Midterm Q1b: Signal Transformation Solutions

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stanigator
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In question 1b of the midterm in the pdf attached below, I don't understand why the solution should be what it stated in the other pdf attached rather than what I did in the picture, which basically flips 1a along y-axis.
 
Attachments
  • Handwritten midterm solution sheet, rotated sideways: part 1a plots h(t+2) as a rectangular pulse with values 2 between t=-5 and t=-3 region and 2 at t=0 to t=2 on a time axis; part 1b shows h(-t-2) = h(-(t+2)) with a hand-drawn sketch of a pulse with amplitude 2 over roughly 0 to 3 and 3 to 5 on a time axis.
    CIMG0221.jpg
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  • mid1.pdf
    mid1.pdf
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  • mid1_solB.pdf
    mid1_solB.pdf
    271.4 KB · Views: 270
Flipping about the axis does not apply to the shift.
You have h(t), and you want to compute h(y(t)) where y(t) = -t-2.
h(-y(t)) [tex]\neq[/tex] h(y(-t))
The former is what you did, which is to compute y(t+2) and then flip, but that gives you y(-t+2), so then you need to shift by 4 to get y(-t-2).