Download AKTU B-Tech 8th Sem 2014-15 ECS 084 Cryptography And Network Security Question Paper

Code: 20A3301

II B. Tech I Semester (R20) Regular Examinations November 2021

SIGNALS AND SYSTEMS

(ECE)

Time: 3 hours Max. Marks: 70

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Note: 1. Question paper consists of two parts (Part-A and Part-B)

2. Answer ALL the question in Part-A

3. Answer any THREE Questions from Part-B

PART – A (10 x 2 = 20 Marks)

1. Define Signal and System. Give examples.
2. Explain the properties of the unit impulse function.

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3. State the Dirichlet’s conditions for Fourier series.
4. Write short notes on Gibbs phenomenon.
5. Define Laplace Transform and Region of Convergence (ROC).
6. List the properties of ROC of Laplace Transform.
7. Define Z-Transform.

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8. Write the relation between Laplace, Fourier and Z-transforms.
9. Define cross correlation and auto correlation.
10. Define energy spectral density and power spectral density.

PART – B (3 x 16 = 48 Marks)

11. a) Explain orthogonality between two signals f1(t) and f2(t) over an interval t1=t=t2. [8M]

    b) Determine whether the following signals are periodic or not. If periodic, find the fundamental time period. [8M]

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    1. x(t) = 2cos(t/4) + 6sin(t/3)
    2. x(t) = cos(p/3 t) + sin(p/4 t)

12. a) Determine the Fourier series representation of the signal x(t) = 2t, 0

    b) State and prove differentiation and integration properties of Fourier Transform. [8M]

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13. a) Find the Laplace transform of f(t) = te^-2tu(t). [8M]

    b) Find the inverse Laplace transform of F(s) = 1/(s(s+1)). [8M]

14. a) Find the Z-transform of x(n) = aⁿu(n). [8M]

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    b) State and prove the properties of Z-transforms. [8M]

15. a) Derive the relation between input and output of an LTI system. [8M]

    b) Find the autocorrelation of the signal x(t) = A cos(?t). [8M]

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