1. (TCO 1) A signal that is a function of time has the following properties (or the following applies to it). (Points : 4)

       It may originate from an electrical or a nonelectrical system (e.g., mechanical).
       
It cannot be periodic.
       
It must always be periodic.
       
It must always be discrete and never analog or continuous.

 

Question 2.2. (TCO 1) A sinusoidal signal, 20 sin(ωt + π/2 ), passing through an LTI system, undergoes a gain of 2 and a 90-degree phase lag. The resulting output signal will be mathematically described as (Points : 4)

       22 sin(ωt + π/2).
       
40 sin(ωt ).
       
10 sin(ωt + π/2).
       
40 sin(ωt – π/2).

 

Question 3.3. (TCO 1) Determine which of the following is a linear system by applying the principle of superposition.(Points : 4)

       y = 0.5 x +0.5
       
y = 0.5 x -0.5
       
y = .5 x
       
y = 0.5 x2 

 

Question 4.4. (TCO 1) A continuous time system has an output, y, which is a function of time and is given by . It is sampled at a frequency of 1 Hz. Determine the expression that correctly represents the discrete signal obtained after sampling and its value for n = 3. (Points : 4)

       y(n) = 3 n3 , value at n = 3 is 81.
       
y(n) = 5 n3 , value at n = 3 is 135
       
y(n) = 6 n2 , value at n = 3 is 54
       
y(n) = n3 , value at n = 3 is 27

 

Question 5.5. (TCO 1) A signal given by 5 Cos (20*pi*t) + 20 Sin (40*pi*t) is sampled at a rate of 50 Hz. Is the Nyquist theorem violated? (Points : 4)

       No, it is not violated.
       
Yes, it is violated.
       
Insufficient data to answer the question
       
Question cannot be answered because sampling time is unknown 

 

Question 6.6. (TCO 1) A sawtooth wave repeats itself every 0.05 seconds. The first three harmonics in this sawtooth wave have a frequency of (Points : 4)

       0.05, 0.1, 0.15 Hz.
       
40, 80, 120 Hz.
       
20, 40, 60 Hz.
       
50, 100, 150 Hz.

 

Question 7.7. (TCO 1) A discrete time sequence is shown below in a figure. All values not shown can be assumed to be zero. Describe the sequence as a sum of undelayed (if any) and delayed step functions.
 (Points : 3)

       - 2δ(n-1) - 2 δ(n-2) + δ (n-3) +δ (n-4)
       
δ(n-1) - 2 δ(n-2) - 2 δ (n-3) - δ (n-4)
       
-2δ(n) -  δ(n-1) -  δ (n-2) +  + δ(n-3)
       
δ(n-1) + 2 δ(n-2) + δ(n-3) +2 δ (n-4) 

 

Question 8.8. (TCO 1) A discrete time sequence is shown below in a figure. All values not shown can be assumed to be zero. Describe the sequence as a sum of undelayed (if any) and delayed step functions.
 (Points : 3)

       2U(n) -3 U(n-1)
       
2U(n-1) - 3U(n-2)
       
2U(n-1) -3 U(n-2) + U(n-3)
       
2U(n) +3 U(n-1) - U(n-3)

 



    • 9 years ago