# EE 311 Name_________________ Hour Exam 2 March 6, 2015 ```EE 311
Hour Exam 2
Name_________________
March 6, 2015
1. Suppose the A/D converter is set up to do a 12-bit conversion on a signal that varies from 0 to
3 volts. I attached sensor to the port but the sensor only produces a signal that uses half of the
voltage range – say from 1 volt to 2.5 volts. How many volts does one-bit represent?
2. I have a sinusoid at 800 Hz which is sampled at 4 KHz. If I down sample by a factor of 4 to 1
KHz, what frequencies will be present in the range 0 to 500 Hz?
3. Write the transfer function for a 10th order moving average filter with a sample frequency of
44100Hz.
4. The step response for a linear DSP system is given below. What is the phase shift at fs/2?
Step response = {1, 3, 4, 4, 4, 4. . .}
5. For a given transfer function, if you double the sample frequency do the poles and zeros move
closer together, farther apart, or neither. Explain.
6. If you build a linear phase FIR filter for an audio system but you neglect to put on an antialiasing filter, how would you expect the output to differ from a similar system which did have
an antialiasing filter on it?
7. The two phase curves shown below are taken from a Matlab plot of two FIR filters which
have identical magnitude plots. What can you say about the relative positions of the zeros of the
two plots. The x axis is frequency in Hertz and the y axis is the phase angle in degrees.
100
50
0
-50
0
0.5
1
1.5
2
2.5
4
x 10
0
-100
-200
-300
-400
0
0.5
1
1.5
2
2.5
4
x 10
8. Circle the characteristics that apply for each of the following.
A)
B)
C)
9. Draw a pole/zero plot for a causal, stable, high pass FIR filter with a linear phase, a phase shift
of 90o at 0Hz, and a gain of 0 at fs/4. Minimize the number of poles and zeros to meet the
requirements.
10. If a step response is given by s(n) = {0.5, 0.75, 1.0, 1.5, 1.75, 1.0, 1.0, …} answer the
following questions:
A) What is the impulse response?