
25% of other sideband). Also find power saving compared to DSB-FC for
each case.
Q. 3 Solve Any Two of the following. 12
A) Explain frequency modulation. Also find mathematical expression for CO05 6
(i) maximum frequency deviation, (ii) instantaneous value of FM voltage.
B) State the difference between AM, FM and PM. CO05 6
C) In a PM system, when the audio frequency (AF) is 550 Hz, and the AF voltage CO05 6
is 3.2V, the deviation is 3.6 kHz. If the AF voltage is now increased to 7.2 V,
what is new deviation? If the AF voltage is further raised by 7V while the AF
is dropped to 175 Hz, what is the deviation? Find modulation index in each
case.
Q.4 Solve Any Two of the following. 12
A) Enlist different types of radio receiver. Explain any one in detail with the help CO03 6
of block diagram.
B) Briefly explain any four performance characteristic of a radio receiver. CO03, 04 6
C) Explain double spotting with its cause and effect. Explain how it can be CO04 6
reduced.
Q. 5 Solve Any Two of the following. 12
A) Explain operation of ratio detector. Also explain how amplitude limiting can CO03 6
be achieved using ratio detector
B) Define noise. Explain its various types in communication system. CO06 6
C) a) Define (i) signal to noise ratio and (ii) noise figure. CO06 6
b) A receiver connected to antenna whose resistance is 80 has an
equivalent noise resistance of 45. Calculate the receiver’s noise figure
in decibels and its equivalent noise temperature.
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