Gibilisco - Wireless Transmitters And Receivers
- 1.
A radio wave has a frequency of 1.55 MHz. The highest modulating frequency that can beused effectively is about
- A.
1.55 kHz.
- B.
15.5 kHz.
- C.
155 kHz.
- D.
1.55 MHz.
Correct Answer
C. 155 kHz. -
- 2.
The reflected wave
- A.
Arrives in phase with the direct wave.
- B.
Arrives out of phase with the direct wave.
- C.
Arrives in a variable phase compared with the direct wave.
- D.
Is always horizontally polarized.
Correct Answer
C. Arrives in a variable phase compared with the direct wave. -
- 3.
An advantage of FSK over on/off keying is the fact that FSK
- A.
Offers better frequency stability.
- B.
Can provide faster data rates.
- C.
Reduces the number of receiving errors.
- D.
Forget it! On-off keying is just as good as FSK.
Correct Answer
C. Reduces the number of receiving errors. -
- 4.
The highest layer of the ionosphere is
- A.
The D layer.
- B.
The E layer.
- C.
The F layer.
- D.
None of the above.
Correct Answer
C. The F layer. -
- 5.
If an AM signal is modulated with audio having frequencies up to 5 kHz, then what is thecomplete signal bandwidth?
- A.
10 kHz
- B.
20 kHz
- C.
50 kHz
- D.
500 kHz
Correct Answer
A. 10 kHz -
- 6.
An LSB, suppressed-carrier signal can be demodulated by
- A.
An envelope detector.
- B.
A diode.
- C.
A ratio detector.
- D.
A product detector.
Correct Answer
D. A product detector. -
- 7.
Which of the following modes is used to send image data over telephone lines?
- A.
On/off keying
- B.
Fax
- C.
AM
- D.
Product detection
Correct Answer
B. Fax -
- 8.
The S/N ratio is a measure of
- A.
The sensitivity of a receiver.
- B.
The selectivity of a receiver.
- C.
The dynamic range of a receiver.
- D.
The efficiency of a transmitter.
Correct Answer
A. The sensitivity of a receiver. -
- 9.
Suppose an SSB suppressed carrier is at 14.335 MHz, and audio data is contained in a bandfrom 14.335 to 14.338 MHz. What is this mode?
- A.
DSB
- B.
LSB
- C.
USB
- D.
AFSK
Correct Answer
C. USB -
- 10.
A receiver that responds to a desired signal, but not to another signal very close by infrequency, has good
- A.
Sensitivity.
- B.
Noise figure.
- C.
Dynamic range.
- D.
Selectivity.
Correct Answer
D. Selectivity. -
- 11.
Fill in the blank in the following sentence to make it true: “The deviation of a narrowbandvoice FM signal normally extends up to either side of the unmodulated-carrier frequency.”
- A.
3 kHz
- B.
5 kHz
- C.
10 kHz
- D.
3 MHz
Correct Answer
B. 5 kHz -
- 12.
An FM detector with built-in limiting is
- A.
A ratio detector.
- B.
A discriminator.
- C.
An envelope detector.
- D.
A product detector.
Correct Answer
A. A ratio detector. -
- 13.
In which mode of PM does the peak power level of the pulses vary?
- A.
PAM
- B.
PDM
- C.
PIM
- D.
PFM
Correct Answer
A. PAM -
- 14.
A continuously variable signal (such as music audio) can be recovered from a signal havingonly a few discrete levels or states by means of
- A.
A ratio detector.
- B.
A D/A converter.
- C.
A product detector.
- D.
An envelope detector.
Correct Answer
B. A D/A converter. -
- 15.
In which mode are signals intertwined in the time domain at the transmitter, and thenseparated again at the receiver?
- A.
FDM
- B.
AFSK
- C.
PCM
- D.
None of the above
Correct Answer
D. None of the above -
- 16.
Which of the following modes can be demodulated with an envelope detector?
- A.
AM
- B.
CW
- C.
FSK
- D.
USB
Correct Answer
A. AM -
- 17.
The bandwidth of a fax signal is kept narrow by
- A.
Sending the data at a slow rate of speed.
- B.
Maximizing the number of digital states.
- C.
Optimizing the range of colors sent.
- D.
Using pulse modulation.
Correct Answer
A. Sending the data at a slow rate of speed. -
- 18.
The dynamic range in a superhet is largely influenced by the performance of the
- A.
Local oscillator.
- B.
Product detector.
- C.
Front end.
- D.
Selectivity in the IF chain.
Correct Answer
C. Front end. -
- 19.
Frequency sweeping can be used to get a transmitter to produce
- A.
Spread-spectrum signals.
- B.
Time division multiplexed signals.
- C.
Narrowband AM signals.
- D.
Double sideband, suppressed carrier signals.
Correct Answer
A. Spread-spectrum signals. -
- 20.
Fill in the blank to make the following sentence true: “The reception of can beimproved by the use of DSP.”
- A.
SSB signals
- B.
SSTV signals
- C.
Synchronized communications signals
- D.
Any of the above
Correct Answer
D. Any of the above -
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Current Version
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Mar 21, 2022Quiz Edited by
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Dec 09, 2010Quiz Created by
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