25.
Which of the following media has the lowest error rates and the highest transmission speeds?
a. Coaxial cable
b. unshielded twisted pair
c. shielded twisted pair
d. fiber optic cable
e. infrared
26.
Transmission speeds:
a. are the same among all media
b. are not a factor in selecting a media because all media have more than enough speed
to serve current communication demands
c. are a constant, 56Kbps, for all media types
d. differ widely among media
e. always have a direct correlation with security
27.
A coding scheme that uses 10 bits to represent each character is capable of representing
_________ different characters.
a. 256
b. 20
c. 200
d. 512
e. 1024
28.
____________ is one of the most commonly used coding schemes used in data transmission.
a. ASCII
b. ISDN
c. MAU
d. ATM
e. FDM
29.
The representation of the character A by the group of 8 bits, 01000001, is an example of:
a. digital coding
b. phase modulation
c. binary modulation
d. analog transmission
e. pitch variation
30.
When all bits of a character are transferred one after another, the bits are transferred in
___________ mode.
a. serial
b. frequency division
c. multiplexing
d. parallel
e. full complex
31.
Which of the following statements is correct?
a. Parallel transmission is most often used for sending data on a circuit that is made up
of one wire.
b. Parallel transmission is distinguished from serial transmission by the fact that the
transmitting device sends a single bit, then a second bit, and so on, until all the bits
are transmitted.
c. Parallel transmission is only used for analog data.
d. Serial transmission is slower than parallel transmission.
e. Parallel transmission is the same as serial transmission.
32.
___________ is not a type of digital signaling technique.
a. Non-return-to–zero signaling
b. Unipolar signaling
c. Manchester encoding
d. Return-to-zero signaling
e. Data rate signaling
33.
With which type of digital signaling does the signal always return to zero volts after each bit?
a. Non-return-to–zero signaling
b. Unipolar signaling
c. Return-to-zero signaling
d. Data rate signaling
e. Huffman encoding signal
34.
Which type of digital signaling would experience fewer errors because it has more distinct
signals?
a. unipolar
b. serial
c. bipolar
d. attenuation
e. Huffman encoding signal
35.
Which of the following is a characteristic of sound waves that can be modulated to convert
digital data into analog signals?
a. phase
b. attenuation
c. bipolar
d. bandwidth
e. codec
36.
The direction in which the sound wave begins is known as:
a. amplitude, which our ears detect as loudness
b. frequency, which our ears detect as pitch
c. phase
d. bandwidth
e. furlong
37.
The height of a sound wave is called its:
a. frequency
b. phase
c. amplitude
d. bandwidth
e. furlong
38.
_____________ is not a form of modulation used to transform digital data into analog
signals.
a. synchronous time division
b. amplitude shift keying
c. amplitude modulation
d. frequency modulation
e. phase modulation
39.
____________ refers to changing the shape of the sound wave in different ways to represent
a 1 or a 0.
a. digitizing.
b. sampling
c. modulation
d. demodulation
e. shaping
40.
With respect to converting digital data into analog signals, AM stands for:
a. Asynchronous Manchester
b. Analog Multimode
c. Amplitude Modulation
d. Anomaly Multiplexing
e. Analytical Mosaic
41.
In which type of modulation is a 1 distinguished from a 0 by shifting the direction in which
the wave begins?
a. bandwidth modulation
b. amplitude modulation
c. frequency modulation
d. phase modulation
e. codec modulation
42.
When sending four bits at a time using frequency modulation, the number of different
frequency levels that would be needed would be _______.
a. 24
b. 16
c. 2
d. 8
e. 4
43.
____________ is a modulation technique that combines two different amplitude
combinations with eight different phase combinations modulation to send four bits per
symbol.
a. quadrature amplitude modulation
b. time division multiplexing
c. synchronous digital line control
d. pulse code modulation
e. baseband signaling
44.
The _____________ of a circuit determines a circuit’s capacity.
a. frequency
b. bandwidth
c. phase
d. amplitude
e. loudness
45.
The typical range of human hearing is:
a. 0 to 4,000 Hz
b. 0 to 1,200 Hz
c. 20 to 14,000 Hz
d. 0 to 300 Hz
e. 0 to 56,000 Hz
46.
If the highest frequency of a circuit is 10KHZ and the lowest frequency is 900 Hz, the
bandwidth available for this circuit is :
a. 890 Hz
b. 8900 HZ
c. 9100 Hz
d. 9Khz
e. 890 KHz
47.
To get more “bandwidth” in a digital transmission, you must:
a. increase the range of frequencies available for a transmission
b. increase the loudness per transmission
c. decrease the bits per second transmission speed
d. increase the phase shifts per transmission
e. decrease the baud rate per transmission
48.
Which of the following statements is true?
a. the longer the distance of a telephone wire between sender and recipient, the lower
the bandwidth across that wire
b. the shorter the distance of a telephone wire between sender and recipient, the lower
the bandwidth across that wire
c. bandwidth is constant across any wire, therefore distance is not relevant to its
capacity
d. the longer the distance of a telephone wire between sender and recipient, the higher
the bandwidth across that wire
e. bandwidth is not a term that can be used when discussing telephone transmissions
49.
The acronym, Modem, stands for _________________.
a. multiplexing/demultiplexing
b. more/demote
c. Mode-M technique
d. modulator/demodulator
e. Mod emulation technique
50.
______ is a modem standard that uses Lempel-Ziv encoding to compress data.
a. V.22
b. V.44
c. V.32bis
d. V.34
e. RS 232
51.
Equipment used to transform analog voice signals to digital signals and digital signals to
analog signals.
a. voice converter
b. modem
c. codec
d. multiplexer
e. demodulator
52.
