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TitleFrenzel Q & A
Tags Antenna (Radio) Frequency Modulation Modulation Detector (Radio)
File Size214.5 KB
Total Pages23
Document Text Contents
Page 1

Chapter 1: Introduction to Elec Comm

1. Communication is the process of
Ans: exchanging information

2. Two key barriers to human
communication are

Ans: distance and language

3. Electronic communications was
discovered in which century?

Ans: 19th

4. Which of the following is not a major
communications medium?

Ans: Water

5. Random interference to transmitted
signals is called

Ans: noise

6. The communications medium causes
the signal to be

Ans: attenuated

7. Which of the following is not a source
of noise?

Ans: Another communications signal

8. One-way communications is called
Ans: simplex

9. Simultaneous two-way
communications is called

Ans: Full duplex

10. The original electrical information
signal to be transmitted is called the

Ans: Baseband signal

11. The process of modifying a high
frequency carrier with the information to
be transmitted is called

Ans: modulation

12. The process of transmitting two or
more information signals simultaneously
over the same channel is called

Ans: Multiplexing

13. Continuous voice or video signals
are referred to as being

Ans: Baseband

14. Recovering information from a
carrier is known as

Ans: Detection

15. Transmission of graphical
information over the telephone network
is accomplished by

Ans: facsimile

16. Measuring physical conditions at
some remote location and transmitting
this data for analysis is the process of

Ans: Telemetry

17. Receiving electromagnetic
emissions from stars is called

Ans: Radio-astronomy

18. A personal communications hobby
for individuals is

Ans: ham radio

19. Radar is based upon
Ans: reflected radio signals

20. A frequency of 27MHz has a
wavelength of approximately

Ans: 11m

21. Radio signals are made up of
Ans: Electric and magnetic fields

22. The voice frequency range is
Ans: 300 to 3000 Hz

23. Another name for signals in the HF
range is

Ans: shortwaves

24. Television broadcasting occurs in
which ranges?

Ans: VHF

25. Electromagnetic waves produced
primarily by heat are called

Ans: infrared rays

26. A micron is
Ans: One-millionth of a meter

27. The frequency range of infrared rays
is approximately

Ans: 0.7 to 100μm

28. The approximately wavelength of
red light is

Ans: 7000 Ǻ

29. Which of the following is not used for

Ans: X-rays


Page 11

41. In a receiver with noise-derived
squelch, the presence of an audio signal
causes the audio amplifier to be

Ans: enabled

Chapter 8: Multiplexing

1. Multiplexing is the process of
Ans: sending multiple signals
simultaneously over a single channel

2. In FDM, multiple signals
Ans: share a common bandwidth

3. Each signal in a an FDM system
Ans: modulates a subcarrier

4. Frequency modulation in FDM
systems is usually accomplished with a

Ans: VCO

5. Which of the following is not a
typical FDM application

Ans: secure communications

6. The circuit the performs
demultiplexing in an FDM system is a(n)

Ans: Bandpass filter

7. Most FDM telemetry systems use
Ans: FM

8. The best frequency demodulator is

Ans: PLL discriminator

9. The modulation used in FDM
telephone systems is

Ans: SSB

10. The FDM telephone systems
accommodate many channels by

Ans: using multiple levels of

11. In FM stereo broadcasting, the L +
R signal

Ans: modulates the FM carrier

12. In FM stereo broadcasting, the L –
R signal

Ans: DSB modulates a subcarrier

13. The SCA signal if used in FM
broadcasting is transmitted via

Ans: A 67 kHz subcarrier

14. In TDM, multiple signals
Ans: take turns transmitting

15. In TDM, each signal may use he
full bandwidth of the channel

Ans: True

16. Sampling an analog signal

Ans: PAM

17. The maximum bandwidth that an
analog signal use with a sampling
frequency of 108 kHz is

Ans: 54 kHz

fn = fb / 2 = 108 kHz / 2 = 54 kHz

18. Pulse-amplitude modulation signals
are multiplexed by using

Ans: FET switches

19. In PAM demultiplexing, the receiver
clock is derived from

Ans: The PAM signal itself

20. In PAM/TDM system, keeping the
multiplexer and DEMUX channels step
with one another is done by a

Ans: Sync pulse

21. Transmitting data as serial binary
words is called

Ans: PCM

22. Converting analog signals to digital
is done by sampling and

Ans: Quantizing

23. A quantizer is a(n)
Ans: A/D converter

24. Emphasizing low-level signals and
compressing higher-level signals is

Ans: Companding

25. Which of the following is not a
benefit of companding?

Ans: Minimizes signal bandwidth

26. A telephone system using TDM
and PCM is called

Ans: T-1


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