| COMMUNICATION SIGNAL AND SYSTEMS |
| PAPER NO. 3 |
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| PUT ON: June 2K2 |
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EC-202 COMMUNICATION SIGNAL AND SYSTEMS (B.Tech 4th Semester,2052) Time : 3 Hours Maximum Marks : 60 NOTE:- This paper consist of Three Sections. Section A is compulsory. Do any Four questions from Section B and any two questions from Section C Section-A Marks : 20 1(a) Classify basic signals and systems. (b) Define Fourier transform. (c) Draw the waveform for a sin c function. (d) Differentiate between joint and conditional probability. (e) What ia an Ergodic process? (f) Define convolution theorem. (g) Define noise figure. (h) What are various sources of noise in a Bipolar transistor ? (i) Explain sampling theorem. (j) Draw a normalized Guassian Distribution function. Section-B Marks:5 Each 2. Evaluate the Fourier transform of the damped sinusoidal wave g(t) = exp(t) sin (2πfct) u(t), where u(t) is the unit step function. 3. The Fourier transform of signal g(t) is denoted by G(f). Prove that:  f(x) = K/1 + x2 -∞ <= x <= ∞. (a) Find K so that f(x) is a density function. (b) Find E(X). 5. Specify the Nyquist rate and the Nyquist interval for each of the following signals: (a) g(t) = sin c(200 t). (b) g(t) = sin c (200 t) + sin2c (200 t). 6. Calculate the noise voltage at the input of T.V. RF Amplifier, using a device that has a 200 ohm equivalent noise resistance and a 300 ω input resistor. The B.W. of the amplifier is 6 MHz. and the temperature is 17o C. Section-C Marks : 10 Each 7. A perodic triangular waveform is defined by: v(t) = 2t/T for -T/2 < t < T/2 and v(t+- T) = v(t). Find the Fiurier transform of the periodic triangular pulse. 8. A coin is tossed untill a head appears. Let T be the random variable which identifies the no. of tosses t required for the appearance of the first head. Make a plot of the probability P ( T<= t) as a function of t up to t = 5. 9. Write short notes on: (a) BURST NOISE (b) MATCHED FILTER. |
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