The GATE Grind

GATE Networks, Signals and Systems: Discrete-time Signals – Previous Year Questions

25 GATE previous year questions on Discrete-time Signals (Networks, Signals and Systems, Electronics and Communication Engineering) with answers and explanations, from every paper.

  1. GATE 2017 EC Q42 (2 marks, Numerical answer) – Two discrete-time signals x[n] and h[n] are both non-zero only for n = 0, 1, 2, and are zero otherwise. It is given that x[0] = 1, x[1] = 2, x[2] = 1,…
  2. GATE 2017 EC Q43 (2 marks, Numerical answer) – Let h[n] be the impulse response of a discrete-time linear time invariant (LTI) filter. The impulse response is given by h[0] = 13; h[1] = 13; h[2] =…
  3. GATE 2015 EC Q53 (2 marks, Multiple choice) – Two sequences [a, b, c] and [A, B, C] are related as, bmatrix A \\ B \\ C bmatrix = bmatrix 1 & 1 & 1 \\ 1 & W 3-1 & W 3-2 \\ 1 & W 3-2 & W 3-4…
  4. GATE 2015 EC Q54 (2 marks, Multiple choice) – For the discrete-time system shown in the figure, the poles of the system transfer function are located at
  5. GATE 2015 EC Q55 (2 marks, Multiple choice) – The pole-zero diagram of a causal and stable discrete-time system is shown in the figure. The zero at the origin has multiplicity 4. The impulse…
  6. GATE 2016 EC Q17 (1 mark, Multiple choice) – A continuous-time function x(t) is periodic with period T. The function is sampled uniformly with a sampling period T s. In which one of the following…
  7. GATE 2016 EC Q18 (1 mark, Multiple choice) – Consider the sequence x[n] = an u[n] + bn u[n], where u[n] denotes the unit-step sequence and 0 < a < b < 1. The region of convergence (ROC) of the…
  8. GATE 2016 EC Q45 (2 marks, Numerical answer) – Consider the signal x[n] = 6[n+2] + 3[n+1] + 8[n] + 7[n-1] + 4[n-2]. If X(ej) is the discrete-time Fourier transform of x[n], then 1 - X(ej)2(2) \, d…
  9. GATE 2018 EC Q23 (1 mark, Multiple choice) – A discrete-time all-pass system has two of its poles at 0.250 and 230. Which one of the following statements about the system is TRUE?
  10. GATE 2018 EC Q65 (2 marks, Numerical answer) – Let X[k]=k+1, 0 k7 be 8-point DFT of a sequence x[n], where X[k]= n=0N-1x[n]e-j2 nk/N. The value (correct to two decimal places) of n=03x[2n] is .
  11. GATE 2019 EC Q13 (1 mark, Multiple choice) – Let H(z) be the z-transform of a real-valued discrete-time signal h[n]. If P(z)=H(z)H(1z) has a zero at z=12+12j, and P(z) has a total of four zeros,…
  12. GATE 2019 EC Q38 (2 marks, Multiple choice) – Consider a six-point decimation-in-time Fast Fourier Transform (FFT) algorithm, for which the signal-flow graph corresponding to X[1] is shown in the…
  13. GATE 2019 EC Q39 (2 marks, Multiple choice) – It is desired to find a three-tap causal filter which gives zero signal as an output to an input of the form x[n]=c 1(-j n2)+c 2(j n2), where c 1 and…
  14. GATE 2019 EC Q54 (2 marks, Numerical answer) – Let h[n] be a length-7 discrete-time finite impulse response filter, given by h[0]=4,\ h[1]=3,\ h[2]=2,\ h[3]=1,\ h[-1]=-3,\ h[-2]=-2,\ h[-3]=-1, and…
  15. GATE 2020 EC Q24 (1 mark, Multiple choice) – Which one of the following pole-zero plots corresponds to the transfer function of an LTI system characterized by the input-output difference equation…
  16. GATE 2020 EC Q39 (2 marks, Multiple choice) – A finite duration discrete-time signal x[n] is obtained by sampling the continuous-time signal x(t)=(200 t) at sampling instants t=n/400, n=0,1,,7.…
  17. GATE 2020 EC Q63 (2 marks, Numerical answer) – The transfer function of a stable discrete-time LTI system is H(z)=K(z-)z+0.5, where K and are real numbers. The value of (rounded off to one decimal…
  18. GATE 2021 EC Q15 (1 mark, Multiple choice) – Consider two 16-point sequences x[n] and h[n]. Let the linear convolution of x[n] and h[n] be denoted by y[n], while z[n] denotes the 16-point inverse…
  19. GATE 2021 EC Q51 (2 marks, Numerical answer) – Consider the signals x[n]=2n-1u[-n+2] and y[n]=2-n+2u[n+1], where u[n] is the unit step sequence. Let X(ej) and Y(ej) be the discrete-time Fourier…
  20. GATE 2022 EC Q55 (2 marks, Numerical answer) – For a vector x=[x[0],x[1],,x[7]], the 8-point discrete Fourier transform (DFT) is denoted by X=DFT( x)=[X[0],X[1],,X[7]], where X[k]=…
  21. GATE 2023 EC Q47 (2 marks, Multiple choice) – Consider a discrete-time periodic signal with period N=5. Let the discrete-time Fourier series (DTFS) representation be x[n]= k=04a kej2 kn5, where a…
  22. GATE 2023 EC Q48 (2 marks, Multiple choice) – Let an input x[n] having discrete time Fourier transform X(ej)=1-e-j+2e-3j be passed through an LTI system. The frequency response of the LTI system…
  23. GATE 2024 EC Q56 (2 marks, Multiple select) – The radian frequency value(s) for which the discrete time sinusoidal signal x[n]=A( n+/3) has a period of 40 is/are .
  24. GATE 2024 EC Q59 (2 marks, Numerical answer) – The relationship between any N-length sequence x[n] and its corresponding N-point discrete Fourier transform X[k] is defined as X[k]= F\x[n]\. Another…
  25. GATE 2025 EC Q27 (1 mark, Multiple select) – Let x[n] be a discrete-time signal whose z-transform is X(z). Which of the following statements is/are TRUE?