ET263 Practice Test I

Instructions: There are 25 questions on this test. It is written in a style very similar to the REAL exam #1. Choose the best answer from among those given. Click the GRADE button on the bottom of the form when you want the exam graded.

Note: You can practice this test as many times as you desire; the system will cook you up a fresh batch of questions each time you access this page.

Your Name: @ 3.230.154.90

1. What is the wavelength of a 600 MHz signal?

a) 1 Meter
b) 0.5 Meter (50 cm)
c) 0.75 Meter
d) None of the above

2. What type of filter is used to separate radio stations in a receiver?

a) Bandpass
b) Highpass
c) Lowpass
d) None of the above

3. Which of these describes the process of modulation?

a) Recovering information from a carrier wave
b) Placing information onto a carrier wave
c) Controlling the frequency of a carrier wave
d) None of the above

4. Why is modulation and carrier transmission necessary in radio?

a) To keep antenna lengths reasonable
b) To allow stations to be separated by radio receivers
c) Both A and B
d) None of these

5. Which of these describes demodulation?

a) Recovering information from a carrier wave
b) Placing information onto a carrier wave
c) Controlling the frequency of a carrier wave
d) None of the above

6. In troubleshooting a stage in an electronic device, where is the best place to check the power supply?

a) At the output terminal of the voltage regulator IC
b) Directly at the terminals of the device using the power
c) At the power supply buss line
d) None of the above

7. Why can't audio frequencies be directly transmitted through an antenna system?

a) The antenna required would be too long
b) Too much power would be required
c) The receiver would distort the information waveform
d) None of the above

8. What are the steps of troubleshooting in correct order?

a) Visual inspection, Check power supply, Check inputs & outputs
b) Check power supply, Visual inspection, Check inputs & outputs
c) Visual inspection, Check inputs & outputs, Check power supply
d) None of the above

9. The signal shown above is fed into a bandpass filter with a center frequency of 2 KHz. What will the output of the bandpass filter look like on an oscilloscope?

a) A 1 KHz square wave
b) A 1 KHz sine wave
c) A 2 KHz triangle wave
d) None of the above

10. What is the relationship of the 2 KHz frequency component to the 1 KHz component in the figure above?

a) The 2 KHz signal is twice the amplitude of the 1 KHz signal
b) The 2 KHz is a distorted form of the 1 KHz signal
c) The 2 KHz signal is the 2nd harmonic of the 1 KHz signal
d) None of the above

11. What type of wave is pictured in the spectrogram above?

a) Pure sine wave
b) Square wave
c) Triangle wave
d) None of the above

12. What frequency is two octaves above 1 KHz?

a) 2 KHz
b) 3 KHz
c) 5 KHz
d) None of the above

13. What noise voltage will be generated across a 100K resistor at room temperature (24 degrees Celsius) if the circuit's bandwidth is 1 MHz? (k=1.38 x 10-23 J/K)

a) 40.5 uV
b) 0.5 uV
c) 20 uV
d) None of the above

14. Which of these could be classified as an external noise source?

a) Shot Noise
b) Atmospheric noise
c) Flicker Noise
d) None of the above

15. What signal to noise ratio, in dB, will result if a system has 1 mW of noise and 100 mW of signal power?

a) 10 dB
b) 20 dB
c) 30 dB
d) None of the above

16. What type of noise is produced by devices with forward-biased PN junctions?

a) Cosmic noise
b) Johnson noise
c) Thermal noise
d) None of the above

17. An AM transmitter is operating on a carrier frequency (Fc) of 1500 KHz, with 50 volts of carrier (Vc). The transmitter is operating at 90% modulation. What is the intelligence voltage (Vm or Vi)?

a) 50 V
b) 40 V
c) 45 V
d) None of these

18. A certain AM transmitter produces 16W of power into a 50 Ohm load with no modulation. What total power will be produced at 50% modulation?

a) 17 W
b) 18 W
c) 20 W
d) None of the above

19. What is the percentage of modulation of the AM signal pictured above?

a) 20%
b) 10%
c) 30%
d) None of the above

20. What bandwidth will be required to transmit a 2 KHz sine-wave tone on an AM carrier wave if the carrier frequency is 118 MHz?

a) 10 KHz
b) 4 KHz
c) 8 KHz
d) None of these

21. New frequencies that are generated during the process of modulation are known as:

a) Harmonics
b) Fundamentals
c) Sidebands
d) None of the above

22. An AM signal was measured on an oscilloscope. The readings were Vmax=400 V, and Vmin = 100V. What is the percent modulation?

a) 33.3%
b) 60 %
c) 75 %
d) None of the above

23. An AM signal was measured on an oscilloscope. The readings were Vmax=300 V, and Vmin = 150V. What is the percent modulation?

a) 33.3 %
b) 50 %
c) 75 %
d) None of the above

24. Which of these is a consequence of overmodulating an AM transmitter?

a) Distortion of the information
b) Splatter (Excessive bandwidth)
c) Both A and B
d) None of the above

25. What is the frequency of the upper sideband for an AM transmitter with a carrier frequency of 710 KHz and an information frequency of 5 KHz?

a) 710 KHz
b) 711 KHz
c) 712 KHz
d) None of the above


Press GRADE EXAM button to see how you did!

Grade Exam!