Dr. A.P.J. Abdul Kalam University BE IV SEM (EC) Communication Systems [EC227T] June 2021 Question Paper

Dr. A.P.J. Abdul Kalam University

Bachelor of Engineering

Forth Semester Main Examination, June-2021

Communication Systems [EC227T]

Branch-EC

Time: 3:00 Hrs Max Marks 70

Note: (i) Attempt any five questions. All questions carry equal marks.

(ii) Answer should be precise & to be point only.

(iii) Assume suitable data if necessary & state them clearly

Q.1 (a) Explain properties of Impulse function?

(b) Find the Fourier transforms of the following functions and sketches them

(a)sgn(t) (b) rect(𝑡𝑇)

 Q.2 (a) State and prove time shifting property and frequency shifting property of

Fourier transform?

(b) Explain generation method of A.M using square law modulator with the

help of suitable diagram?

 Q.3 (a) With the help of circuit diagram, explain the working of balanced

modulator for DSB-SC generation?

(b) Explain the synchronous detection method of DSB-SC signals?

Q.4 (a) Write a short on VSB modulation and demodulation?

(b) Explain the function of super heterodyne receiver. Write down its

advantages and disadvantages?

Q.5 (a) What is tunnel radio receiver?

(b). Explain noise in Amplitude modulation?

Q.6 (a) What do you understand by angle modulation? Explain the types of angle

modulation?

(b) Explain block diagram of FM transmitter and receiver?

Q.7 (a) Explain narrow band FM and wide band FM?

(b) Write short on AGC? Draw the block diagram of broadcast receiver

using AGC?

Q.8 (a) Explain classification of noise in FM signals?

(b)Explain effect of noise in FM and AM receiver?

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