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1. 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

2. What difference between radio stations allows receivers to separate them?

a) Each has a different amplitude
b) Each has a different phase
c) Each has a different frequency
d) None of the above

3. 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

4. A certain transmitter's antenna is 1/4 wavelength long and measures 29.528 inches. What is the actual operating frequency of this transmitter? (1 inch = 2.54 cm).

a) 25 MHz
b) 50 MHz
c) 100 MHz
d) None of the above

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. What is the wavelength of a 1 MHz signal?

a) 100 Meters
b) 200 Meters
c) 300 Meters
d) None of the above

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

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

8. 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

9. 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

10. What is the only "pure" waveform containing no harmonic energies?

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

11. 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

12. What is the frequency of the 3rd harmonic for the signal above?

a) 1 KHz
b) 2 KHz
c) 3 KHz
d) None of these

13. Which of these measures would decrease shot noise?

a) Decrease the forward DC bias current
b) Increase the junction voltage drop
c) Increase the forward DC bias current
d) None of the above

14. Which type of noise is caused by the thermal agitation of charge carriers within a conductor?

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

15. What noise voltage will be generated across a 47K resistor at room temperature (24 degrees Celsius) if the circuit's bandwidth is 500 KHz? (k=1.38 x 10-23 J/K)

a) 40.5 uV
b) 19.6 uV
c) 20 uV
d) None of the above

16. Noise can best be defined as:

a) Any undesired signal within a system
b) Pulses appearing at the output of a system
c) Distortion at the output of a system
d) None of the above

17. What is the information frequency in the AM signal pictured above?

a) 1 KHz
b) 2 KHz
c) 4 KHz
d) 5 KHz

18. 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

19. 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

20. 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

21. If the load resistance RL is 50 Ohms, what is the total power of the AM signal above?

a) 200 Watts
b) 204 Watts
c) 250 Watts
d) None of the above

22. What is the total bandwidth of the AM signal pictured above?

a) 500 Hz
b) 1 KHz
c) 2 KHz
d) 4 KHz

23. A certain AM transmitter produces 10W of power into a 50 Ohm load with no modulation. What total power will be produced at 100% modulation?

a) 15 W
b) 20 W
c) 30 W
d) None of the above

24. 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

25. An AM transmitter is operating on a carrier frequency (Fc) of 10.000 MHz, with 5000 volts of carrier (Vc). The transmitter is operating at 70% modulation. What is the voltage in the upper side band?

a) 3500 V
b) 2750 V
c) 2000 V
d) 1750 V

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