Digital Signal Processing Mid - I, September - 2014

1.An LTI Discrete time system is causal if and only if
  • h(n)≠0 for n<0
  • h(n)=0 for n<0
  • h(n)≠ for n<0
  • h(n)≠0 for n>0
Answer: B
2.For Energy signals, the energy will be finite and the average power will be _______
  • Infinite
  • finite
  • zero
  • can not be defined
Answer: C
3.Identify the dynamic system
  • y(n) = ax2(n)
  • y(n) = ax(n)
  • y(n) = ax2(n) + x(n)
  • y(n) = x(n)+x(n-1)
Answer: C
4.Linear convolution of two sequences N1 and N2 produces an output sequence of length
  • N1 – N2 +1
  • N1 + N2 –1
  • N1 + N2 +1
  • 2N1 – N2 +1
Answer: B
5.In N-Point DFT of L point Sequence, the value of N to avoid aliasing in frequency spectrum is
  • N≠L
  • N≤L
  • N≥L
  • N=L
Answer: C
6.In an N-point sequence, if N=16 the total number of complex additions and multiplications using Radix-2 FFT are
  • 64 & 80
  • 80 & 64
  • 24 & 12
  • 64 & 32
Answer: D
7.The complex valued phase factor/twiddle factor, WN can be represented as
  • e-j2πN
  • e-j2π/N
  • e-j2π
  • e-j2πNK
Answer: B
8.The Z-Transform is a
  • Finite series
  • Infinite power series
  • Geometric series
  • Both a & c
Answer: B
9.The ROC of the signal x(n) = an for -5 < n < 5 is
  • Entire Z-plane
  • Entire z-Plane expect Z = 0 and Z = 
  • Entire Z-plane expect z = 0
  • Entire Z-plane expect z = 
Answer: B
10.Find the convolutions of the two signals x(n) = { 3, 2,1, 2} h(n) = {1, 2, 1, 2} is
  • y(n)={3,8,8,12,9,4,4}
  • y(n)={3,8,8,12,4,4,2}
  • y(n)={3,8,12,9,4,4}
  • y(n)={3,8,8,1,1,4,4}
Answer: A
11.A system is set to be _______________if the output doesn’t depends on future inputs and output.
Answer: Static (or) memory less
12.Appending zeros to a sequence in order to increase its length is called ______________
Answer: Zero padding
13.In _______________ method the overlapped samples in one of the output sequences are discarded.
Answer: Overlap save
14.If DFT of x(n) is X(K) then DFT ( Img x(n) ) is _______________
Answer: ½[x(K)-x*(N-K)]
15.The N-point IDFT of X(K) is x(n) is equal to _______________
Answer:
16.The Twiddle factor WN K is given by __________________
Answer: e-j2π/N
17.The _______________ of X(Z) is the set of all values of Z, for which X(Z) attains final value.
Answer: ROC
18.The Z-Transform and ROC of an u(n) is ______________ and ______________
Answer: Z/Z-a, łZł > łał
19.The ___________________ signals are represented by DFS.
Answer: Sine
20.The digital signal processing involves ______________ signals and ____________ systems.
Answer: Digital (or) discrete, Discrete time