How the Mid-Term Exam was Marked

Question 1

• 4 marks for each of signal (-3 dB) and aliasing (-38 dB) powers.
• 2 marks for computing ratio in dB.

Question 2

• 4 marks for finding signal power -3 dB at 2 kHz
• 4 marks for finding aliasing power -38 dB at 2 kHz
• 2 marks for computing the ratio

Question 3

• (a): 5 marks: -1 mark per mistake
• (b): 4 marks: -1 mark per mistake
• (c): 6 marks:
  • 4 marks for the values
  • 2 for the plot
• (d): 3 marks:
  • 1 for peak
  • 2 for the nulls
• (e): 2 marks:
  • 1 for a `yes' answer
  • 1 for the reason

Question 4

• 3 marks for method: -1 mark per mistake
• 2 marks for finding numerical answer: -1 mark per mistake

Question 5

• 2 marks for correct amplitude/phase from 0 to N/4
• 2 marks for correct amplitude/phase from N/4 to N/2
• 2 marks for correct amplitude/phase symmetry from N/2 to 3N/4
• 2 marks for correct amplitude/phase symmetry from 3N/4 to N
• 1 mark for right amplitude values
• 1 mark for right phase values

Other Comments

• use 20log() if it's a voltage ratio
• use 10log() if it's a power ratio

You should be able to compute numerical answers using real-world numbers. Please bring a scientific calculator to the exam.