Prepare the answers of the following questions.

Questions for Problem 1

1.1 For which of the signals is the real part of the FFT zero?
 a) x₁[n]
 b) x₂[n]
 c) x₃[n]
 d) x₄[n]

1.2 For which of the signals is the imaginary part of the FFT zero?
 a) x₁[n]
 b) x₂[n]
 c) x₃[n]
 d) x₄[n]

Questions for Problem 2

2.1 Why is the peak of the magnitude of the FFT greater for one of the sinusoids?
 a) The peaks of the two are actually exactly the same.
 b) The frequency of one of the sinusoids is closer to the nearest DFT frequency bin than the other.

2.2 When is the peak in the frequency domain higher?
 a) When the window length is 64.
 b) When the window lenght is 128.

Questions for Problem 3

3.1 What is the maximum value of N at which further increasing N does not provide any new information about the shape of the DTFT?
 a) N=8.
 b) N=16.
 c) N=32.
 d) N=64.

3.2 The triangular signal can be recovered from its 8 point FFT?
 a) True
 b) False

Questions for Problem 4

4.1 Which window is able to resolve better the 2 sinusoids?
 a) Rectangular
 b) Hamming

4.2 Why is the window mentioned in the previous problem able to resolve the two sinusoids?
 a) It has smaller side lobes.
 b) It has a narrower main lobe.

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