ALAGAPPA CHETTIAR COLLEGE OF ENGINEERING & TECHNOLOGY, KARAIKUDI- 630 003 Department of Electronics and Communication Engineering Third Semester Internal Assessment –3 19ECG31 – SIGNALS AND SYSTEMS Duration: 90min Date: 11-12-2020 Maximum Marks : 50 Answer ALL the Questions Part – A (92=18 Marks) CO4: CO4: CO4: CO4: CO4: CO5: CO5: CO5: CO5: 1. State Sampling theorem. 2. What is Z-Transform and the associated ROC of the signal x(n)=u(n-n0)? 3. Consider the analog signal xa(t)=5cos50πt+2sin100πt-2cos100πt. Determine the minimum Sampling frequency of the signal. 4. How the aliasing process eliminated? 5. Perform circular convolution of the two sequence x1(n)={2,1,2,1} and x2(n)={1,2,3,4}. 6. Define discrete time Fourier transforms. 7. State the time shifting property of Z-transform. 8. Define BIBO stability. 9. Determine the transfer function of the system described by the given state model. q(n+1)= -2q(n)+0.5x(n); y(n)=0.7q(n). Part – B (2×16 = 32 Marks) CO4: 10. i. ii. CO4: CO5: 11. 12. Explain how a band limited signal can be sampled without aliasing? Find DTFT of the signal x(n)=(0.2)nu(n)+(0.2)-nu(-n-1). (8) (8) i. (Or) Find the Z-transform of the signal x(n)=(2/3)nu(n)+(-1/2)nu(n) and find ROC. (8) ii. Using residue methods find the inverse Z-transform of i. H(z)=(1+3z-1)/(1+3z-1+2z-2) , Z>2 (8) Construct block diagram of the discrete time system whose input- output relation is described by the difference (8) equation y(n)=3.2x(n-2)+0.7x(n)+5y(n-1)+0.35y(n-2) ii. Find the state variable matrices A,B,C,D for the equation CO5: 13. i. ii. y(n)-3y(n-1)-2y(n-2)=x(n)+5x(n-1)+6x(n-2) (Or) Explain about state vector, state space and output space of a discrete time system. (8) (6) A causal system is represented by the difference equation y(n)+1/4y(n-1)=x(n)+1/2x(n-1). Find the system transfer H(z), the impulse response and frequency response of the system. Prepared By M.Aruna Rani, AP / ECE HOD / ECE