_____________ refers to the difference between the original analog data and the
approximation of that data using the techniques for translating from analog data to digital
signals.
a. quantizing error
b. handshaking phase
c. modulating frequency
d. POTS anomaly
e. amplitude Trellis effect
53.
When converting analog voice data to digital signals, Pulse Code Modulation typically
samples the incoming voice signal _______ times per second.
a. 8,000
b. 8
c. 18,000
d. 64
e. 256
54.
How many bits are required to sample an incoming signal 4000 times per second using 64
different amplitude levels?
a. 64
b. 32
c. 16
d. 8
e. 6
55.
If each sample uses 16 bits and the number of samples taken each second is 8000; then the
transmission speed on the circuit is?
a. 128 Kbps
b. 64 Kbps
c. 12800 bps
d. 96 Kbps
e. 32000 bps
56.
A(n) ___________ divides one high-speed communication circuit into several lower speed
circuits for the primary reason of saving communication line costs.
a. transponder
b. multiplexer
c. inverse multiplexer
d. codec
e. intelligent terminal
57.
____________ is used by IM and other applications that provide voice services over lower-
speed digital circuits.
a. pulse code modulation
b. adaptive differential pulse code modulation
c. Voice conversation
d. code modulation
e. phase modulation
58.
The type of multiplexer that divides the circuit horizontally into different light frequencies
that are transmitted simultaneously across many channels is a:
a. wavelength division multiplexer
b. time division multiplexer
c. statistical time division multiplexer
d. frequency division multiplexer
e. statistical frequency division multiplexer
59.
Frequency division multiplexing:
a. operates by statistically time slicing the signal
b. operates by dividing the signal into different frequencies
c. uses a codec that divides signals into different channels
d. operates by time slicing the signal
e. operates by light dividing the signal
60.
Time (non-statistical) division multiplexing differs from frequency division multiplexing
because it:
a. does not share a communication circuit
b. splits the communication circuit vertically (with time slots) instead of horizontally
c. increases the wavelength and phase angles of the baseband frequency used for
transmission
d. moves the baseband of a circuit by shifting it to a higher frequency
e. reduces baseband signal velocity more than frequency division multiplexing
61.
A _________ is an FDM device that splits the physical circuit into three logical circuits
(phone, upstream data, downstream data).
a. DSL modem
b. cable modem
c. wireless router
d. V.44 modem
e. Serial modem
62.
When you send an email from the US to Europe, it likely is transmitted from one continent to
another through one of the ______ that connect America and Europe.
a. submarine cables
b. satellites
c. telephone lines
d. boats
e. modems
63.
The room that contains the cable termination points and the distribution frames is referred to
as
a. telecommunications closet
b. equipment room
c. building entrance
d. backbone room
e. work area
Essay and Short Answer Questions
1. Define analog, and then describe the conversion from analog to digital using a four
step method (sampling, measuring, quantizing and coding), and present a detailed
diagram like the one which in the slides. What is quantizing error and how can it
be lessened in some situations? Draw a sketch of quantizing error in your model.
2. Describe the three types of data flows, and discuss why some are applicable in
some situations and vice versa.
3. Describe three types of guided media. Give an example, describe what it looks
like and how it works, and why it might be used in a scenario of a network.
4. Describe four types of radiated media. Give an example, describe what it looks
like and how it works, and why it might be used in a scenario of a network.
5. What is the term used to describe the placing of two or more signals on a single
circuit?
6. What is the purpose of multiplexing? How does it work? Multiplexing usually is
done in multiples of _______ ? Of the different types of multiplexing, what
distinguishes
a. Frequency division multiplexing (FDM)? (describe and draw a sketch of
this)
b. Time division multiplexing (TDM)? (describe and draw a sketch of this)
c. Statistical time division multiplexing (STDM)? (describe and draw a
sketch of this)
d. Wavelength division multiplexing (WDM)? (describe)
7. If you were buying a multiplexer, why would you choose either TDM or FDM?
8. Describe two ways in which Statistical Time Division Multiplexing (STDM)
differs from Time Division Multiplexing (TDM).
9. Compare and contrast Frequency Division Multiplexing (FDM) and Wavelength
Division Multiplexing (WDM).
10. Under what circumstances would you use a microwave circuit rather than a
satellite circuit?
11. Explain two reasons why the use of twisted pair cable is becoming more common
than the use of coax cable?
12. How does analog data differ from digital data?
13. Clearly explain the differences between analog data, analog transmission, digital
data, and digital transmission.
14. Define digital data. Explain why most networks are now digital. Why is digital
transmission superior to analog? Give five reasons.
15. What is coding? Briefly describe the two most important coding schemes.
16. How is data transmitted in parallel? What feature distinguishes serial mode from
parallel mode?
17. How does bipolar signaling differ from unipolar signaling? Why is Manchester
encoding more popular than either? What kind of signaling is used in Ethernet?
18. What are the three important characteristics of a sound wave?
19. Describe how data could be transmitted using amplitude modulation.
20. Describe how data could be transmitted using frequency modulation.
21. Describe how data could be transmitted using phase modulation.
22. Describe how data could be transmitted using a combination of modulation
techniques.
23. Is the bit rate the same as the symbol rate? Explain.
24. What is a modem? How does a modem send digital data on an analog network,
explaining the process step by step?
25. Describe two common modem standards.
26. Why is data compression so useful? Describe how it works.
27. What is the typical sampling network in telephony? Why is a higher sampling rate
more effective for sound quality?
28. What is the difference between multiplexing and modulation? Why are each
important?
29. Compare and contrast data rate (i.e., bits per second) and symbol rate (also called
baud rate) by giving two concrete, different examples.
30. Describe the six subsystems of TIA/EIA 568-B.